WO2004041081A1

WO2004041081A1 - Functional isolation of upgradeable components to reduce risk in medical treatment devices

Info

Publication number: WO2004041081A1
Application number: PCT/US2003/035000
Authority: WO
Inventors: Dennis Treu; Kevin Albiston; Barry Fulkerson; Jeffrey Burbank
Original assignee: Nxstage Medical, Inc.
Priority date: 2002-11-01
Filing date: 2003-11-03
Publication date: 2004-05-21
Also published as: AU2003287486A1

Abstract

A medical treatment system isolates more risk-sensitive equipment from less risk-sensitive components of a treatment device to allow upgrades to be made to the latter more easily without an concomitant increase in risk to a patient caused by upgrades. For example, the latter may serve a pure monitoring function while the former encapsulates the treatment functions thereby preventing errors from the latter from propagating into the treatment-sensitive portions of the device.

Description

TITLE

FUNCTIONAL ISOLATION OF UPGRADEABLE COMPONENTS TO REDUCE RISK IN MEDICAL TREATMENT DEVICES

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority to US Patent Application Serial Number 60/423,318, entitled November 1, 2002, which application is hereby incorporated by reference as if fully set forth in its entirety herein.

BACKGROUND OF THE INVENTION [0002] Medical devices are instrumental in saving or prolonging countless lives. Examples of medical devices include dialysis machines, heart lung machines, respirators, electrocardiogram machines, defibrillators, and pacemakers. Because human lives are at stake, it is of critical importance to avoid malfunctions in such medical devices . Many medical treatment systems may benefit from frequent upgrades of their capabilities, but such upgrades can run the risk of modifying the behavior of treatment systems in unexpected ways, creating risk. For example, many sophisticated treatment devices such renal replacement therapy machines employ software in their control and performance monitoring mechanisms. Software is easily modified, but can profoundly impact safety. In its General Principles of Software Validation; Final Guidance for Industry and FDA Staff Document issued on: January 11, 2002, the Food and Drug Administration (FDA) reported its analysis of 3140 medical device recalls conducted between 1992 and 1998, which revealed 7.7% were attributable to software failures. Of those software related recalls, 79% were caused by software defects that were introduced when changes were made to the software after its initial production and distribution.

[0003] In addition to the risk, government regulation of medical devices make upgrades expensive for manufacturers and vendors and impose delays in the introduction of improved systems. To protect the public from failures caused by system upgrades, governments often regulate the sale and use of medical devices and require additional testing and proof of safety every time a treatment device is modified. When a manufacturer wishes to release an improved version of a device, the manufacturer must go through expensive, and time- consuming regulatory approval process to establish the efficacy and safety of the improvements. Because of this, many patients are deprived from the benefits that recent advances in medical technology might otherwise provide. In regimes where such testing is not onerous, the risk is still present.

SUMMARY OF THE INVENTION [0004] Instead of designing a medical device that must be upgraded in order to add improvements, the inventors have recognized that upgradeability can be obtained by separating portions of a medical treatment device with differing tendencies to impact safety or performance so as to isolate the risks of making upgrades. For example, a machine may be divided by a first component that includes critical treatment actuators and sensors and which is operable as a stand-alone device and a second component that includes data logging, data reduction, display, and various non-critical annunciator functions. These may be termed a treatment device and an auxiliary status-reporting device (ASRD), for convenience. In such a system, the two may be mechanically separated such that the medical device transmits information to the ASRD by a one-way communications channel to ensure that there is no way for the latter to affect the state of the former. In such an embodiment, this information would let the ASRD know what is going on inside the medical device. The ASRD may manipulate this information and report the status of the medical device to an operator. In this example, notably, the ASRD does not control the medical device. Control of the medical device can only be accomplished by manipulating the controls on the medical device itself.

[0005] Preferably, the transfer of information occurs in one direction only -- from the medical device to the ASRD. It is possible to exchange information if care is taken to ensure that an error condition in the ASRD cannot propagate into an error condition in the medical device. Alternatively, layers of operation may be defined to ensure that errors cannot propagate into critical subsystems. In a preferred embodiment, no information flows back from the ASRD to the medical device. In this case, it becomes impossible for the ASRD to affect the operation of the medical device. With this arrangement, upgrades to the ASRD can be made without the risk of adversely affecting the treatment delivered by the medical device. Also, only the medical device itself may be required to undergo the rigorous regulatory approval process to establish efficacy and safety whenever an upgrade is made.

