CA2029267C - Method and system for upstream occlusion detection - Google Patents
Method and system for upstream occlusion detectionInfo
- Publication number
- CA2029267C CA2029267C CA002029267A CA2029267A CA2029267C CA 2029267 C CA2029267 C CA 2029267C CA 002029267 A CA002029267 A CA 002029267A CA 2029267 A CA2029267 A CA 2029267A CA 2029267 C CA2029267 C CA 2029267C
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- CA
- Canada
- Prior art keywords
- pressure
- fluid
- pump
- threshold
- occlusion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
- A61M5/16854—Monitoring, detecting, signalling or eliminating infusion flow anomalies by monitoring line pressure
- A61M5/16859—Evaluation of pressure response, e.g. to an applied pulse
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
- A61M5/16831—Monitoring, detecting, signalling or eliminating infusion flow anomalies
- A61M2005/16863—Occlusion detection
- A61M2005/16872—Upstream occlusion sensors
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/14212—Pumping with an aspiration and an expulsion action
- A61M5/14228—Pumping with an aspiration and an expulsion action with linear peristaltic action, i.e. comprising at least three pressurising members or a helical member
Abstract
The method and system for detecting occlusion in a fluid line upstream of a pump concerns a fluid pump with a pump cycle in which the upstream pressure of the fluid line is communicated to the downstream portion of the fluid line. A pressure sensor located downstream of the pump is capable of measuring a relatively large negative-going pressure in the fluid line. A signal is generated to indicate occlusion based upon detection of negative-going pressure.
Description
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METHOD AND SYSTEM FOR UPSTRE~M OCCLUSION DETECTION
BACKGROUND OF THE INVENTION
Field of the Invention:
This invention relates generally to monitoring fluid flow, and more particularly relates to monitoring upstream occlusion in an intravenous fluid administration system utilizing an infusion pump.
Descri~tion of Related Art:
Fluid delivery syskems for infusing parenteral fluids are commonly used in hospitals, and typically include a bottle of parenteral fluid, an infusion pump, and an intravenous (IV) set including a tubing extending from the infusion pump to a cannula at the distal end of the tubing. Such infusion pumps provide a positive means for controlling the amount of fluid administered, and are an alternative to gravitational flow systems which are readily adapted to include a drip chamber for monitoring the amount of fluid administered, and occlusion situations in th~e system~ Detection of upstream occlusions has typically been accomplished in infusion systems utilizing peristaltic pumps through the use of an optoelectric drop detector combined with a drip chamber.
The~drop detector senses the occlusion by detecting the absence o~drops, which may be due to a clamped or kinked upstream tubing, as well as an empty IV fluid container.
There is a need in the medical industry for elimination of such drop detectors in connection with IV
infusion pump systems. An upstream occlusion can simply be detected by addition of an upstream pressure 30~;transducer, but this alternative adds considerable cost to both the instrument and the disposable portion of the IV administration set.
One solution~ to this problem has been to ; incorporate a~pressure transducer in the infusion pump itself.~ In one such devlce a pressure transducer is :: :: ~ ~ : ::
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' ' , ' 2 ~3 placed in the middle of the pumping area, allowing direct measurement of pressure in the tubing segment, which is indicative of the inlet pressure. However, it would be desirable to permit detection of upstream occlusion in an intravenous fluid administration system utilizing a peristaltic pump without requiring modifications to the disposable set or the pumping mechanism itself. The present invention addresses these needs.
SUMMARY OF THE INVENTION
The present invention provides a method and a system for detecting occlusion in a fluid line upstream Qf a pump adapted to cause fluid to flow from an upstream portion to a downstream portion of the fluid line, the pump having a cycle with a period during which fluid pressure is communicated from the upstream portion to the downstream portion of the fluid line. Fluid pressure is monitored in the fluid line downstream of the pump to detect the occurrence of a negative-going pressure transient, and a signal is generated indicating an occlusion when negative-going pressure transient is detected.
In a preferred embodiment, a plurality of samples of pressure measurements are taken, the difference between two downstream fluid pressure measurements which are a predetermined sampling interval apart within each measurement cycle is determined, the difference is compared with a difference thr~shold value, and the occlusion signal is generated when the difference exceeds this difference threshold va}ue. In another embodiment, a downstream fluid pressure parameter is based upon the power content of the pressure waveform over a predetermined range of frequencies. This parameter is compared with a power level threshold and the occlusion signal i5 generated when the parameter exceeds this power level threshold.
Artifacts may also be detected and their existence ~ ~3 r~ J ~ ~
used to inhibit the generation of false occlusion alarms.
Sampling of the downstream pressure is inltiated prior to the time of communication of the upstream pressure to the downstream pressure and if pressure below a predetermined threshold is measured, or if the pressure is changing in excess o~ a predetermined threshold, the generation of an occlusion alarm can be inhibited. In the case of severe artifacts causing gross pressure changes, a subsequent occlusion alarm may be considered to be unreliable and during that pump cycle it can be inhibiited.
Other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, illustrating by way of example the features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE la, lb, lc, ld and le illustrate sequential states of a peristaltic pump mechanism;
FIG. 2 illustrates a typical downstream pressure waveform indicating an upstream occlusion during the period of non-flow of a peristaltie pump;
FIG. 3 illustrates a downstream pressure waveform with a total upstream occlusion;
FIG.~ 4 illustrates another downstream pressure waveform similar to that of Fig. 3, with a total upstream occlusion;
FIG. 5 is a schematic diagram of an IV
administration set~and a system for detecting an upstream occlusion in accordance with the invention:
FIG. 6 illustrates a downstream pressure waveform showing an;artifact occurring in the detection window;
FIG. 7 is a flow chart showing pressure measurement steps of the preferred method embodiment of the invention;
;~ FIG. 8 illustrates strip chart recordings of a sequence of downstream pressure measurements during a series of pump duty cycles, with the upper chart ,' ..
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illustratlng down5tream pressure, and the lower strip chart marking the time period of the detection window;
and FIG. 9 is a schematic diagram of an IV
administration set with another embodiment of an upstream occlusion monitoring system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As is shown in the drawings for purposes of illustration, the invention is embodied in a method and a system for monitoring upstream occlusion in an IV
administration set based upon downstream pressure measurements. According to the currently preferred mode of the invention, a pressure measurement is taken at the beginning of a predefined detection window in a period of the pump cycle. Thereafter the downstream fluid pressure is sampled periodically for the rest of the detection period. With every new sample taken a test is performed for ;possible upstream occlusion. This test involves three values: the first sample taken at the beginning of the detection window, the present sample and the sample a given time period (10 ms) before the present sample. If the~ first pressure sample is above a given threshold (minus 120 mmHg) and the present pressure sample is below a given threshold (minus 30 mmHg) and the negative pressure difference between the present sample and the sample the given time period (10 ms) before the present sample exceeds another threshold (more than -60 mmHg) an occlusion has been detected. If the first pressure sample is below the threshold (minus 120 mmHg) 30 ~an artifact condition is detected and a possible occlusion~ cannot be detected during this particular period o~ cyclicaI transition in the flow cycle of the infusion pump. Thus, the method can also be used for preventing false alarms of upstream occlusion when an artifact such as would occur due to patient motion would otherwise indicate occlusion. ~n another embodiment of ~, ' I
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the invention, pressure measurements are taken continuously to determine the energy content during a predetermined period of the flow cycle of the pump, over a predetermined range of frequencies, to determine a downstream pressure parameter, and this parameter is compared with a threshold to identify upstream occlusion conditions. Since the pressure measurements can be taken downstream of the pump mechanism, the upstream occlusion monitoriny system can be installed conveniently and at a minimum of expense in existing IV administration sets in which a downstream pressure sensor is already present for measurement of infusion pressures.
Referring now to Figs. la-le, a peristaltic pump generally encloses a pumping segment 10 of a fluid line 12, which is manipulated by peristaltic fingers to force fluid through the line. The most upstream peristaltic finger 14 moves to fully occlude the fluid line in the pumping segment. This marks the beginning of a period of non~flow in the flow cycle of the pump. The most downstream finger 16 disengages, allowing communication of fluid .in the pumping segment between the most upstream finger 14 and the most downstream finger with the downstream portion of the fluid line. It has been observed that lf the IV set is clamped off upstream of the pump,~ a relatively large negative-going pressure ;~ transient 18 may be detected by a pressure sensor located downstream during the cyclical flow transition period when the downstream finger opens the pump tubing to the downstream portion of the IV tubing which is generally connected to a patient. This negative-going pressure transient is caused by the vacuum 19 that is generated in the tubing when the flow of fluid into the pumping section of the tubing is restricted. When this vacuum is suddenly connected to the downstream side of the tubing, a detectable transient occurs in the pressure in the downstream fluid line.
In Figures la - le, the pumping mechanism is .
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advancing fluid from the upstream portion of the line to the downstream portion of the line (left to right in the diagram). Upstream pressures are shown on the left of the pumping segment illustration, and downstream pressures are shown on the right side of the pumping segment illustrations. A total occluslon exists in the upstream line. In Figures la to ld an increasing partial vacuum is generated by the displacement of the pumping mechanism. When the vacuum generated during the states shown in Figures la - ld i5 suddenly connected to the pressure transducer located in the downstream tubing, the output signal of the pressure transducer drops very sharply as is shown in Fig. le. Since downstream fluid impedance is typically low, a small amount of fluid is drawn backward allowing the tubing walls downstream of the most upstream finger 14 to return to their original dimensions. This allows the pressure to rise again until it reaches static conditions. The rate of this equalization and the shape of this pressure transient depends on the downstream fluid impedance determined by the IV set, filters, cannula, and the patient. The pressure may overshoot if the recovery is fast enough, causin~ the mass of the fluid column to oscillate with the compliance of the tubing. The initial negative 2~ pressure-going transient 18 is shown in Fig. le, and the positive pressure transient 20 may help distinguish the negative-going pressure translent sufficiently so that an occlusion is readily identifiable.
A well known feature of a conventional peristaltic pump is its non-uniform flow rate over each cycle, with an actual non-flow period typically over 25 percent of the duty cycle of the pump. This cyclical flow transition period may be minimized in the pump by operating the stepper motor which drives the pump at its ~X;~ll~ rate during the transition phase. It is in this so-called 'Jspeed up" time period where the pinch-off point of the pumping fingers switches from downstream to ~i ~ 2 ~ '7 upstream, opening the pump tubing to the downstream portion of the IV tubing leading to the pressure transducer and the patient. The increase in speed of the motor is synchronized by a rotation sensor, such as a rotating dlsk which rotates in correlation with the rotation of the cam mechanism of the pump, and ~hich bears one or more detectable flags. This switching of pinch-off point from downstream to upstream thereby communicating the upstream pressure to the downstream pressure permits the definition of a detection "window"
where the negative-going transient will occur when there is occlusion upstream of the pump. This narrow window reduces susceptibility of the upstream occlusion detection system to artifact transients, which may, for example, be caused by movement of the IV tubing.
A typical pressure waveform 22 resulting from an upstream occlusion during a flow transition period is illustrated in Fig. 2. The pressure at the beginning cycle is about 20 mmHg at point 24. At point 26 the most downstream finger opens the pumping segment of the tubing to the downstream side and the pressure at the transducer drops sharply. This all occurs within the detection window 30 within the flow transition period 28. The pr ssure drops from the starting pressure 32 during the pressure transient 34 down to the bottom pressure 36.
