US3179106A

US3179106A - Method and apparatus for preventing venous blood clotting

Info

Publication number: US3179106A
Application number: US224301A
Authority: US
Inventors: Paul A Meredith
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-09-18
Filing date: 1962-09-18
Publication date: 1965-04-20
Anticipated expiration: 1982-04-20
Also published as: GB1010243A

Description

April 20, 1965 P. A. MEREDITH 3,179,106

METHOD AND APPARATUS FOR PREVENTING VENOUS BLUOD CLOTTING Filed Sept. 18, 1962 Q S 3 a o N .l E F. \\....35 t \9 I%IIII n W 7 5 INVENTOR: PAUL A. MEREDITH Wei ATT'Ys United States Patent laul A. Meredith, 94d North East Ave, Gals Park, llh

Filed Sept. 1S, 1962, Ser. No. 224,301 llClairns. (Qi. lid-=24) This invention relates to a method and apparatus for preventing phlebothrombosis in the extremities andabdomen; more particularly, it involves the elimination of venous stasis in these body areas.

A primary cause of phlebothrombosis is venous stasis, typically resulting from inactivity, as with bed-ridden patients, or chronic circulatory ailments. Phlebothrombosis is a particularly dangerous condition in that the phlebothrombi often break up into emboli which lodge in the lung, as they move toward the central portion of the circulatory system. It is desirable to prevent phelbothrombosis as the consequent risk of pulmonary embolism is substantially reduced. Thus, the principal object of this invention is to obtain a method for the prevention of phlebothrombosis in the extremities and abdomen.

Another object of the invention is to provide a method of the character described that will not interfere with normal circulation.

It is also an object to provide a device for preventing the formation of phlebothrombi.

Yet another object is to provide a device of the charac ter described that will operate independently of patient cooperation.

Other objects and advantages of the invention will be apparent from the following description in conjunction with the accompanying drawing in which:

FIGURE 1 illustrates a preferred embodiment of the invention;

FIGURE 2 illustrates diagrammatically a mechanism for intermittently producing pulses of minimal pressure in practicing the embodiment of FlGURE l; and

FIGURE 3 illustrates graphically the relationship between time and pressure according to one method of practicing the invention.

With these objects in view and other objects that will appear as the description proceeds, the method, broadly described, involves the removal of static venous blood by intermittent application of minimal external pressure. The essence ofthe invention resides in to use of rapid pulses of minimal pressure over prescribed intervals. In the normal individual the. venous blood pressure is ap proximately 10 millimeters of mercury (mm. Hg). In this novel method, intermittent application ofrapid pulses of external pressure of about this magnitude is sufficient to empty static blood from the veins of the arms and legs.

Similarly, external pressure, applied intermittently in rapid pulses of the same approximate magnitude, will prevent stasis of blood in the abdominal veins. The great advantage of this method is that rapid pulses of a minimal pressure do not interfere with circulation in the arterioles and capillaries, where the blood is under relatively higher pressure. This pulse of minimal pressure is strong enough to push the blood out of the vein, yet it is not so strong as to inhibit normal circulation. Due to the short duration of the pulse, the veins rapidly open to permit influx of blood from more distant parts of the circulatory system.

The pulse of minimal pressure is applied over a short period of time, from one-tenth to one second. In preferred form, the pulse has a duration of about one-half second. After the pulse is applied, there follows a relatively longer idle period during which no pressure is applied. This idle period is typically from 10 to 300 times the duration of the pulse of pressure. In the case of the preferred duration of the pulse of one-half second, the idle period would last from 5 to 150 seconds. Varying "ice circumstances may make it necessary to apply the pressure pulse more or less often.

The magnitude of the pulse of pressure is quite small, barely being perceptible to the patient. Typically, the pulse pressure is between 5 and 15 mm. of Hg, being just suiiicient to overcome the normal venous blood pressure toempty the vein. In special cases, for example, with patients having abnormally high venous blood pressures, the pulse'pressure may, of necessity, be as high as 30 mm. Hg.