[0006] The functions of the medical device and ASRD may be divided such that an operator may use the ASRD to figure out what is happening in the medical device and to monitor the progress of the medical procedure for which the medical device is being used. In order to modify the medical procedure being administered based on information obtained from the ASRD, the operator must adjust the controls of the medical device itself. Preferably, the medical device itself includes its own set of status indicators. Before adjusting the controls of the medical device, the operator can verify the state of these status indicators. These status indicators provide an additional level of safety, and reduce the chance that a medical procedure will be administered in an improper manner.

[0007] The requirement of an intervening operator is not the only dividing line between operations of the medical device and ASRD that may be employed. There is a risk that an ASRD that gives instructions for changing the settings of the medical device can cause errors to propagate into a treatment operation by way of an operator. Thus, the ASRD may be "isolated" using a more rigorous standard. The ASRD functions may defined as ones that are purely for relating non-critical system parameters that may not be used by an operator to make changes in the medical device's system settings. For example, the outputs of the ASRD may be restricted to non real-time output.

BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 is a block diagram of a system that includes a medical device and an auxiliary status reporting device.

[0009] FIG. 2 is block diagram of a control panel in which different types of controls and annunciator devices, which are isolated, are combined together to form a single control panel, but which are grouped separately.

[0010] FIG. 3 is a block diagram of a control panel in which different types of controls and annunciator devices, which are functionally isolated but otherwise integrated into a single control panel.

[0011] FIG. 4 is a block diagram of separate control panels, one for a treatment machine and one for an auxiliary monitoring device which are separately housed but which can be placed side-by-side for operational convenience . [0012] FIG. 5 is an illustration of a unitary treatment and monitoring device with separate control systems for treatment and pure monitoring functions illustrated by way of a digital control scheme.

[0013] FIG. 6 is an illustration of separate devices that encapsulate respective treatment-critical and treatment non-critical functions in separate housings and which are packaged and labeled separately.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0014] FIG. 1 depicts a system that includes a medical device 10 and an auxiliary status-reporting device (ASRD) 50. The medical device includes a set of controls 11 which are preferably implemented on a suitable control panel. These controls can be manipulated by the operator 30 in order to control the operation of the medical device 10. The medical device 10 also includes a set of status indicators 12 that provide feedback to the operator 30, and a patient interface subsystem 13. This subsystem 13 interfaces with the patient 20 in a manner that will depend on the medical procedure for which the medical device 10 was designed. For example, if the medical device 10 is a dialysis machine, the patient interface 13 may include appropriate components to receive blood from the patient, process the blood, and return the blood to the patient 20.

[0015] A controller 15 interacts with the controls 11, the status indicators 12, and the patient interface subsystem 13 in to ensure that the medical device 10 performs its intended function. The design of the controls 11, status indicators 12, patient interface subsystem 13 and the controller 15 may be in accord with the designs of various conventional medical devices known to persons skilled in the relevant art. Accordingly, details of the operation of the medical device 10 are not discussed herein. A distinction between the medical device 10 of the present invention and conventional medical devices is that the controller 15 is configured to output information that describes the status of the medical device 10 in detail. Preferably, the output information is extensive (or as close to exhaustive as possible) such that features may be added to the ASRD 50 without being hindered by insufficient information. This information is output to the world outside of the medical device 10 via the output interface 16. The ASRD 50 and medical device 10 may be co-located or even housed in a common housing 155.

[0016] It will usually be necessary to modify the components 11-15 (as compared to their conventional designs) so that complete information about the medical device 10 can be transmitted. For example, sensors ordinarily configured to provide status information directly to an observer may preferably include the ability to transmit multiplex information onto a data channel. Examples of status indicators 12 include lamps, LEDs, dials, rotating pointers, etc. Suitable modifications (e.g. adding buffers and data busses, optical rotation sensors, multiplexers, etc.) may be required to enable these status indicators 12 to report their status to the controller 15. Once the controller 15 obtains this status information, the controller 15 can report it via the output interface 16.

[0017] Examples of controls 11 include knobs, dials, and switches. These controls may also require modification so that the state of all of the controls on the medical device 10 can be ascertained by the controller 15. For example, if one of the controls was a dial that controls the speed on a pump, the position of that dial can be sensed using any conventional approach

(e.g., an optical sensor or a potentiometer) . Once the controller 15 ascertains the status of all the controls, the controller 15 can report that information via the output interface 16. [0018] Examples of the patient interface subsystem 13 include blood filters, high-voltage generators, and electrical impulse generators . These subsystems 13 may also require modifications so that complete information about the operation of the medical device 10 can be provided to the outside world.

[0019] Communication between the various subsystems 11-15 of the medical device 10 may be implemented using analog and/or digital electronics, in any conventional manner .