Fluid begins to flow back during the recovery 38, filling the collapsed pumping segment of the tubing, resulting in the high pressure point or overshoot at 40, followed by the equalization of pressure at 42. A typical pressure ;30 waveform with a total upstream occlusion using a large, lower resistance, metal cannula terminating in a patient line is illustrated in Fig. ~. Superimposed on the chart is the si~nal from a rotation flag sensor 44. As in Fig.
2, the flow transitîon period 46 begins at the positive going edge of this signal, which coincldes with the flag of the rotation flag sensor no longer being detected by a photosensor associated with the rotation flag sensor.
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-, - . ' ' ~ : , :, ' ': , , ' ' . ' ' ' : ' When a neyative-aoing pressure transient 48 occurs during the detection window, the positive-going pressure overshoot transient 50 again follows, as before. Fig. 4 represents a similar pressure waveform for the same condition with a smaller diameter cannula. The rotation flag sensor timing 52 also marks the beginning of the flow transition period 54, during which the negative-going pressure transient 56 occurs, again followed by the recovery 58. In both Fig. 3 and Fig. 4 two negative-going pressure transients are shown. It is apparent thatthe pressure between the flow transition periods is somewhat positive in each case. The pressure falls sharply when the pump tubing opens to the pressure sensor. An important feature of this negative-going pressure transient is an extremely short fall time. The pressure change occurs in less than three sampling periods (15 msecs.) which helps to discriminate against artifact transients because other pressure translents do not change this quickly. Varlance in the duration of the negative transient between Fig. 3 and Fig. 4 is caused by the termination of the tubing with different cannula or needIe sizes. The lower resistance cannula allows fluid to flow back into the pump tubing much faster, enabling the pressure to equalize in a shorter time~
A typical system setup for occlusion sensing is illustrated in Fig. 5. A conventional intravenous fluid bottle 60 is connected with an IV spike and drip chamber 62 through the upstream IV tubing 64 and IV tubing clamp 66 to the peristaltic pump mechanism 68. The peristaltic pump includes the peristaltic pump mechanism and rotation sensor 70, associated with the peristaltic fingers 72, which press upon the fluid line pumping segment 74 placed adjacent the fingers to cause fluid to flow through the line. A convenient placement for the pressure sensor module 76 and the pressure transducer 78 is immediately downstream of the pumping mechanism, within the housing of the peristaltic pump.~ A pressure transducer with negative pressure sensing capability to about -200 mmHg (gauge) is preferred. The downstream tubing 30 includes a cannula or needle 82 at its distal end, suitable for placement in vein of a patient, or in a vein simulator 84, which was used for testing purposes. A rotation sensor signal line 86 carries the rotation sensor signal from the pump and rotation sensor mechanism to an analog to digital converter 90, which is also connected with the pressure signal line 88 to the pressure transducer to receive and digitize the pressure signal as a series of discrete digitized samples, for determination of a downstream pressure parameter by a signal processing unit 92.
The pump rate was found to have an effect on the vacuum ~eing generated with a partial upstream occlusion.
With any given fluid resistance upstream the vacuum will be essentially proportional to the pump rate. This means, that in cases of partial upstream occlusion, at low rates a higher upstream fluid resistance will be tolerated than at high pump rates before an occlusion is detected.
The termination resistance (R~ of the patient tu~ing affects the waveform of the speedup pressure transient. Tests were performed with large, low rasistance cannula (R = 14 m~Hg/liter/hr), a small cannula higher resistance (R = 550 mmHg/liter/hr), and a narrow lumen infusion catheter (R = 1000 mmHg/liter/hr).
The fall time and~ amplitude of the negative-going transient were practically unaffected by the terminating resistance. However, the recovery to the static pressure is strongly dependent on cannula size, and was found to take longer with a hlgher~flow resistance (Fig. 3 and 4).
: ~ The range of -2 to +10 psi (-100 to +500 mmHg) was considered a practical operating region for detectiny ~ 35 upstream occlusion conditions. The full range was tested ;~ ~ with large and small;needle sizes, both occluded and not occluded upstream. A static nPgative pressure of -100 :
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, mmHg takes into account that the pump may be located up to 4 feet above the IV site. The positive pressure is the maximum operating pressure of the pump without going into high pressure alarm.
~hile not intending to be bound by theory, it is believed that the pressure transient amplitude vs. the upstream minus downstream pressure difference appears to be a linear function of this pressure differsntial. Th~
transient amplitude is about 40~ of the pressure differential and is independent of needle size. With an occlusion that reduces the flow rate to 50~ of the selected rate the pressure transient amplitude is alm~st as high as with a total occlusion (zero flow rate). A
typical infusion pump drop rate detector design detects an upstream occlusion when the drop rate is 50% of the selected rate.
The volume of fluid between the pump and the occlusion will affect the amount of fluid that has to be pumped before the negati~e pressure transient will become large enough to be detected. The rate at which this negative pressure waveform builds up is also dependent on the volume and elasticity of the tubing between the pump and the occlusion. The larger and softer that the tubing is the more fluid will have to be pumped for a given negative pressure waveform.
The number of pump rotations necessary for the pressure transient to reach the full amplitude was measured using a standard Ivac infusion set with about 24 inches of vinyl tubing between the drip chamber and the pump. With the occlusion near the pump it takes about 1/2 rotation, and with the occlusion near the drip chamber it takes about two rotations for the pressure transient to become full size. The fact that it takes two rotations of the pump mechanism before the full amplitude appears does not mean that the whole amount of fluid is not being delivered to the patient (0.2 ml).
The pressure transient amplitude has been found to - , .
increase much faster than the pump rate drops off. As an example, when the pressure transient size has reached 50%
(110 mmHg) of the final transient slze (220 mmHg) the pu~p rate has only declined 15%. Fluid will still go to the patient while the vacuum is building up in spite of an upstream occlusion in the tubing.
Fig. 6 shows a time expanded view of an artifact which could produce a ~alse occlusion alarm such as might occur due to patient motion occurring in the detection window. By monitoring the pressure from the start of the non-flow period 110 to the start of the detection window 114, artifacts may be identified. The pressure is fairly constant during this artifact testing time period 112 if no artifacts are present. However, if the pressure should change noticeably, an artifact condition would be suspected and an occlusion alarm could be inhibited. If this condition should exist for more than one or two speedup cycles in a row an alarm indicating the artifact condition could be given. Thus, the pressure measurement between the start of the non-flow period and the start of the detection window can be stored as a threshold value, to determine if a subsequent pressure value in this interval is greater than or equaI to the suspected artifact pressure measurement~ However, in the tests that were performed, the tubing needed to be struck very hard in order to interfere with the detection of an actual transient or cause a false alarm. This would probably not occur under normal conditions such as ambulation of the patient.
One currently preferred method for detecting upstream occlusions involves monitoring the difference in the pressure between two samples which are two sample periods apart (10 ms), and by measuring the pressure level at the start of the detection window and at the bottom of the pressure transient. Decisions will be based on these three values~ The measurement of these values will only be performed during a short time period : ~ .
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defining the detection window in the flow transition period of each duty cycle, from approximately 50 to 100 ms after the start of the flow transition period. These times are specific to the stepping rate of the IVAC 560 pump during the non-flow transition time and they would have to be modified depending on the actual step rate of the motor but in terms of the rotation sensor timing 108, the detection window should always be at the same number of motor steps after the rotation flag of the rotation sensor is no longer detected by the photo sensor. The actual location and width of the detection window may need to be adjusted for each particular type of pump and rotation sensor 108.
Fig. ~ is a flow chart of the method, which was tested with recorded data. The operating range of the transducer was set to -200 to +500 mmHg. At the start 116 of the method, typically all values to be measured are initialized in a central processing unit, such as, for example, the Intel 85. During each cycle of the infusion pump, the start of the non-flow period 118 is determined based upon the tracking of the pump by the rotation sensor. When the start of the non-flow period is determined, a delay of 50ms. past the start of the non-flow period may be used for detecting occlusion artifacts. After 50 ms., the first pressure measurement is taken 122, and compared at 124 with a threshold of -120 mm Hg., for example. If the measured pressure is less than the threshold, the extraordinary reading is determined at 126 to be an artifact, indicating an occlusion can not be reliably detected even if it is present. Otherwise, this first pressure reading is stored in memory locations P0, P1, and P2 as is shown generally at 128. In another aspect of the method, a parameter of the stability of fluid pressure may be determined from pressure measurements taken from the start of the non-flow period during the 50ms. delay.
Such a parameter would be the root mean square of the pressure measurements during this delay interval, and if this root mean were to exceed a reference threshold value, an artifact condition would similarly be indicated.
During the first 50 milliseconds of the non-flow interval, the measured downstream pressure is not being influenced by the flow of fluid and has not yet reached the point at which the vacuum trapped between the upper and lower "fingers" is released. Therefore, this lo interval may be examined to determine if there is a large variation in pressure occurring due to vibration of the tubing or pressure variations caused by patient physiology (coughing, etc.) Such variations could reduce the effectiveness of the detectlon algorithm.
The pressure will be sampled a number (typically 10-20) of times depending on specifics of the mechanism.
From these samples a calculation of signal variability will be made and compared with a threshold. A typical means to determine the variability is the calculation of Root Mean Square power in the signaI. This RMS value is compared with a fixed threshold, and if the R~S value exceeds the threshold, then the measurement is not considered reliable and is not used for alarm purposes.
Determination of the standard deviation of the pressure samples in this pre-transient period may also be used.
Another method involves computing the sum of the absolute difference b~tween successive samples of pressure o~er the interval. This value increases with short term variability just as does the AC RMS or standard deviation calculations but does not require the use of multip~lication and therefore is more readily implemented in small microcomputers.
After the first sample is taken, at the beginning o~ the detection window, the system cycles at 130 to test whether the next sample period of 5ms. has passed. After 5ms., the value of Pl is stored in the memory of the CPU
as P2, the value of P0 is stored as Pl, and a new ''' ~ ' , , .-.: .
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pressure reading of P0 is taken. The difference between P2 and P0 is then compared at 134 with a difference threshold value of 60 mmHg, for example, and if the difference is greater than this 60 mmHg threshold, the value of P0 is compared ~ith a negative pressure th~eshold of -30 mmHg, for example, at 138 to determine whether there has been an occlusion 140. As an alternative, the slope of the pressure transient may be determined from one or more pairs o~ pressure samples, and compared with a slope threshold, to determine whether a sufficiently sharp negative-going transient has occurred to indicate upstream occlusion. The process of measuring and comparing the difference in pressure between two samples two sample periods apart can continue as long as the detection window, at lOOms, has not ended, at 136. After lOOms from the onset of the non-flow period, the detection window is closed, and the system cycles to test for the beginning of the next non-flow period at 118.