The method of intermittently applying the rapid pulses of minimal pressure is equally effective in eliminating venous stasis in the extremities and in the abdomen. Thus, the pulses of minimal pressure, over the appropriate cycle,

ray be applied to any of the following parts of the body, as the individual case demands: forearms, upperarms, calves, thighs and abdomen.

in a preferred embodiment of the invention, pulses of minimal pressure are applied in rapid sequence to different portions of the body. As an example, a first pulse of minimal pressure to the calves and forearms, a second pulse to the thighs and upperarms; and a third pulse to the abdomen. Following this there is the usual relatively longer period during which no pres no is exerted. This enrodiment of the method has the added advantage of systematically encouragingthe venous circulation in addi tion to the elimination of venous stasis and prevention of phlebothrombosis.

This invention also provides a device for eficctuating the novel method of preventing phlebothrombosis hereinefore described. In its most basic form, the device consists of pressure applying means, means for intermittently producing pulses of minimal pressure, connecting means for conveying the pulse of minimal pressure from the pressure producing means to the pressure applying means, and means for controlling the cycle of pulses and magnitude of the minimal pressure.

in preferred form the device provides a series of pressure applying means whereby the pulses of minimal pressure can be applied in rapid sequence to different areas of the body. The series of pressure applying means may be used in conjunction with a common pressure producing device, in which case distribution means must be provided whereby the pressure applying means will receive the pulses of minimal pressure selectively sequentially. Alternatively, each separate pressure applying means, or con.- bination thereof may be provided with its own pressure producing means. Control means are provided, in either embodiment whereby the duration, cycle and magnitude of the sequence of pulses of minimal pressure are regulated to conform to the individual patients needs.

The drawings illustrate one possible embodiment of this invention. FIG. 1 shows this embodiment used on a bedridden patient. Referring to the numbers,

inflatable bladders

1 and 2, fashioned to fit the calves, and 3 and 4, fashioned to fit the forearms are connected via hoses 5, 6, 7' and 8 and via connecting T 9 to a compression chamber 1t (FIG. 2) within box 11. Similarly,

inflatable bladders

12 and 31, fashioned to fit the thighs, and 14 and 15, fashioned to fit the upper arms, are connected via hoses id, 17, 18 and 19 and via connecting T it) to a compression means 21 within box ll. Hoses 5, d, '7 and 8 should be of relatively large cross section as the pressure increment is small. Inflatable bladder 2, fashioned to fitthe abdomen is connected via hose 23 and outlet 24 to a compression means 25 within box ll. The box 11 contains, in addition to compression means

1t

21 and 25, cycle controlling means 26, pressure regulating means 2'7 and gauges 28, 2s.

,FIUTJRE 2 shows schematically the interior to the box 11 of FIG. 1. Motor 3t? controlled byspeed control A is connected through drive wheel 31 to shaft 32 via connecting rod 33. n shaft 32 are a series of

cams

36, 37, 3% adjustable for timing and displacement by adjusting

screws

36A, 37A and 38A. Compression means 10, 21 and 25 are formed of large cylinders 39, 40, 41 and diaphragms 42, 43, 44. Connecting

tubes

48 and 49 lead to connecting Ts 9 and 20 and connecting tube 59 leads to outlet 24. Diaphragm rods 51, 52 and 53 press against shaft 32 and earns 36, 37 and 33. Slide guides 34 control the path of movement of shaft 32 and rods 51, 52, and

53. Not shown is a cam lifting mechanism at 34 to lift the cam rod 32 off of the cam followers 51, 52 and 53 on the return stroke of the rod 52. Springs 35 restore diaphragms 42, 43 and 44 to their initial positions. Pressure equalizing

valves

54, 55 and e are provided for each of the cylinders 39, 40 and 41 to restore the initial air pressure to atmospheric after each actuation of the respective diaphragms. For this purpose flipper valves or other self-equalizing valves can be used. In the absence of a pressure equalizing system, uniform action would not be obtained due to leakage of air which occurs to some extent in any closed system.

The operation of the device proceeds as follows: the motor 30 via drive wheel 31 and connecting rod 33 imparts reciprocating motion to shaft 32. Cams 36, 37 and 38 sequentially activate diaphragms 42, 43 and 44 via diaphragm rods 51, 52 and 53. The diaphragm strokes, controlled by the size and shape of the cams, are short and the movement of the diaphragms changes only slightly the volume of the cylinder. The minimal pressure, se-

quentially produced in the cylinders 39, 4t and 41 is conveyed via

tubes

48, 49 and 50, via connecting Ts 9 and 2t) and outlet 24 and via

hoses

5, 6, 7, 8, 116, 17 18, 19 and 23 to inflatable bladers, ll, 2, 3, 4, 12, 13, 14, and 22. The initial order is A, B, C, i.e., lower legs, lower arms (A), upper legs, upper arms (B) and abdomen (C). The diaphragm compression cylinders are of such size that the diaphragm strokes will cause only a small reduction in the total volume of the system (i.e., cylinder plus bladders) and will produce a minimal superatmospheric pressure of about 5 to 15 millimeters of mercury in the system.