[0020] When the medical device 10 is being used to treat the patient 20, the operator 30 will control the medical device 10 via the controls 11, and monitor the status of the treatment via the status indicators 12. While treatment is being monitored in this manner by the operator 30, information about the status of the treatment and the medical device 10 is being transmitted out of the medical device 10 via the output interface 16.

[0021] The ASRD 50 has an input interface 56 that is designed to receive information that comes out of the medical device 10 via the output interface 16. The controller 55 accepts the information that arrives at the ASRD 50 via the input interface 56. The controller 55 is preferably implemented using a microcontroller or a microprocessor, but may also be implemented using discrete electronic components.

[0022] The controller 55 processes the information received via the input interface 56. Based on this information, the controller 55 can discern what is happening in the medical device 10. The controller 55 takes this information and analyzes it. The results of the analysis of this information are then reported to the operator 30 using the auxiliary status indicators 52. The auxiliary status indicators 52 are used to inform the operator 50 of the events that are occurring in the medical device 10. Examples of suitable hardware that can be used to serve as the auxiliary status indicators 52 include lamps, LEDs, rotating pointers, bar graphs, CRTs, and flat panel displays. Audio, vibration, radio, and other output devices may be employed as well. For example, stored speech commands may be output in response to an emergency situation guiding the operator or patient to take compensatory actions.

[0023] The controls 51 are used to accept commands from the operator 30. The operator 30 can select which information should be provided to him or her (via the status indicators 52) by operating the controls 51. In some embodiments, the operator can also select the format in which the information will be provided (e.g. bar graphs, line graphs, numeric displays, etc.) by operating the controls 51. The controller 55 recognizes when the controls 51 are being operated, and responds accordingly. [0024] For example, if the medical device 10 is a dialysis machine, the patient interface subsystem 13 might measure the blood pressure of the patient, the blood temperature, the red blood cell count of the patient, the volume of blood removed from the patient, and the volume of fluid returned to the patient. The controller 55 could be configured to display a history of the patient's blood pressure in response to a first command from the operator 30 received via the controls 51, and it could be programmed to display a history of the blood temperature in a graphical format based on the receipt of a second command from the operator 30 via the controls 51. Since the controller 55 has received information describing all the events occurring in the medical device 10 since the start of the procedure, the controller can provide the operator 30 with the desired information via the auxiliary status indicators 52. [0025] In one preferred embodiment, the auxiliary status device 50 is implemented in a computer running a standard operating system, such as Windows, Linux, or Unix. In such a case, the controls 51 might be a conventional keyboard and mouse, while the status indicators 52 could be a conventional CRT or flat-panel display. Conventional touch screens may also be used as a combination control/status indicator device. The interplay between the operator 30 and ASRD 50 may be implemented using any of a variety of well-known techniques for interfacing a computer with an operator. [0026] Optionally, the ASRD 50 may be configured to communicate with a remote device (e.g., via the internet, an extranet, a local area network, etc.) . When such a connection to a remote device is used, the remote device may be configured to access all of the information that was transmitted from the medical device 10 to the ASRD 50, and use that information for any desired purpose. The remote device can also be used to control the ASRD and even to upgrade the software that is being run on the ASRD 50.

[0027] Transfer of information from the medical device 10 to the ASRD 50 may be implemented using any conventional communication technique. Examples of suitable communication protocols include IRDA and Bluetooth. Preferably, the output interface 16 of the medical device 10 is configured so that no information from the ASRD can affect the operation of the medical device 10 (except indirectly by manual actuation of the controls 11 on the medical device 10 itself) . This may be accomplished, for example, by using a transmit-only interface device (e.g., an optical emitter or a radio frequency transmitter) in the medical device 10 without including a corresponding receiver. Another example is simply using opto-isolators in a wired communication channel .

[0028] According to an embodiment, a single control panel 200 integrates status indicators 12, auxiliary status indicators 52, control 11 and controls 51.

[0029] FIG. 2 is block diagram of a control panel in which different types of controls and annunciator devices, which are isolated, are combined together to form a single control panel, but which are grouped separately. The embodiment of FIG. 1 suggests that auxiliary status indicators 52, controls 51, status indicators 12 and controls 11 are housed in separate unitary devices, namely medical device 10 and ASRD 50. The functional isolation may be accomplished, however, by incorporating the functions of the auxiliary status indicators 52, controls 51, status indicators 12 and controls 11 into a single control panel or interface 200 as indicated in FIG. 2. These may be grouped separately in a single control panel as illustrated in FIG. 2, or they may be interspersed as illustrated in FIG. 3. FIG. 3 is a block diagram of a control panel 230 in which different types of controls and annunciator devices including display 220 and control 210 components are functionally isolated but otherwise integrated into a single control panel 230.