20Fig. 8 shows a strip chart recording of a pressure waveform 142 in the upper channel of a sequence of snapshots of the downstream~pressure during consecutive non-flow periods. The lower channel marks the detection window~ period (50 milliseconds). A negative-going 25~ marker ln this time period indicates that an occlusion ' was dete~ted. A positive-going mar~er at the beginning of the detec~ion window 14~ indicates that the transducer pressure was less than -120 mmHg at that moment making it impossible to detect a possible occlusion. This example shows the start of an occlusion 144. In the first non-flow period no translent appears. In the second, a small transi-nt starts showing, but is not large enough to trigger the detection. In the third non~flow period, the transient 148 has grown large enough to be detected. In the following periods No. 4 to 8, the transient is larger and larger and will be detected every time.
~ Another embod;iment of an upstream occlusion : : : : :
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, .. ~ . -detection system is illustrated in ~ig. 9. Thls system is similar in most respects to the system shown in Fig.
5, and accordingly, like or corresponding elements bear like reference numerals. The principal difference in this upstream occlusion detection system is that the pressure signal is transmitted through a delta modulator circuit 157 detecting pressure signals within a frequency band of 5 to 30 Hz. The delta modulator circuit typical y comprises a first low pass filter 151a, receiving the pressure signal via line 88, and functioning to prevent high frequency artifacts from corrupting the detection circuit function. The frequency characteristics of the low pass filter 151a are determined by the upper frequency boundary of the occlusion waveform spectrum, typically 20-30Hz. A second low pass filter 151b, receives the pressure signal via line 88, and operates to provide an output which is essentially a time weighted average of the incoming signal. A comparator 151c receives output from both the first and second low pass filters. The comparator is one having hysteresis which compares the outputs o~ the first and second low pass filters, switching when the difference of the signals changes polarity. Typically this output changes on the positive-going rebound portion of the large transient pressure signal found during a non-flow period when an upstream occlusion exists. The circuit is therefore sensitiv~ to changes in power in this frequency band, indicative of an upstream occlusion waveform occurrence.
The digital output latch 154 detects the rising edge of the output of the comparator, and transmits a digital error signal to be counted by a central processing unit 155, whi.ch in turn executes the reset 156 of the digital output latch 154. The output of the latch is sampled by the cenkral processing unit during the non flow ~ 35 transition period. This limits interfe~ence from noise ; ;and artifacts. The upstream occlusion appears as a sharp negatiYe-going pressure transient during the non flow . - :, -: . .
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transition period, followed by a positive rebound pressure signal. Spectral analysis, such as by Fourier analysis of the pressure waveforms, indicates a noticeable power content increase in frequencies from 5 to 30 Hz during occlusion.
The low pass filters 151a, 151b, the comparator 151c and the latch 154 of the delta modulator 157 thus discriminate power in this frequency band. 'rhe output of the circuit changes a digital level based upon whether the power in the band exceeds the power threshold level, set by the hysteresis of the comparator. The central processing unit includes a counter, which is toggled by the output latch on the transition from low to high count detection, and which will indicate an error when the count exceeds a given threshold value, in the display 158, which may be a chart or a computer monitor, for example. The frequency band can be widaned or narrowed, and a different frequency band for detection can be selected, such as from 40 - 50 Hz. Appropriate self-testing capalbility for calibration purposes may be added,for increased reliability of the system.
In another embodiment, the power in the frequency band of the pressure waveform may be determined by the central processing unit by determining the root mean ~square of the analog signal during the non-flow period, the sum of the sample pressure values minus a baseline or "starting" pressure, or otherwise determining an integral of the measured pressure values during the detection window, and displayed on a display unit 158.
Based upon the foregoing, it can be appreciated that~the method and system for detecting occlusion in a fluid line upstream~ ~of a peristaltic pump in an intravenous fluid administration system provides for a simplified, low cost, way of monitoring upstream occlusion without the necessity o~ modification of existing peristaltic pump~ mechanisms. Placed in a :: :
downstream conflguration, the system of the invention can ~ - .
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' j~J ~ 7 be readily adapted to monitor upstream occlusion in existing peristaltic pump IV infusion systems.
Although specific embodiments of the invention have been described and illustrated, it is clear that the invention is susceptible to numerous modifications and adaptations within the ability of those skilled in the art and without the exercise of the inventive faculty.
Thus, it should be understood that various changes in form, detail and uses of the present invention may be made without departing from the spirit and scope of the invention.
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METHOD AND SYSTEM FOR UPSTRE~M OCCLUSION DETECTION
BACKGROUND OF THE INVENTION
Field of the Invention:
This invention relates generally to monitoring fluid flow, and more particularly relates to monitoring upstream occlusion in an intravenous fluid administration system utilizing an infusion pump.
Descri~tion of Related Art:
Fluid delivery syskems for infusing parenteral fluids are commonly used in hospitals, and typically include a bottle of parenteral fluid, an infusion pump, and an intravenous (IV) set including a tubing extending from the infusion pump to a cannula at the distal end of the tubing. Such infusion pumps provide a positive means for controlling the amount of fluid administered, and are an alternative to gravitational flow systems which are readily adapted to include a drip chamber for monitoring the amount of fluid administered, and occlusion situations in th~e system~ Detection of upstream occlusions has typically been accomplished in infusion systems utilizing peristaltic pumps through the use of an optoelectric drop detector combined with a drip chamber.
The~drop detector senses the occlusion by detecting the absence o~drops, which may be due to a clamped or kinked upstream tubing, as well as an empty IV fluid container.
There is a need in the medical industry for elimination of such drop detectors in connection with IV
infusion pump systems. An upstream occlusion can simply be detected by addition of an upstream pressure 30~;transducer, but this alternative adds considerable cost to both the instrument and the disposable portion of the IV administration set.
One solution~ to this problem has been to ; incorporate a~pressure transducer in the infusion pump itself.~ In one such devlce a pressure transducer is :: :: ~ ~ : ::
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' ' , ' 2 ~3 placed in the middle of the pumping area, allowing direct measurement of pressure in the tubing segment, which is indicative of the inlet pressure. However, it would be desirable to permit detection of upstream occlusion in an intravenous fluid administration system utilizing a peristaltic pump without requiring modifications to the disposable set or the pumping mechanism itself. The present invention addresses these needs.
SUMMARY OF THE INVENTION
The present invention provides a method and a system for detecting occlusion in a fluid line upstream Qf a pump adapted to cause fluid to flow from an upstream portion to a downstream portion of the fluid line, the pump having a cycle with a period during which fluid pressure is communicated from the upstream portion to the downstream portion of the fluid line. Fluid pressure is monitored in the fluid line downstream of the pump to detect the occurrence of a negative-going pressure transient, and a signal is generated indicating an occlusion when negative-going pressure transient is detected.
In a preferred embodiment, a plurality of samples of pressure measurements are taken, the difference between two downstream fluid pressure measurements which are a predetermined sampling interval apart within each measurement cycle is determined, the difference is compared with a difference thr~shold value, and the occlusion signal is generated when the difference exceeds this difference threshold va}ue. In another embodiment, a downstream fluid pressure parameter is based upon the power content of the pressure waveform over a predetermined range of frequencies. This parameter is compared with a power level threshold and the occlusion signal i5 generated when the parameter exceeds this power level threshold.
Artifacts may also be detected and their existence ~ ~3 r~ J ~ ~
used to inhibit the generation of false occlusion alarms.
Sampling of the downstream pressure is inltiated prior to the time of communication of the upstream pressure to the downstream pressure and if pressure below a predetermined threshold is measured, or if the pressure is changing in excess o~ a predetermined threshold, the generation of an occlusion alarm can be inhibited. In the case of severe artifacts causing gross pressure changes, a subsequent occlusion alarm may be considered to be unreliable and during that pump cycle it can be inhibiited.
Other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, illustrating by way of example the features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE la, lb, lc, ld and le illustrate sequential states of a peristaltic pump mechanism;
FIG. 2 illustrates a typical downstream pressure waveform indicating an upstream occlusion during the period of non-flow of a peristaltie pump;
FIG. 3 illustrates a downstream pressure waveform with a total upstream occlusion;
FIG.~ 4 illustrates another downstream pressure waveform similar to that of Fig. 3, with a total upstream occlusion;
FIG. 5 is a schematic diagram of an IV
administration set~and a system for detecting an upstream occlusion in accordance with the invention:
FIG. 6 illustrates a downstream pressure waveform showing an;artifact occurring in the detection window;
FIG. 7 is a flow chart showing pressure measurement steps of the preferred method embodiment of the invention;
;~ FIG. 8 illustrates strip chart recordings of a sequence of downstream pressure measurements during a series of pump duty cycles, with the upper chart ,' ..
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illustratlng down5tream pressure, and the lower strip chart marking the time period of the detection window;
and FIG. 9 is a schematic diagram of an IV
administration set with another embodiment of an upstream occlusion monitoring system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As is shown in the drawings for purposes of illustration, the invention is embodied in a method and a system for monitoring upstream occlusion in an IV
administration set based upon downstream pressure measurements. According to the currently preferred mode of the invention, a pressure measurement is taken at the beginning of a predefined detection window in a period of the pump cycle. Thereafter the downstream fluid pressure is sampled periodically for the rest of the detection period. With every new sample taken a test is performed for ;possible upstream occlusion. This test involves three values: the first sample taken at the beginning of the detection window, the present sample and the sample a given time period (10 ms) before the present sample. If the~ first pressure sample is above a given threshold (minus 120 mmHg) and the present pressure sample is below a given threshold (minus 30 mmHg) and the negative pressure difference between the present sample and the sample the given time period (10 ms) before the present sample exceeds another threshold (more than -60 mmHg) an occlusion has been detected. If the first pressure sample is below the threshold (minus 120 mmHg) 30 ~an artifact condition is detected and a possible occlusion~ cannot be detected during this particular period o~ cyclicaI transition in the flow cycle of the infusion pump. Thus, the method can also be used for preventing false alarms of upstream occlusion when an artifact such as would occur due to patient motion would otherwise indicate occlusion. ~n another embodiment of ~, ' I
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the invention, pressure measurements are taken continuously to determine the energy content during a predetermined period of the flow cycle of the pump, over a predetermined range of frequencies, to determine a downstream pressure parameter, and this parameter is compared with a threshold to identify upstream occlusion conditions. Since the pressure measurements can be taken downstream of the pump mechanism, the upstream occlusion monitoriny system can be installed conveniently and at a minimum of expense in existing IV administration sets in which a downstream pressure sensor is already present for measurement of infusion pressures.
Referring now to Figs. la-le, a peristaltic pump generally encloses a pumping segment 10 of a fluid line 12, which is manipulated by peristaltic fingers to force fluid through the line. The most upstream peristaltic finger 14 moves to fully occlude the fluid line in the pumping segment. This marks the beginning of a period of non~flow in the flow cycle of the pump. The most downstream finger 16 disengages, allowing communication of fluid .in the pumping segment between the most upstream finger 14 and the most downstream finger with the downstream portion of the fluid line. It has been observed that lf the IV set is clamped off upstream of the pump,~ a relatively large negative-going pressure ;~ transient 18 may be detected by a pressure sensor located downstream during the cyclical flow transition period when the downstream finger opens the pump tubing to the downstream portion of the IV tubing which is generally connected to a patient. This negative-going pressure transient is caused by the vacuum 19 that is generated in the tubing when the flow of fluid into the pumping section of the tubing is restricted. When this vacuum is suddenly connected to the downstream side of the tubing, a detectable transient occurs in the pressure in the downstream fluid line.