FIG. 3 is a graphical depiction of the sequence of pulses produced by the embodiment of FIGS. 1 and 2. It is a plot of pressure, in mm. Hg versus time. Curve 57 shows the pressure-time relationship characteristic of compression means It), curves 58 and E9 show similar relationships for compression means 21 and which are activated sequentially thereafter.

There is next a relatively longer period of time during which no pressure is exerted, whereupon the cycle of three sequentially produced pulses is repeated (curves 60, 61 and 62).

While one preferred embodiment of the device is shown, it is obvious that many changes can be made without departing from the spirit of the invention. The number of sequential cycles can be varied, for example, from one to ten.

The pressure cylinders are preferably capable of holding rather large volumes of fluid such as air, e.g., 25 liters, and the reduction of volume is preferably minor, e.g., 5% or less, as compared to the total volume of the cylinders.

The inflatable bladders are made of rubber or any other expandable, inflatable material which can, if desired, be covered with cloth. These bladders are generally similar in construction to those used by the medical profession for application to the arms for blood pressure determinations.

The invention is hereby claimed as follows:

1. The method for preventing blood clot formation in the veins of the extremities and abdomen which comprises intermittently'emptying the blood from said veins by the application of minimal external pressure to said body member just suflicient to overcome the normal venous blood pressure and to empty the veins, said minimal pressure being at least about 5 millimeters of mercury and not 4 exceeding about 30 millimeters of mercury and being exerted in rapid pulses and said pulses being followed by a relatively longer idle period during which no pressure is exerted.

2. The method for preventing blood clot formation in the veins of the extremities and abdomen which comprises intermittently emptying the blood from said veins by the application of minimal external pressure of about 5 to 15 millimeters of mercury to said body members, said minimal pressure being exerted in rapid pulses, said pulses being followed by a relatively longer idle period during which no pressure is exerted.

3. The method for preventing blood clot formation in the veins of the extremities and abdomen which comprises intermittently emptying the blood from said veins by the application of minimal external pressure to said body members, said minimal pressure being exerted in a sequence of rapid pulses not exceeding about one second in duration, said sequence of pulses being followed by a relatively longer idle period during which no pressure is exerted, the magnitude of said minimal pressure being about 5-15 millimeters of mercury.

4. The method for preventing blood clot formation in the veins of the extremities and abdomen which comprises intermittently emptying the blood from said veins by the application of minimal external pressure of about 5 to 15 millimeters of mercury to said body members, said minimal pressure being applied in a sequence of rapid pulses, said pulses being followed by a relatively longer idle period during which no pressure is exerted, each of the pulses of said sequence lasting about one-half second and said idle period lasting from about 5 to seconds.

5. The method for preventing blood clot formation in the veins of the extremities and abdomen which comprises intermittently emptying the blood from said veins by the application of minimal external pressure to said body members, said minimal pressure being applied in a sequence of three rapid pulses, the first pulse being applied to the calves and forearms, the second to the thigh and upperarms, and the third to the abdomen, said sequence of three pulses being followed by a relatively longer idle period during which no pressure is exerted, said minimal pressure being about 5-15 millimeters of mercury, said sequence of pulses lasting no longer than about three seconds and said idle period lasting from about 10 to 300 times longer than said sequence of pulses.

6. An apparatus for preventing blood clot formation in the veins of the extremities and abdomen comprising means for applying pulses of minimal pressure to the extremities and abdomen, means for producing said pulses of minimal pressure of at least about 5 millimeters of mercury and not exceeding about 30 millimeters of mercury, means for connecting said applying means and said producing means, means for controlling the magnitude of the minimal pressure developed in said pressure producing means and means for regulating the operation cycle of said producing and said applying means whereby each of said pulses of minimal pressure is produced and applied rapidly followed by a relatively longer idle period during which no pressure is exerted.