[0030] FIG. 4 is a block diagram of separate control panels 232A and 232B, one for a treatment machine 230A and one for a ASRD 230B. Each control panel as a respective one or more displays 220A/220B and a respective one or more controls 210A/210B. Each also has a separate respective housing, a first housing 231A for the treatment device 230A and a second housing 230B for the ASRD 230B. The treatment machine 230A and the ASRD 230B may be configured as separate unitary devices which may be located side-by-side connected by a communications interface 229.

[0031] FIG. 5 is an illustration of a unitary treatment and monitoring device 340 with separate control systems 301A and 30IB for treatment (301A) and monitoring (301B) functions. The treatment control system 301A includes a programmable processor 305 that runs software stored in memory 300 controlling output and responding to inputs through a user interface 310. The treatment control system 301A processor 305 also controls treatment actuators and sensors 315. The monitoring control system 301B includes a programmable processor 3330 that runs software stored in memory 350 controlling output and responding to inputs through a user interface 335. Respective I/O interfaces, one 320 for the treatment control system 301A and one 325 for the monitoring system are linked to convey information between the two. [0032] The functions performed by the monitoring system 30IB may enhance functions already performed by the treatment system 301A. The latter may already output sensor data or error conditions in a certain format. However, the same data may be output in an enhanced format by the monitoring system 301B. For example, the treatment system 301A may output instantaneous pressure of a portion of a blood circuit in a numerical display , forming part of the user interface 310. The monitoring system 30IB may enhance this data by storing a time- series of pressure signals and displaying through user interface 335 a time-graph of the time series of pressure signals. Another example is where the monitoring system 301B outputs a graphical representation of the instantaneous pressure signal with high and low limits indicated as a bar graph (not illustrated) with upper and lower bounds represented as lines to give a more easily understood representation of the current pressure signal. Another example is that the monitoring system 30IB may be employed to translate cryptic error codes into verbose format with instructions for trouble-shooting. Yet another example is during set-up of the system, an online user manual stored in memory 350 may be output by the user interface 335 and controlled according to signals from the treatment system 301A. Yet another example is that the monitoring system 30IB may translate the language of data from the treatment system 301A. [0033] FIG. 6 is an illustration of separate devices treatment 405A and monitoring 405B devices that encapsulate respective treatment-critical and treatment non-critical functions in separate housings. They are packaged in separate containers 410A and 410B with separate labels 430A and 430B to give an indication to users that one is a monitoring only device and one is a medical treatment device which may be treated differently by, for example, a hospital's regulations..

Claims

1. A medical treatment device comprising: a treatment unit and a monitor unit positioned together at a treatment location; said treatment unit including components that deliver medical treatment to a patient; said monitor unit being signally connected to said treatment unit by means of a one-way communication mechanism such that said monitor unit are prevented from affecting the state of said treatment unit; said monitor unit receiving data from said treatment unit and outputting at least data relating to a status of a treatment being delivered by said treatment unit .

2. A device as in claim 1, wherein said treatment unit and said monitor unit are housed together in a single housing.

3. A device as in claim 1, wherein said treatment unit and said monitor are connected to a common control panel with inputs and outputs, each connected such that any signals from said monitor unit are prevented from affecting a state of said treatment unit.

4. A device as in claim 3, wherein said treatment unit and said monitor unit and said control panel are located within a common housing.

5. A device as in claim 3, wherein said control panel comprises physically separate components that are connected by a one-way communications channel.

6. A medical treatment device, comprising: a treatment machine with sensors and actuators configured to multiplex status information; a monitor device having a programmable processor with a memory, said processor being configured to control functions, including data synthesis and display, of said monitor device responsively to software run by said programmable processor; a one-way communications channel providing communications between said treatment machine and said monitor device, such that said treatment machine status is prevented from being affected by said software; said treatment machine sensors and actuators being configured to apply data signals to said one-way communications channel, said processor being configured to control said functions responsively to said data signals .

7. A device as in claim 6, wherein said treatment machine and monitor device share a common housing.

8. A device as in claim 6, wherein said one-way communications channel is wireless.

9. A medical treatment device, comprising: a blood treatment unit; a monitoring control and display device; a control computer controlling said blood treatment unit; a monitoring computer controlling said monitoring control and display device; said monitoring computer signally connected to said blood treatment unit such that failures in said monitoring computer cannot affect the state of said control computer.

10. A device as in claim 9, wherein said monitoring computer translates status information from said control computer and displays a translated result on said monitoring.