In Figures la - le, the pumping mechanism is .
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advancing fluid from the upstream portion of the line to the downstream portion of the line (left to right in the diagram). Upstream pressures are shown on the left of the pumping segment illustration, and downstream pressures are shown on the right side of the pumping segment illustrations. A total occluslon exists in the upstream line. In Figures la to ld an increasing partial vacuum is generated by the displacement of the pumping mechanism. When the vacuum generated during the states shown in Figures la - ld i5 suddenly connected to the pressure transducer located in the downstream tubing, the output signal of the pressure transducer drops very sharply as is shown in Fig. le. Since downstream fluid impedance is typically low, a small amount of fluid is drawn backward allowing the tubing walls downstream of the most upstream finger 14 to return to their original dimensions. This allows the pressure to rise again until it reaches static conditions. The rate of this equalization and the shape of this pressure transient depends on the downstream fluid impedance determined by the IV set, filters, cannula, and the patient. The pressure may overshoot if the recovery is fast enough, causin~ the mass of the fluid column to oscillate with the compliance of the tubing. The initial negative 2~ pressure-going transient 18 is shown in Fig. le, and the positive pressure transient 20 may help distinguish the negative-going pressure translent sufficiently so that an occlusion is readily identifiable.
A well known feature of a conventional peristaltic pump is its non-uniform flow rate over each cycle, with an actual non-flow period typically over 25 percent of the duty cycle of the pump. This cyclical flow transition period may be minimized in the pump by operating the stepper motor which drives the pump at its ~X;~ll~ rate during the transition phase. It is in this so-called 'Jspeed up" time period where the pinch-off point of the pumping fingers switches from downstream to ~i ~ 2 ~ '7 upstream, opening the pump tubing to the downstream portion of the IV tubing leading to the pressure transducer and the patient. The increase in speed of the motor is synchronized by a rotation sensor, such as a rotating dlsk which rotates in correlation with the rotation of the cam mechanism of the pump, and ~hich bears one or more detectable flags. This switching of pinch-off point from downstream to upstream thereby communicating the upstream pressure to the downstream pressure permits the definition of a detection "window"
where the negative-going transient will occur when there is occlusion upstream of the pump. This narrow window reduces susceptibility of the upstream occlusion detection system to artifact transients, which may, for example, be caused by movement of the IV tubing.
A typical pressure waveform 22 resulting from an upstream occlusion during a flow transition period is illustrated in Fig. 2. The pressure at the beginning cycle is about 20 mmHg at point 24. At point 26 the most downstream finger opens the pumping segment of the tubing to the downstream side and the pressure at the transducer drops sharply. This all occurs within the detection window 30 within the flow transition period 28. The pr ssure drops from the starting pressure 32 during the pressure transient 34 down to the bottom pressure 36.
Fluid begins to flow back during the recovery 38, filling the collapsed pumping segment of the tubing, resulting in the high pressure point or overshoot at 40, followed by the equalization of pressure at 42. A typical pressure ;30 waveform with a total upstream occlusion using a large, lower resistance, metal cannula terminating in a patient line is illustrated in Fig. ~. Superimposed on the chart is the si~nal from a rotation flag sensor 44. As in Fig.
2, the flow transitîon period 46 begins at the positive going edge of this signal, which coincldes with the flag of the rotation flag sensor no longer being detected by a photosensor associated with the rotation flag sensor.
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-, - . ' ' ~ : , :, ' ': , , ' ' . ' ' ' : ' When a neyative-aoing pressure transient 48 occurs during the detection window, the positive-going pressure overshoot transient 50 again follows, as before. Fig. 4 represents a similar pressure waveform for the same condition with a smaller diameter cannula. The rotation flag sensor timing 52 also marks the beginning of the flow transition period 54, during which the negative-going pressure transient 56 occurs, again followed by the recovery 58. In both Fig. 3 and Fig. 4 two negative-going pressure transients are shown. It is apparent thatthe pressure between the flow transition periods is somewhat positive in each case. The pressure falls sharply when the pump tubing opens to the pressure sensor. An important feature of this negative-going pressure transient is an extremely short fall time. The pressure change occurs in less than three sampling periods (15 msecs.) which helps to discriminate against artifact transients because other pressure translents do not change this quickly. Varlance in the duration of the negative transient between Fig. 3 and Fig. 4 is caused by the termination of the tubing with different cannula or needIe sizes. The lower resistance cannula allows fluid to flow back into the pump tubing much faster, enabling the pressure to equalize in a shorter time~
A typical system setup for occlusion sensing is illustrated in Fig. 5. A conventional intravenous fluid bottle 60 is connected with an IV spike and drip chamber 62 through the upstream IV tubing 64 and IV tubing clamp 66 to the peristaltic pump mechanism 68. The peristaltic pump includes the peristaltic pump mechanism and rotation sensor 70, associated with the peristaltic fingers 72, which press upon the fluid line pumping segment 74 placed adjacent the fingers to cause fluid to flow through the line. A convenient placement for the pressure sensor module 76 and the pressure transducer 78 is immediately downstream of the pumping mechanism, within the housing of the peristaltic pump.~ A pressure transducer with negative pressure sensing capability to about -200 mmHg (gauge) is preferred. The downstream tubing 30 includes a cannula or needle 82 at its distal end, suitable for placement in vein of a patient, or in a vein simulator 84, which was used for testing purposes. A rotation sensor signal line 86 carries the rotation sensor signal from the pump and rotation sensor mechanism to an analog to digital converter 90, which is also connected with the pressure signal line 88 to the pressure transducer to receive and digitize the pressure signal as a series of discrete digitized samples, for determination of a downstream pressure parameter by a signal processing unit 92.
The pump rate was found to have an effect on the vacuum ~eing generated with a partial upstream occlusion.
With any given fluid resistance upstream the vacuum will be essentially proportional to the pump rate. This means, that in cases of partial upstream occlusion, at low rates a higher upstream fluid resistance will be tolerated than at high pump rates before an occlusion is detected.
The termination resistance (R~ of the patient tu~ing affects the waveform of the speedup pressure transient. Tests were performed with large, low rasistance cannula (R = 14 m~Hg/liter/hr), a small cannula higher resistance (R = 550 mmHg/liter/hr), and a narrow lumen infusion catheter (R = 1000 mmHg/liter/hr).
The fall time and~ amplitude of the negative-going transient were practically unaffected by the terminating resistance. However, the recovery to the static pressure is strongly dependent on cannula size, and was found to take longer with a hlgher~flow resistance (Fig. 3 and 4).
: ~ The range of -2 to +10 psi (-100 to +500 mmHg) was considered a practical operating region for detectiny ~ 35 upstream occlusion conditions. The full range was tested ;~ ~ with large and small;needle sizes, both occluded and not occluded upstream. A static nPgative pressure of -100 :
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, mmHg takes into account that the pump may be located up to 4 feet above the IV site. The positive pressure is the maximum operating pressure of the pump without going into high pressure alarm.
~hile not intending to be bound by theory, it is believed that the pressure transient amplitude vs. the upstream minus downstream pressure difference appears to be a linear function of this pressure differsntial. Th~
transient amplitude is about 40~ of the pressure differential and is independent of needle size. With an occlusion that reduces the flow rate to 50~ of the selected rate the pressure transient amplitude is alm~st as high as with a total occlusion (zero flow rate). A
typical infusion pump drop rate detector design detects an upstream occlusion when the drop rate is 50% of the selected rate.
The volume of fluid between the pump and the occlusion will affect the amount of fluid that has to be pumped before the negati~e pressure transient will become large enough to be detected. The rate at which this negative pressure waveform builds up is also dependent on the volume and elasticity of the tubing between the pump and the occlusion. The larger and softer that the tubing is the more fluid will have to be pumped for a given negative pressure waveform.
The number of pump rotations necessary for the pressure transient to reach the full amplitude was measured using a standard Ivac infusion set with about 24 inches of vinyl tubing between the drip chamber and the pump. With the occlusion near the pump it takes about 1/2 rotation, and with the occlusion near the drip chamber it takes about two rotations for the pressure transient to become full size. The fact that it takes two rotations of the pump mechanism before the full amplitude appears does not mean that the whole amount of fluid is not being delivered to the patient (0.2 ml).
The pressure transient amplitude has been found to - , .
increase much faster than the pump rate drops off. As an example, when the pressure transient size has reached 50%
(110 mmHg) of the final transient slze (220 mmHg) the pu~p rate has only declined 15%. Fluid will still go to the patient while the vacuum is building up in spite of an upstream occlusion in the tubing.
Fig. 6 shows a time expanded view of an artifact which could produce a ~alse occlusion alarm such as might occur due to patient motion occurring in the detection window. By monitoring the pressure from the start of the non-flow period 110 to the start of the detection window 114, artifacts may be identified. The pressure is fairly constant during this artifact testing time period 112 if no artifacts are present. However, if the pressure should change noticeably, an artifact condition would be suspected and an occlusion alarm could be inhibited. If this condition should exist for more than one or two speedup cycles in a row an alarm indicating the artifact condition could be given. Thus, the pressure measurement between the start of the non-flow period and the start of the detection window can be stored as a threshold value, to determine if a subsequent pressure value in this interval is greater than or equaI to the suspected artifact pressure measurement~ However, in the tests that were performed, the tubing needed to be struck very hard in order to interfere with the detection of an actual transient or cause a false alarm. This would probably not occur under normal conditions such as ambulation of the patient.
One currently preferred method for detecting upstream occlusions involves monitoring the difference in the pressure between two samples which are two sample periods apart (10 ms), and by measuring the pressure level at the start of the detection window and at the bottom of the pressure transient. Decisions will be based on these three values~ The measurement of these values will only be performed during a short time period : ~ .
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defining the detection window in the flow transition period of each duty cycle, from approximately 50 to 100 ms after the start of the flow transition period. These times are specific to the stepping rate of the IVAC 560 pump during the non-flow transition time and they would have to be modified depending on the actual step rate of the motor but in terms of the rotation sensor timing 108, the detection window should always be at the same number of motor steps after the rotation flag of the rotation sensor is no longer detected by the photo sensor. The actual location and width of the detection window may need to be adjusted for each particular type of pump and rotation sensor 108.
Fig. ~ is a flow chart of the method, which was tested with recorded data. The operating range of the transducer was set to -200 to +500 mmHg. At the start 116 of the method, typically all values to be measured are initialized in a central processing unit, such as, for example, the Intel 85. During each cycle of the infusion pump, the start of the non-flow period 118 is determined based upon the tracking of the pump by the rotation sensor. When the start of the non-flow period is determined, a delay of 50ms. past the start of the non-flow period may be used for detecting occlusion artifacts. After 50 ms., the first pressure measurement is taken 122, and compared at 124 with a threshold of -120 mm Hg., for example. If the measured pressure is less than the threshold, the extraordinary reading is determined at 126 to be an artifact, indicating an occlusion can not be reliably detected even if it is present. Otherwise, this first pressure reading is stored in memory locations P0, P1, and P2 as is shown generally at 128. In another aspect of the method, a parameter of the stability of fluid pressure may be determined from pressure measurements taken from the start of the non-flow period during the 50ms. delay.