7. An apparatus for preventing blood clot formation in the veins of the extremities and abdomen comprising means for applying pulses of minimal pressure to the extremities and abdomen, means for producing pulses of minimal pressure of about 5 to 15 millimeters of mercury, means for connecting said applying means and said producing means, means for regulating the magnitude of the minimal pressure produced and means for regulating the operation cycle of said applying means and said producing means whereby said pulses of minimal pressure are produced and applied rapidly followed by a relatively longer idle period during which no pressure is exerted and whereby a pulse of said minimal pressure lasts no longer than about 1 second and said idle period lasts from about 5 to about 150 seconds.

8. An apparatus for preventing blood clot formation in the veins of the extremities and abdomen comprising a series of means for applying rapid pulses of minimal pressure to the extremities and abdomen, means for producing said pulses of minimal pressure, the magnitude of said pulses being about 5-15 millimeters of mercury, means for regulating the magnitude of the minimal pressure produced, means for distributing said pulses of minimal pressure whereby said series of applying means sequentially receive said pulses of minimal pressure, each one of said pulses lasting no longer than about 1 second, and whereby the sequential distribution of said pulses is followed by a relatively longer idle period during which no pressure is exerted, said idle period lasting from about to 300 times longer than one of said rapid pulses.

9. An apparatus for preventing blood clot formation in the veins of the extremities and abdomen comprising a series of similarly constructed pressure systems each comprising means for applying rapid pulses of minimal pressure to the extremities and abdomen, means for producing said pulses, the magnitude of said pulses being at least about 5 millimeters and not exceeding about 30 millimeters of mercury, means for connecting said producing means and said applying means, means for regulating the magnitude of said pulses, means for regulating the operation cycle of said series of pressure systems whereby said pulses are rapidly and sequentially produced and applied followed by a relatively longer idle period during which no pressure is exerted.

10. An apparatus for preventing blood clot formation in the veins of the extremities and abdomen comprising a series of similar pressure systems each comprising inflatable bladders adapted to fit a body member, each systern comprising a diaphragm type compression cylinder of such sizethat the diaphragm stroke will cause only a small reduction in the total volume of the cylinder and bladders and will produce a minimal superatmospheric pressure at least about 5 millimeters and not exceeding about 30 millimeters of mercury in the system, said cylinder being provided with an equalization valve suitable for returning the system to atmospheric pressure after said diaphragm stroke is completed; hoses connecting said cylinder and said bladders; a cam connected to activate the diaphragm of each of said systems; motor means driving said cams; means for regulating the magnitude of the pulses of minimal pressure produced in said systems; and means for regulating the operation cycle of said systerns whereby said series of systems is activated rapidly and sequentially by said motor driven cam followed by a relatively longer idle period during which no pressure is produced or applied.

11. The apparatus of claim 10 wherein. there are three of said pressure systems, the first having four of said bladders, two adapted to fit the calf and two adapted to fit the forearms, the second of said systems having four of said bladders, two adapted to fit the thigh and two adapted to fit the upper arms, and the third of said systems having one said bladder adapted to fit the abdomen.

References Cited in the file of this patent UNITED STATES PATENTS 2,361,242 Rosett Oct. 24, 1944 2,959,171 Seligman NOV. 8, 1960 RICHARD A. GAUDET, Primary Examiner. RICHARD. J. HOFFMAN, Examiner.

Claims

1. THE METHOD FOR PREVENTING BLOOD CLOT FORMATION IN THE VEINS OF THE EXTREMITIES AND ABDOMEN WHICH COMPRISES INTERMITTENTLY OF MINIMAL EXTERNAL PRESSURE TO SAID BODY APPLICATION OF MINIMAL EXTERNAL PRESSURE TO SAID BODY MEMBER JUST SUFFICIENT TO OVERCOME THE NORMAL VENOUS BLOOD PRESSURE AND TO EMPTY THE VEINS, SAID MINIMAL PRESSURE BEING AT LEAST ABOUT 5 MILLIMETERS OF MERCURY AND BEING EXCEEDING ABOUT 30 MILLIMETERS OF MERCURY AND BEING EXERTED IN RAPID PULSES AND SAID PULSES BEING FOLLOWED BY A RELATIVELY LONGER IDLE PERIOD DURING WHICH NO PRESSURE IS EXERTED.