Blood letting apparatus

1 BLOOD LETTING APPARATUS

BACKGROUND OF THE INVENTION

l. Field of the Invention

The present invention resides in the field of a medical apparatus, and more particularly to a blood letting apparatus adapted for self-administration.

Some medical conditions, by way of example diabetes, require that the patient be tested for blood content, and particularly blood sugar content. In the case of a diabetic patient, at the early stages of insulin therapy it is necessary, in order to determine the proper insulin dosages, that blood samples be tested many times a day.

Numerous systems for patient self-monitoring of blood glucose levels have been developed. However, in each such system it is necessary for the patient or for an attendant to draw blood.

2. The Prior Art

Numerous devices have been employed for the drawing of the small quantities of blood necessary for effecting blood glucose level testing.

In my U.S. Pat. Nos. 2,801,633 and 3,046,987 there are disclosed various forms of an improved lancet member which enable the drawing of blood samples with minimal trauma to the patient and minimal admixture of tissue fluids, which latter tend prematurely to coagulate the blood and by admixing with the blood to give misleading or inaccurate readings.

The procedure of self blood letting by stabbing with a lancet or like piercing instrument, even using the improved lancets described in my above mentioned patents, presents a difficult task to the patient. There is a natural tendency for the patient to flinch, with the result that the desired clean wound will not be produced or that the lancet will not enter the skin in a perpendicular orientation. In addition, it is not unusual for an inexperienced patient to fail to insert the lancet through the dermal layers, with the result that the procedure must be repeated.

In order to minimize the manipulative procedures involved in a self-stabbing procedure, mechanical devices have been constructed which perform the stabbing task. Such devices typically employ a spring biased plunger which carries a sharpened end. The devices are used by cocking the plunger and positioning the distal portion of the device against the skin to be pierced, following which the plunger is released. The plunger will carry the lancet tip to a preset depth into the tissue of the patient.

The use of the devices of the type described has been found to be painful and to induce substantial trauma in the areas surrounding the puncture. It has been theorized that the trauma and pain are engendered in large measure by the speed at which the lancet is travelling when the wound is effected.

SUMMARY OF THE INVENTION

The present invention may be summarized as directed to a novel blood letting device which is characterized by simplicity of operation, assurance of sterility, predictability of depth of penetration, reduced trauma in surrounding tissues and, above all, minimization of pain sensation.

The apparatus includes a guide member within which is movably mounted a lancet carrier adapted to receive a sterile, disposable lancet. A hammer member is shiftable between cocked and fired positions. An important

2

feature of the invention resides in the fact that the lancet carrier and hammer are independently movable.

In use, a lancet affixed in the carrier is positioned with its point resting on the surface of the skin, usually of a finger tip. The patient will thus perceive a slight pressure sensation from the point of the lancet itself. When the hammer is released from the cocked to the fired position, it strikes the carrier, whereby the cutting point of the lancet is forced into the tissue to a precisely predetermined depth.

It has unexpectedly been discovered that the sensation of pain is substantially lessened where there is initial contact between the lancet tip and the skin than is the case in conventional mechanical blood letting devices where the lancet point is brought from a position clear of the skin into forceable contact with and penetration of the skin.

It has further been found that the trauma produced by the described apparatus is substantially less than that experienced with manually or mechanically operated lancets heretofore known.

It is accordingly an object of the present invention to provide a blood letting device particularly adapted for self administration but, of course, also useful professionally, which is characterized by the assured provision of a clean and relatively painless wound, yielding blood samples containing a minimum of tissue fluids.

A further object of the invention is the provision of a device of the type described wherein a pouting or distending influence is exerted on the skin by the instrument, encouraging a free flow of blood.

Still a further object of the invention is the provision of a blood letting device of the type described having a mechanical hammer and a lancet carrier and wherein the carrier is independent of the hammer, whereby an initial pressure of the lancet against the skin is effected prior to release of the hammer, which sequence has been found greatly to reduce the pain factor in the blood letting process.

Still a further object of the invention is the provision

of a device of the type described which is particularly»

well adapted to the use of lancets as disclosed in my U.S. Pat. Nos. 2,801,633 and 3,046,987.

To attain these objects and such further objects as may appear herein or be hereinafter pointed out, reference is made to the accompanying drawings forming a part hereof, in which:

FIG. 1 is a perspective view of a representative example of apparatus of the type described in the lancet loading position thereof;

FIG. 2 is a magnified vertical section taken on the line 2—2 of FIG. 1; .

FIG. 3 is a further magnified horizontal section taken on the line 3—3 of FIG. 2;

FIGS. 4 and 5 are vertical sections similar to FIG. 2 showing the position of the parts, respectively in the prefired and fired positions thereof.

Referring now to the drawings, there is shown a blood letting instrument 10 which is comprised of a body portion or guide member 11, illustratively in the form of a hollow tube having an axially extending interior bore 12. Within the bore 12 and adjacent the bottom end 13 of the guide member 11 there is mounted an axially moveable lancet carrier member 14.

The carrier member 14 which, as seen in FIG. 3, is cylindrical in transverse section, includes an end portion 15 which is positioned to engage against a stop