Such a parameter would be the root mean square of the pressure measurements during this delay interval, and if this root mean were to exceed a reference threshold value, an artifact condition would similarly be indicated.
During the first 50 milliseconds of the non-flow interval, the measured downstream pressure is not being influenced by the flow of fluid and has not yet reached the point at which the vacuum trapped between the upper and lower "fingers" is released. Therefore, this lo interval may be examined to determine if there is a large variation in pressure occurring due to vibration of the tubing or pressure variations caused by patient physiology (coughing, etc.) Such variations could reduce the effectiveness of the detectlon algorithm.
The pressure will be sampled a number (typically 10-20) of times depending on specifics of the mechanism.
From these samples a calculation of signal variability will be made and compared with a threshold. A typical means to determine the variability is the calculation of Root Mean Square power in the signaI. This RMS value is compared with a fixed threshold, and if the R~S value exceeds the threshold, then the measurement is not considered reliable and is not used for alarm purposes.
Determination of the standard deviation of the pressure samples in this pre-transient period may also be used.
Another method involves computing the sum of the absolute difference b~tween successive samples of pressure o~er the interval. This value increases with short term variability just as does the AC RMS or standard deviation calculations but does not require the use of multip~lication and therefore is more readily implemented in small microcomputers.
After the first sample is taken, at the beginning o~ the detection window, the system cycles at 130 to test whether the next sample period of 5ms. has passed. After 5ms., the value of Pl is stored in the memory of the CPU
as P2, the value of P0 is stored as Pl, and a new ''' ~ ' , , .-.: .
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pressure reading of P0 is taken. The difference between P2 and P0 is then compared at 134 with a difference threshold value of 60 mmHg, for example, and if the difference is greater than this 60 mmHg threshold, the value of P0 is compared ~ith a negative pressure th~eshold of -30 mmHg, for example, at 138 to determine whether there has been an occlusion 140. As an alternative, the slope of the pressure transient may be determined from one or more pairs o~ pressure samples, and compared with a slope threshold, to determine whether a sufficiently sharp negative-going transient has occurred to indicate upstream occlusion. The process of measuring and comparing the difference in pressure between two samples two sample periods apart can continue as long as the detection window, at lOOms, has not ended, at 136. After lOOms from the onset of the non-flow period, the detection window is closed, and the system cycles to test for the beginning of the next non-flow period at 118.
20Fig. 8 shows a strip chart recording of a pressure waveform 142 in the upper channel of a sequence of snapshots of the downstream~pressure during consecutive non-flow periods. The lower channel marks the detection window~ period (50 milliseconds). A negative-going 25~ marker ln this time period indicates that an occlusion ' was dete~ted. A positive-going mar~er at the beginning of the detec~ion window 14~ indicates that the transducer pressure was less than -120 mmHg at that moment making it impossible to detect a possible occlusion. This example shows the start of an occlusion 144. In the first non-flow period no translent appears. In the second, a small transi-nt starts showing, but is not large enough to trigger the detection. In the third non~flow period, the transient 148 has grown large enough to be detected. In the following periods No. 4 to 8, the transient is larger and larger and will be detected every time.
~ Another embod;iment of an upstream occlusion : : : : :
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, .. ~ . -detection system is illustrated in ~ig. 9. Thls system is similar in most respects to the system shown in Fig.
5, and accordingly, like or corresponding elements bear like reference numerals. The principal difference in this upstream occlusion detection system is that the pressure signal is transmitted through a delta modulator circuit 157 detecting pressure signals within a frequency band of 5 to 30 Hz. The delta modulator circuit typical y comprises a first low pass filter 151a, receiving the pressure signal via line 88, and functioning to prevent high frequency artifacts from corrupting the detection circuit function. The frequency characteristics of the low pass filter 151a are determined by the upper frequency boundary of the occlusion waveform spectrum, typically 20-30Hz. A second low pass filter 151b, receives the pressure signal via line 88, and operates to provide an output which is essentially a time weighted average of the incoming signal. A comparator 151c receives output from both the first and second low pass filters. The comparator is one having hysteresis which compares the outputs o~ the first and second low pass filters, switching when the difference of the signals changes polarity. Typically this output changes on the positive-going rebound portion of the large transient pressure signal found during a non-flow period when an upstream occlusion exists. The circuit is therefore sensitiv~ to changes in power in this frequency band, indicative of an upstream occlusion waveform occurrence.
The digital output latch 154 detects the rising edge of the output of the comparator, and transmits a digital error signal to be counted by a central processing unit 155, whi.ch in turn executes the reset 156 of the digital output latch 154. The output of the latch is sampled by the cenkral processing unit during the non flow ~ 35 transition period. This limits interfe~ence from noise ; ;and artifacts. The upstream occlusion appears as a sharp negatiYe-going pressure transient during the non flow . - :, -: . .
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transition period, followed by a positive rebound pressure signal. Spectral analysis, such as by Fourier analysis of the pressure waveforms, indicates a noticeable power content increase in frequencies from 5 to 30 Hz during occlusion.
The low pass filters 151a, 151b, the comparator 151c and the latch 154 of the delta modulator 157 thus discriminate power in this frequency band. 'rhe output of the circuit changes a digital level based upon whether the power in the band exceeds the power threshold level, set by the hysteresis of the comparator. The central processing unit includes a counter, which is toggled by the output latch on the transition from low to high count detection, and which will indicate an error when the count exceeds a given threshold value, in the display 158, which may be a chart or a computer monitor, for example. The frequency band can be widaned or narrowed, and a different frequency band for detection can be selected, such as from 40 - 50 Hz. Appropriate self-testing capalbility for calibration purposes may be added,for increased reliability of the system.
In another embodiment, the power in the frequency band of the pressure waveform may be determined by the central processing unit by determining the root mean ~square of the analog signal during the non-flow period, the sum of the sample pressure values minus a baseline or "starting" pressure, or otherwise determining an integral of the measured pressure values during the detection window, and displayed on a display unit 158.
Based upon the foregoing, it can be appreciated that~the method and system for detecting occlusion in a fluid line upstream~ ~of a peristaltic pump in an intravenous fluid administration system provides for a simplified, low cost, way of monitoring upstream occlusion without the necessity o~ modification of existing peristaltic pump~ mechanisms. Placed in a :: :
downstream conflguration, the system of the invention can ~ - .
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Although specific embodiments of the invention have been described and illustrated, it is clear that the invention is susceptible to numerous modifications and adaptations within the ability of those skilled in the art and without the exercise of the inventive faculty.
Thus, it should be understood that various changes in form, detail and uses of the present invention may be made without departing from the spirit and scope of the invention.
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Claims (34)
1. A method for detecting an occlusion in a fluid line upstream of a pump adapted to cause fluid to flow from an upstream portion to a downstream portion of said fluid line, said pump having a cycle with a period during which fluid pressure is communicated from said upstream portion to said downstream portion of said fluid line, the steps of said method comprising:
monitoring fluid pressure in said fluid line downstream of said pump during the period of said pump cycle during which fluid pressure is communicatedfrom said upstream portion to said downstream portion to detect the occurrence of negative-going pressure in said fluid line; and generating a signal indicating an occlusion when negative-going pressure is detected.
monitoring fluid pressure in said fluid line downstream of said pump during the period of said pump cycle during which fluid pressure is communicatedfrom said upstream portion to said downstream portion to detect the occurrence of negative-going pressure in said fluid line; and generating a signal indicating an occlusion when negative-going pressure is detected.
2. The method of claim 1, wherein said signal indicating an occlusion is generated only when said negative-going pressure falls below a negative predetermined pressure threshold.
3. The method of claim 2, wherein said predetermined negative pressure threshold is -30mmHg.
4. The method of any one of claim 1 to 3, wherein said step of monitoring fluid pressure further comprises sampling said fluid pressure at a plurality of times to provide a plurality of pressure samples, determining the difference between two samples which are a predetermined time interval apart, and generating said occlusion signal when said difference is greater than a predetermined difference threshold.
5. The method of claim 4, wherein said difference threshold is about 60mmHg for a predetermined time interval of about 10ms.
6. The method of any one of claims 1 to 5, further comprising the step of determining the slope and amplitude of said negative-going pressure, and generating said occlusion signal only when said slope is greater than a predetermined slope threshold and said negative-going pressure falls below a predetermined pressure threshold.
7. The method of any one of claims 1 to 6, wherein said pump is a peristaltic pump operating on a pumping segment of said fluid line and having a plurality of occluding fingers which move fluid in a peristaltic manner.
8. The method of claim 7, wherein said fluid pressure is monitored during a detection window in each said period of said pump cycle when the most downstream peristaltic finger of said pump opens said pumping segment to the fluid line downstream of said pump.
9. The method of any one of claims 1 to 8, further comprising the step of detecting an artifact condition by monitoring fluid pressure in said fluid line prior to said pump cycle period during which fluid pressure is communicated from said upstream portion to said downstream portion, comparing said monitored pressure to a predetermined artifact minimum pressure threshold and generating an artifact signal when said monitored pressure falls below said artifact threshold.
10. The method of claim 9, wherein the step of detecting said artifact condition comprises determining the amplitude and slope of said fluid pressure, and generating said artifact signal when either said amplitude falls below an artifact minimum pressure threshold, or said slope exceeds an artifact slope threshold.
11. The method of any one of claims 1 to 8, further comprising the step of detecting an artifact condition by monitoring fluid pressure in said fluid line prior to said pump cycle period during which fluid pressure is communicated from said upstream portion to said downstream portion, comparing said monitored pressure to a predetermined artifact minimum pressure threshold hold and inhibiting the generation of said occlusion signal when said monitored pressure falls below said artifact threshold.
12. The method of any one of claims 1 to 11, wherein said negative-going pressure has a waveform comprising a range of frequencies, and further comprising the steps of determining the power content of said negative-going pressure detected over a range of frequencies, comparing said power content with a power content threshold, and generating said occlusion signal when said power content exceeds said power content threshold.
13. The method of claim 12, wherein said power content is determined from the root mean square of said negative-going pressure waveform over said range of frequencies.
14. The method of claim 12 or claim 13, wherein said range of frequencies is from about 5 to about 30Hz.
15. The method of claim 12, wherein said power content is determined from a pressure-time integral of the negative-going pressure waveform with respect to a beginning baseline pressure.
16. A method for detecting an occlusion in a fluid line upstream of a pump adapted to cause fluid to flow from an upstream portion to a downstream portion of said fluid line, said pump having a duty cycle including a transition period in which fluid pressure is communicated from said upstream portion to said downstream portion of said fluid line, the steps of said method comprising:
monitoring fluid pressure in said fluid line downstream of said pump during said transition period to detect the occurrence of a negative-going pressure waveform;
determining the power content of said detected negative-going pressure waveform over a range of frequencies;
comparing said power content with a predetermined power threshold;
and generating an occlusion signal when said waveform power content exceeds said predetermined power threshold.
monitoring fluid pressure in said fluid line downstream of said pump during said transition period to detect the occurrence of a negative-going pressure waveform;
determining the power content of said detected negative-going pressure waveform over a range of frequencies;
comparing said power content with a predetermined power threshold;
and generating an occlusion signal when said waveform power content exceeds said predetermined power threshold.
17. The method of claim 16, wherein said power content is determined from the root mean square of said negative-going pressure waveform over said range of frequencies.
18. The method of claim 16 or claim 17, wherein said range of frequencies is from about 5 to about 30Hz.
19. The method of claim 16, wherein said power content is determined from a pressure-time integral of the negative-going pressure waveform with respect to a beginning baseline pressure.
20. A system for detecting an occlusion in a fluid line upstream of a pump adapted to cause fluid to flow from an upstream portion to a downstream portion of said fluid line, said pump having a cycle with a period during which fluid pressure is communicated from said upstream to said downstream portion of said fluid line, the system comprising:
means for monitoring fluid pressure in said fluid line downstream of said pump during the period of said pump cycle during which fluid is communicated from said upstream portion to said downstream portion to detect the occurrence of negative-going pressure in said fluid line; and means for generating a signal indicating an occlusion when occlusion is detected.
means for monitoring fluid pressure in said fluid line downstream of said pump during the period of said pump cycle during which fluid is communicated from said upstream portion to said downstream portion to detect the occurrence of negative-going pressure in said fluid line; and means for generating a signal indicating an occlusion when occlusion is detected.
21. The system of claim 20, wherein said signal indicating an occlusion is generated only when said negative-going pressure falls below a predetermined negative pressure threshold.
22. The system of claim 20, wherein said means for monitoring fluid pressure further comprises means for sampling said fluid pressure at a plurality of times to provide a plurality of pressure samples, means for determining the difference between two samples which are a predetermined time interval apart, and means for generating said occlusion signal when said difference is greater than a predetermined difference threshold.
23. The system of any one of claims 20 to 23, further comprising means for determining the slope and amplitude of said negative pressure, and means for generating said occlusion signal only when said slope is greater than a predetermined slope threshold and said negative-going pressure falls below a predetermined pressure threshold.
24. The system of claim 20, wherein said pump is a peristaltic pump operating on a pumping segment of said fluid line and having a plurality of fingers which move fluid in a peristaltic manner.
25. The system of claim 24, wherein said fluid pressure is monitored during a detection window in each said period of said pump cycle when the most downstream peristaltic finger of said pump opens said pumping segment to the fluid line downstream of said pump.
26. In an intravenous fluid administration system including a fluid line, and a pump adapted to cause fluid to flow from an upstream portion to a downstream portion of said fluid line, said pump having a duty cycle with a cyclical flow transition period during which fluid pressure is communicated downstream to induce a negative pressure transient downstream of said pump when an occlusion exists in said fluid line upstream of said pump, an upstream occlusion detection system comprising the combination of:
a pressure detector for measuring fluid pressure in said fluid line at a location downstream of said pump;
means for monitoring said fluid pressure in said fluid line downstream of said pump during said flow transition period to detect the occurrence of each negative-going pressure transient; and means for generating an occlusion signal indicating an occlusion condition upstream of said pump when a said negative pressure transient is detected.
a pressure detector for measuring fluid pressure in said fluid line at a location downstream of said pump;
means for monitoring said fluid pressure in said fluid line downstream of said pump during said flow transition period to detect the occurrence of each negative-going pressure transient; and means for generating an occlusion signal indicating an occlusion condition upstream of said pump when a said negative pressure transient is detected.
27. The combination of claim 26, further comprising means for determining the amplitude of each negative-going pressure transient, and said occlusion signal generating means being operative to generate said occlusion signal only when said amplitude falls below a minimum pressure threshold.
28. The combination of claim 26, wherein said means for monitoring said fluid pressure further comprises means for providing a plurality of pressure samples, means for determining the difference between two samples a predetermined time interval apart for at least one pair of said pressure samples, and said means for generating said occlusion signal being operative to generate said occlusion signal when said difference is greater than a predetermined difference threshold.
29. The combination of claim 26, further comprising means for determining the slope and amplitude of each said negative pressure transient, and said means for generating said occlusion signal being operative to generate said occlusion signal only when said slope is greater than a predetermined slope threshold and said amplitude falls below a predetermined minimum pressure threshold.
30. The combination of any one of claims 26 to 29, further comprising means for detecting an artifact condition by monitoring fluid pressure in said fluid line prior to said pump cycle period during which fluid pressure is communicated from said upstream portion to said downstream portion, means for comparing said monitored pressure to a predetermined artifact minimum pressure threshold and means for generating an artifact signal when said monitored pressure falls below said artifact threshold.
31. The combination of any one of claims 26 to 29, further comprising means for detecting an artifact condition by monitoring fluid pressure in said fluid line prior to said pump cycle period during which fluid pressure is communicated from said upstream portion to said downstream portion, means for comparing said monitored pressure to a predetermined artifact minimum pressure threshold and means for inhibiting the generation of said occlusion signal when said monitored pressure falls below said artifact threshold.
32. The combination of claim 26, wherein each negative-going pressure transient has a waveform over a range of frequencies, and further comprising means for determining power content of each said negative-going pressure transient detected over a range of frequencies, means for comparing said power content with a power threshold, and said means for generating said occlusion signal being operative to generate said occlusion signal only when said power content exceeds said power threshold.
33. In a system for detecting an occlusion in a fluid line wherein a pump operates on said fluid line to cause fluid to flow from an upstream portion to a downstream portion of said fluid line, said pump having a cycle with a non-flow transition period during which fluid pressure is communicated from said upstream portion to said downstream portion of said fluid line, the combination comprising:
means for monitoring fluid pressure in said fluid line downstream of said pump during said non-flow transition period to detect the occurrence of a negative-going pressure transient; and means for determining power content of each said negative-going pressure transient detected over a range of frequencies, comparing said power content with a power threshold, and generating an occlusion signal when said power content exceeds said power threshold.
means for monitoring fluid pressure in said fluid line downstream of said pump during said non-flow transition period to detect the occurrence of a negative-going pressure transient; and means for determining power content of each said negative-going pressure transient detected over a range of frequencies, comparing said power content with a power threshold, and generating an occlusion signal when said power content exceeds said power threshold.
34. The method of any one of claims 1 to 9, further comprising the step of monitoring fluid pressure during said period in an interval of non-flow prior to communication of said fluid pressure from said upstream portion to said downstream portion of said fluid line, determining a parameter of the variability of fluid pressure during said interval, and generating an artifact signal when said parameter of variability of fluid pressure exceeds a predefined threshold.
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|---|---|---|---|
| US433,627 | 1989-11-08 | ||
| US07/433,627 US5096385A (en) | 1989-11-08 | 1989-11-08 | Method and system for upstream occlusion detection |
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|---|---|
| CA2029267A1 CA2029267A1 (en) | 1991-05-09 |
| CA2029267C true CA2029267C (en) | 1998-07-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002029267A Expired - Lifetime CA2029267C (en) | 1989-11-08 | 1990-11-02 | Method and system for upstream occlusion detection |
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| US (1) | US5096385A (en) |
| EP (1) | EP0431310B1 (en) |
| CA (1) | CA2029267C (en) |
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| HK (1) | HK1006006A1 (en) |
Families Citing this family (144)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6241704B1 (en) | 1901-11-22 | 2001-06-05 | Sims Deltec, Inc. | Drug pump systems and methods |
| US5935099A (en) | 1992-09-09 | 1999-08-10 | Sims Deltec, Inc. | Drug pump systems and methods |
| US5803712A (en) | 1988-05-17 | 1998-09-08 | Patient Solutions, Inc. | Method of measuring an occlusion in an infusion device with disposable elements |
| US5186431A (en) * | 1989-09-22 | 1993-02-16 | Yehuda Tamari | Pressure sensitive valves for extracorporeal circuits |
| US5213573A (en) * | 1991-08-05 | 1993-05-25 | Imed Corporation | Iv administration set infiltration monitor |
| DE69315450T2 (en) * | 1992-01-22 | 1998-05-20 | Alaris Medical Systems Inc N D | Condition determination of a liquid hose line |
| US5419684A (en) * | 1993-06-14 | 1995-05-30 | Minnesota Mining And Manufacturing Company | Infusion pump with reversible motor and method of use |
| US5827219A (en) * | 1993-10-28 | 1998-10-27 | Medrad, Inc. | Injection system and pumping system for use therein |
| US5695473A (en) * | 1994-07-27 | 1997-12-09 | Sims Deltec, Inc. | Occlusion detection system for an infusion pump |
| US5803917A (en) * | 1994-09-13 | 1998-09-08 | Alaris Medical Systems, Inc. | Fluid flow resistance monitoring system |
| US6213972B1 (en) | 1994-09-13 | 2001-04-10 | Alaris Medical Systems, Inc. | Fluid flow resistance monitoring system |
| US5514102A (en) * | 1995-05-05 | 1996-05-07 | Zevex Incorporated | Pressure monitoring enteral feeding system and method |
| US5827223A (en) | 1995-08-31 | 1998-10-27 | Alaris Medical Systems, Inc. | Upstream occulsion detection system |
| US5853386A (en) | 1996-07-25 | 1998-12-29 | Alaris Medical Systems, Inc. | Infusion device with disposable elements |
| US6158965A (en) * | 1996-07-30 | 2000-12-12 | Alaris Medical Systems, Inc. | Fluid flow resistance monitoring system |
| US5738103A (en) * | 1996-07-31 | 1998-04-14 | Medwave, Inc. | Segmented estimation method |
| US5954485A (en) * | 1996-08-14 | 1999-09-21 | Sims Deltec, Inc. | Free-flow protection devices and methods |
| US5906589A (en) * | 1996-11-13 | 1999-05-25 | Cobe Laboratories, Inc. | Method and apparatus for occlusion monitoring using pressure waveform analysis |
| US6056522A (en) * | 1998-05-13 | 2000-05-02 | Sims Deltec, Inc. | Reusable cassette with a moveable door |
| US7766873B2 (en) | 1998-10-29 | 2010-08-03 | Medtronic Minimed, Inc. | Method and apparatus for detecting occlusions in an ambulatory infusion pump |
| US7621893B2 (en) * | 1998-10-29 | 2009-11-24 | Medtronic Minimed, Inc. | Methods and apparatuses for detecting occlusions in an ambulatory infusion pump |
| US6077055A (en) * | 1998-12-03 | 2000-06-20 | Sims Deltec, Inc. | Pump system including cassette sensor and occlusion sensor |
| FR2790041B1 (en) * | 1999-02-23 | 2002-01-18 | Fresenius Vial | METHOD FOR CONTROLLING A PUMPING DEVICE COMPRISING A PUMP PROVIDED WITH A FLEXIBLE TUBE AND DEVICE FOR IMPLEMENTING THE METHOD |
| US6423029B1 (en) * | 1999-04-29 | 2002-07-23 | Medtronic, Inc. | System and method for detecting abnormal medicament pump fluid pressure |
| US7255680B1 (en) | 1999-10-27 | 2007-08-14 | Cardinal Health 303, Inc. | Positive pressure infusion system having downstream resistance measurement capability |
| US6485465B2 (en) * | 2000-03-29 | 2002-11-26 | Medtronic Minimed, Inc. | Methods, apparatuses, and uses for infusion pump fluid pressure and force detection |
| US6985870B2 (en) * | 2002-01-11 | 2006-01-10 | Baxter International Inc. | Medication delivery system |
| US10173008B2 (en) | 2002-01-29 | 2019-01-08 | Baxter International Inc. | System and method for communicating with a dialysis machine through a network |
| US8775196B2 (en) * | 2002-01-29 | 2014-07-08 | Baxter International Inc. | System and method for notification and escalation of medical data |
| US8250483B2 (en) | 2002-02-28 | 2012-08-21 | Smiths Medical Asd, Inc. | Programmable medical infusion pump displaying a banner |
| US8504179B2 (en) | 2002-02-28 | 2013-08-06 | Smiths Medical Asd, Inc. | Programmable medical infusion pump |
| US8234128B2 (en) | 2002-04-30 | 2012-07-31 | Baxter International, Inc. | System and method for verifying medical device operational parameters |
| US20040133166A1 (en) * | 2002-11-22 | 2004-07-08 | Minimed Inc. | Methods, apparatuses, and uses for infusion pump fluid pressure and force detection |
| US9033920B2 (en) * | 2003-10-02 | 2015-05-19 | Medtronic, Inc. | Determining catheter status |
| US8323244B2 (en) * | 2007-03-30 | 2012-12-04 | Medtronic, Inc. | Catheter malfunction determinations using physiologic pressure |
| US7320676B2 (en) * | 2003-10-02 | 2008-01-22 | Medtronic, Inc. | Pressure sensing in implantable medical devices |
| US9138537B2 (en) * | 2003-10-02 | 2015-09-22 | Medtronic, Inc. | Determining catheter status |
| US7886579B2 (en) * | 2003-10-09 | 2011-02-15 | Endress + Hauser Wetzer Gmbh + Co. Kg | Portable sampler |
| US8182461B2 (en) * | 2003-11-04 | 2012-05-22 | Smiths Medical Asd, Inc. | Syringe pump rapid occlusion detection system |
| US7255683B2 (en) * | 2003-12-31 | 2007-08-14 | Cardinal Health 303, Inc. | System for detecting the status of a vent associated with a fluid supply upstream of an infusion pump |
| US7206715B2 (en) * | 2003-12-31 | 2007-04-17 | Cardinal Health 303, Inc. | Empty container detection using container side pressure sensing |
| US8672875B2 (en) | 2003-12-31 | 2014-03-18 | Carefusion 303, Inc. | Medication safety enhancement for secondary infusion |
| US8954336B2 (en) | 2004-02-23 | 2015-02-10 | Smiths Medical Asd, Inc. | Server for medical device |
| DE102004019053A1 (en) * | 2004-04-20 | 2005-11-24 | Disetronic Licensing Ag | Apparatus and method for occlusion detection in infusion pumps |
| IL165365A0 (en) | 2004-11-24 | 2006-01-15 | Q Core Ltd | Finger-type peristaltic pump |
| US8308457B2 (en) * | 2004-11-24 | 2012-11-13 | Q-Core Medical Ltd. | Peristaltic infusion pump with locking mechanism |
| US7318353B2 (en) * | 2004-12-22 | 2008-01-15 | Lancer Partnership Ltd. | Method and apparatus for a product displacement sensing device |
| EP2030643A1 (en) * | 2006-04-06 | 2009-03-04 | Medtronic, Inc. | Systems and methods for identifying catheter malfunctions using pressure sensing |
| US8965707B2 (en) | 2006-08-03 | 2015-02-24 | Smiths Medical Asd, Inc. | Interface for medical infusion pump |
| US8858526B2 (en) | 2006-08-03 | 2014-10-14 | Smiths Medical Asd, Inc. | Interface for medical infusion pump |
| US8149131B2 (en) | 2006-08-03 | 2012-04-03 | Smiths Medical Asd, Inc. | Interface for medical infusion pump |
| US8435206B2 (en) | 2006-08-03 | 2013-05-07 | Smiths Medical Asd, Inc. | Interface for medical infusion pump |
| IL179231A0 (en) | 2006-11-13 | 2007-03-08 | Q Core Ltd | A finger-type peristaltic pump comprising a ribbed anvil |
| US8535025B2 (en) | 2006-11-13 | 2013-09-17 | Q-Core Medical Ltd. | Magnetically balanced finger-type peristaltic pump |
| IL179234A0 (en) * | 2006-11-13 | 2007-03-08 | Q Core Ltd | An anti-free flow mechanism |
| MX2009005416A (en) * | 2006-11-21 | 2009-08-07 | Baxter Int | System and method for remote monitoring and/or management of infusion therapies. |
| US9044537B2 (en) | 2007-03-30 | 2015-06-02 | Medtronic, Inc. | Devices and methods for detecting catheter complications |
| GB0712737D0 (en) * | 2007-07-02 | 2007-08-08 | Smith & Nephew | Apparatus |
| GB0715212D0 (en) * | 2007-08-06 | 2007-09-12 | Smith & Nephew | Apparatus |
| US8062008B2 (en) * | 2007-09-27 | 2011-11-22 | Curlin Medical Inc. | Peristaltic pump and removable cassette therefor |
| US8083503B2 (en) * | 2007-09-27 | 2011-12-27 | Curlin Medical Inc. | Peristaltic pump assembly and regulator therefor |
| US7934912B2 (en) * | 2007-09-27 | 2011-05-03 | Curlin Medical Inc | Peristaltic pump assembly with cassette and mounting pin arrangement |
| DE102007049446A1 (en) * | 2007-10-16 | 2009-04-23 | Cequr Aps | Catheter introducer |
| US9026370B2 (en) | 2007-12-18 | 2015-05-05 | Hospira, Inc. | User interface improvements for medical devices |
| US8133197B2 (en) | 2008-05-02 | 2012-03-13 | Smiths Medical Asd, Inc. | Display for pump |
| US10089443B2 (en) | 2012-05-15 | 2018-10-02 | Baxter International Inc. | Home medical device systems and methods for therapy prescription and tracking, servicing and inventory |
| US8057679B2 (en) | 2008-07-09 | 2011-11-15 | Baxter International Inc. | Dialysis system having trending and alert generation |
| EP2158930B1 (en) * | 2008-08-27 | 2017-06-28 | F. Hoffmann-La Roche AG | Flow control valves for leakage detection, free-flow prevention and occlusion detection |
| US8554579B2 (en) | 2008-10-13 | 2013-10-08 | Fht, Inc. | Management, reporting and benchmarking of medication preparation |
| US20100185517A1 (en) * | 2009-01-21 | 2010-07-22 | Yahoo! Inc. | User interface for interest-based targeted marketing |
| US8378837B2 (en) * | 2009-02-20 | 2013-02-19 | Hospira, Inc. | Occlusion detection system |
| CA2769030C (en) | 2009-07-30 | 2016-05-10 | Tandem Diabetes Care, Inc. | Infusion pump system with disposable cartridge having pressure venting and pressure feedback |
| US8547239B2 (en) | 2009-08-18 | 2013-10-01 | Cequr Sa | Methods for detecting failure states in a medicine delivery device |
| US8672873B2 (en) * | 2009-08-18 | 2014-03-18 | Cequr Sa | Medicine delivery device having detachable pressure sensing unit |
| US8142400B2 (en) * | 2009-12-22 | 2012-03-27 | Q-Core Medical Ltd. | Peristaltic pump with bi-directional pressure sensor |
| US8371832B2 (en) * | 2009-12-22 | 2013-02-12 | Q-Core Medical Ltd. | Peristaltic pump with linear flow control |
| WO2011116233A1 (en) * | 2010-03-17 | 2011-09-22 | Georgia Tech Research Corporation | Valveless pump |
| WO2011128850A2 (en) | 2010-04-12 | 2011-10-20 | Q Core Medical Ltd | Air trap for intravenous pump |
| US8486020B2 (en) | 2010-08-11 | 2013-07-16 | Zevex, Inc. | Pressure sensor and method of use |
| AU2011308700B2 (en) | 2010-10-01 | 2015-04-02 | Zevex, Inc. | Pressure sensor seal and method of use |
| US9004886B2 (en) | 2010-10-01 | 2015-04-14 | Zevex, Inc. | Pressure monitoring system for infusion pumps |
| US9211378B2 (en) | 2010-10-22 | 2015-12-15 | Cequr Sa | Methods and systems for dosing a medicament |
| US9674811B2 (en) | 2011-01-16 | 2017-06-06 | Q-Core Medical Ltd. | Methods, apparatus and systems for medical device communication, control and localization |
| WO2013001425A2 (en) | 2011-06-27 | 2013-01-03 | Q-Core Medical Ltd. | Methods, circuits, devices, apparatuses, encasements and systems for identifying if a medical infusion system is decalibrated |
| US9240002B2 (en) | 2011-08-19 | 2016-01-19 | Hospira, Inc. | Systems and methods for a graphical interface including a graphical representation of medical data |
| US10022498B2 (en) | 2011-12-16 | 2018-07-17 | Icu Medical, Inc. | System for monitoring and delivering medication to a patient and method of using the same to minimize the risks associated with automated therapy |
| US9101712B2 (en) * | 2012-03-09 | 2015-08-11 | Zevex, Inc. | Occlusion detection method |
| AU2013239778B2 (en) | 2012-03-30 | 2017-09-28 | Icu Medical, Inc. | Air detection system and method for detecting air in a pump of an infusion system |
| US9180242B2 (en) | 2012-05-17 | 2015-11-10 | Tandem Diabetes Care, Inc. | Methods and devices for multiple fluid transfer |
| CA3109632C (en) * | 2012-05-24 | 2023-09-05 | Deka Products Limited Partnership | Apparatus for infusing fluid |
| US9555186B2 (en) | 2012-06-05 | 2017-01-31 | Tandem Diabetes Care, Inc. | Infusion pump system with disposable cartridge having pressure venting and pressure feedback |
| CA3089257C (en) | 2012-07-31 | 2023-07-25 | Icu Medical, Inc. | Patient care system for critical medications |
| SG11201501427PA (en) | 2012-08-31 | 2015-03-30 | Baxter Corp Englewood | Medication requisition fulfillment system and method |
| ES2675788T3 (en) * | 2012-10-12 | 2018-07-12 | Becton, Dickinson And Company | System and method for detecting occlusions in a medication infusion system using pulsating pressure signals |
| NZ707430A (en) | 2012-10-26 | 2016-04-29 | Baxter Corp Englewood | Improved work station for medical dose preparation system |
| CA2889210C (en) | 2012-10-26 | 2020-12-15 | Baxter Corporation Englewood | Improved image acquisition for medical dose preparation system |
| EP2948204B1 (en) | 2013-01-28 | 2021-08-25 | Smiths Medical ASD, Inc. | Medication safety devices and methods |
| US9855110B2 (en) | 2013-02-05 | 2018-01-02 | Q-Core Medical Ltd. | Methods, apparatus and systems for operating a medical device including an accelerometer |
| US20140236119A1 (en) * | 2013-02-15 | 2014-08-21 | Micrel Medical Devices S.A. | Method for Processing Infusion Data and an Infusion Pump System |
| US9173998B2 (en) | 2013-03-14 | 2015-11-03 | Tandem Diabetes Care, Inc. | System and method for detecting occlusions in an infusion pump |
| US9180243B2 (en) * | 2013-03-15 | 2015-11-10 | Tandem Diabetes Care, Inc. | Detection of infusion pump conditions |
| AU2014268355B2 (en) | 2013-05-24 | 2018-06-14 | Icu Medical, Inc. | Multi-sensor infusion system for detecting air or an occlusion in the infusion system |
| CA2913915C (en) | 2013-05-29 | 2022-03-29 | Hospira, Inc. | Infusion system which utilizes one or more sensors and additional information to make an air determination regarding the infusion system |
| CA2913918C (en) | 2013-05-29 | 2022-02-15 | Hospira, Inc. | Infusion system and method of use which prevents over-saturation of an analog-to-digital converter |
| JP7025118B2 (en) * | 2013-08-29 | 2022-02-24 | モータス ジーアイ メディカル テクノロジーズ リミテッド | Colon cleaning system with self-cleaning properties |
| JP6478999B2 (en) | 2013-11-21 | 2019-03-06 | モータス・ジィ・アイ・メディカル・テクノロジーズ・リミテッドＭｏｔｕｓ Ｇｉ Ｍｅｄｉｃａｌ Ｔｅｃｈｎｏｌｏｇｉｅｓ Ｌｔｄ． | Distal front end for position adjustment of endoscope with suction device |
| US9949618B2 (en) | 2013-11-21 | 2018-04-24 | Motus Gi Medical Technologies Ltd. | Apparatus and method for coupling between a colonoscope and add-on tubes |
| DE102013113387A1 (en) * | 2013-12-03 | 2015-06-03 | Ulrich Gmbh & Co. Kg | Injector for injecting a fluid and method for controlling an injector |
| US20150182698A1 (en) | 2013-12-31 | 2015-07-02 | Abbvie Inc. | Pump, motor and assembly for beneficial agent delivery |
| ES2776363T3 (en) | 2014-02-28 | 2020-07-30 | Icu Medical Inc | Infusion set and method using dual wavelength in-line optical air detection |
| WO2015155776A2 (en) | 2014-04-09 | 2015-10-15 | Motus Gi Medical Technologies Ltd. | Cleaning method for prepless colonoscopy |
| AU2015266706B2 (en) | 2014-05-29 | 2020-01-30 | Icu Medical, Inc. | Infusion system and pump with configurable closed loop delivery rate catch-up |
| JP5995915B2 (en) | 2014-06-30 | 2016-09-21 | ミネベア株式会社 | Occlusion detection device, infusion device, and operation method of occlusion detection device |
| WO2016003902A1 (en) | 2014-06-30 | 2016-01-07 | Baxter Corporation Englewood | Managed medical information exchange |
| US10227971B2 (en) | 2014-08-12 | 2019-03-12 | Kpr U.S., Llc | Downstream flow detection system for flow control apparatus |
| US10531799B2 (en) * | 2014-09-12 | 2020-01-14 | Vanderbilt University | Intravenous access device detecting intravenous infiltration and in-vein placement |
| US11107574B2 (en) | 2014-09-30 | 2021-08-31 | Baxter Corporation Englewood | Management of medication preparation with formulary management |
| US11575673B2 (en) | 2014-09-30 | 2023-02-07 | Baxter Corporation Englewood | Central user management in a distributed healthcare information management system |
| AU2015358483A1 (en) | 2014-12-05 | 2017-06-15 | Baxter Corporation Englewood | Dose preparation data analytics |
| US11344668B2 (en) | 2014-12-19 | 2022-05-31 | Icu Medical, Inc. | Infusion system with concurrent TPN/insulin infusion |
| US10220132B2 (en) | 2014-12-19 | 2019-03-05 | Fenwal, Inc. | Biological fluid flow control apparatus and method |
| MX2017010008A (en) * | 2015-02-03 | 2017-11-22 | Univ Vanderbilt | Intravenous access device detecting intravenous infiltration and in-vein placement. |
| US10850024B2 (en) | 2015-03-02 | 2020-12-01 | Icu Medical, Inc. | Infusion system, device, and method having advanced infusion features |
| CA2978455A1 (en) | 2015-03-03 | 2016-09-09 | Baxter Corporation Englewood | Pharmacy workflow management with integrated alerts |
| CA2985719C (en) | 2015-06-25 | 2024-03-26 | Gambro Lundia Ab | Medical device system and method having a distributed database |
| US20170049959A1 (en) * | 2015-08-20 | 2017-02-23 | Sorrel Medical Ltd. | Automatic Catheter Recognition and Associated Methods, Systems and Circuits |
| CN105396200B (en) * | 2015-12-08 | 2021-11-05 | 深圳迈瑞科技有限公司 | Infusion pump and method and device for alarming blockage on infusion pipeline of infusion pump |
| AU2017264784B2 (en) | 2016-05-13 | 2022-04-21 | Icu Medical, Inc. | Infusion pump system and method with common line auto flush |
| EP3468635A4 (en) | 2016-06-10 | 2019-11-20 | ICU Medical, Inc. | Acoustic flow sensor for continuous medication flow measurements and feedback control of infusion |
| US10485926B2 (en) * | 2016-10-07 | 2019-11-26 | Carefusion 303, Inc. | Systems and methods for controlling an infusion pump |
| KR20190094214A (en) | 2016-12-15 | 2019-08-12 | 백스터 인터내셔널 인코포레이티드 | System and method for monitoring and determining patient parameters from sensed vein waveforms |
| AU2017381172A1 (en) | 2016-12-21 | 2019-06-13 | Gambro Lundia Ab | Medical device system including information technology infrastructure having secure cluster domain supporting external domain |
| US10089055B1 (en) | 2017-12-27 | 2018-10-02 | Icu Medical, Inc. | Synchronized display of screen content on networked devices |
| US11039754B2 (en) | 2018-05-14 | 2021-06-22 | Baxter International Inc. | System and method for monitoring and determining patient parameters from sensed venous waveform |
| EP3836982B1 (en) | 2018-08-16 | 2024-01-17 | Motus GI Medical Technologies Ltd. | Integrated endoscope cleansing system |
| CA3116182A1 (en) * | 2018-10-15 | 2020-04-23 | Carefusion 303, Inc. | Pump flow adjusting system |
| IL273061B2 (en) | 2019-03-04 | 2024-01-01 | Avoset Health Ltd | In cycle pressure measurement |
| WO2020178827A1 (en) | 2019-03-05 | 2020-09-10 | Avoset Health Ltd. | Anti-free-flow valve |
| US11540777B2 (en) | 2019-04-02 | 2023-01-03 | Baxter International Inc. | Removable fluid sensor in an administration set |
| EP3825662B1 (en) | 2019-11-18 | 2022-11-16 | Eitan Medical Ltd. | Fast test for medical pump |
| US11278671B2 (en) | 2019-12-04 | 2022-03-22 | Icu Medical, Inc. | Infusion pump with safety sequence keypad |
| AU2021311443A1 (en) | 2020-07-21 | 2023-03-09 | Icu Medical, Inc. | Fluid transfer devices and methods of use |
| US11135360B1 (en) | 2020-12-07 | 2021-10-05 | Icu Medical, Inc. | Concurrent infusion with common line auto flush |
| CN115096501B (en) * | 2022-06-29 | 2023-06-09 | 深圳赛桥生物创新技术有限公司 | Pipeline positive pressure threshold value determination and abnormality warning method, controller, system and medium |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3942526A (en) * | 1972-03-03 | 1976-03-09 | Wilder Joseph R | Alarm system for intravenous infusion procedure |
| US4236880A (en) * | 1979-03-09 | 1980-12-02 | Archibald Development Labs, Inc. | Nonpulsating IV pump and disposable pump chamber |
| JPS56113083A (en) * | 1980-02-12 | 1981-09-05 | Terumo Corp | Choke detection method and device for peristaltic liquid pump |
| US4394862A (en) * | 1980-08-25 | 1983-07-26 | Baxter Travenol Laboratories, Inc. | Metering apparatus with downline pressure monitoring system |
| US4563179A (en) * | 1982-04-28 | 1986-01-07 | Sharp Kabushiki Kaisha | Blocking condition detection device in a fluid injection system |
| US4534756A (en) * | 1983-04-11 | 1985-08-13 | Ivac Corporation | Fault detection apparatus and method for parenteral infusion system |
| US4526574A (en) * | 1983-05-23 | 1985-07-02 | Baxter Travenol Laboratories, Inc. | Differential occlusion sensing method and apparatus |
| US4530696A (en) * | 1983-06-13 | 1985-07-23 | Institute Of Critical Care Medicine | Monitor for intravenous injection system for detecting occlusion and/or infiltration |
| IT8453709V0 (en) * | 1984-08-07 | 1984-08-07 | Hospal Dasco Spa | PERFECTED TYPE EQUIPMENT FOR THE CIRCULATION OF A LIQUID ALONG A TUBULAR LINE |
| US4690673A (en) * | 1985-11-26 | 1987-09-01 | Imed Corporation | Dual mode I.V. infusion device with distal sensor |
| US4617014A (en) * | 1985-11-26 | 1986-10-14 | Warner-Lambert Company | Dual mode I. V. infusion device |
| US4648869A (en) * | 1985-12-04 | 1987-03-10 | American Hospital Supply Corporation | Automatic infiltration detection system and method |
| US4778451A (en) * | 1986-03-04 | 1988-10-18 | Kamen Dean L | Flow control system using boyle's law |
| US4710163A (en) * | 1986-06-06 | 1987-12-01 | Ivac Corporation | Detection of fluid flow faults in the parenteral administration of fluids |
| US4747828A (en) * | 1986-12-09 | 1988-05-31 | Fisher Scientific Group | IV fluid line occlusion detector |
| US4836752A (en) * | 1987-11-02 | 1989-06-06 | Fisher Scientific Company | Partial restriction detector |
| US4863425A (en) * | 1987-12-04 | 1989-09-05 | Pacesetter Infusion, Ltd. | Patient-side occlusion detection system for a medication infusion system |
| US4846792A (en) * | 1988-03-08 | 1989-07-11 | Baxter International Inc. | Automatic infiltration detection system and method |
| US4950235A (en) * | 1988-05-10 | 1990-08-21 | Pacesetter Infusion, Ltd. | Container-side occlusion detection system for a medication infusion system |
-
1989
- 1989-11-08 US US07/433,627 patent/US5096385A/en not_active Expired - Lifetime
-
1990
- 1990-10-30 EP EP90120828A patent/EP0431310B1/en not_active Expired - Lifetime
- 1990-10-30 DE DE69024923T patent/DE69024923T2/en not_active Expired - Lifetime
- 1990-11-02 CA CA002029267A patent/CA2029267C/en not_active Expired - Lifetime
-
1998
- 1998-06-10 HK HK98105095A patent/HK1006006A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| US5096385A (en) | 1992-03-17 |
| EP0431310A1 (en) | 1991-06-12 |
| DE69024923T2 (en) | 1996-09-05 |
| CA2029267A1 (en) | 1991-05-09 |
| HK1006006A1 (en) | 1999-02-05 |
| DE69024923D1 (en) | 1996-02-29 |
| EP0431310B1 (en) | 1996-01-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |