JPS595302B2 - External pressure circulation support device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an external pressure circulatory assist device of the type that uses an electrocardiogram to facilitate synchronization of heart beats and pressure pulses.

Atraumatic methods of helping blood circulation in patients are already known in the art.

According to Tennis, US Pat. No. 3,303,841, applying external pressure to the lower part of the body squeezes out more blood than is pumped by the heart in one heartbeat.

This squeezed blood is forced back into the aorta and the larger ductus arteriosus, thereby reducing the strain on the ventricles while maintaining good blood filling during ventricular expansion.

This general process is detailed in the ``Synchronized Circulatory Support Technique'' by Birdwell et al., published in the Journal of the Canadian Medical Association, September 24, 1966 (Vol. 95, pp. 652-664). .

In general, the synchronous external pressure assistance method is clearer and superior to the existing contralateral pressure assistance method.

The reason is that in the latter case, cannulation of the aorta,
Problems include the use of special bodily blood processing equipment, the use of less useful techniques, and the need to provide anticoagulants to the patient.

Furthermore, the bleeding trauma and hemolysis created by special body pump devices limits the allowable assistance time and worsens the patient's condition.

Finally, such traumatic methods are not only time consuming, but can pose a very serious risk to many patients, increasing the risk factor when treating all patients.

Accordingly, one object of the present invention is to provide an improved external pressure circulatory aid device that is easily and safely applied and used by hospital personnel of ordinary skill and those unfamiliar with such devices. be.

The above objects have been achieved by creating an external pressure circulation assist device having one or more of the following advanced technologies.

N. Water Filling Device A water filling device is used to fill a bag surrounding the foot with an amount of water appropriate for a particular patient.

A suitable amount refers to a specific amount appropriate to the size and shape of the individual patient's foot.

It has also been determined that the patient's foot may change its effective size during processing due to patient movement in and out of the machine.

In other words, the water filling device does not just fill water appropriately;
It is also used to automatically drain water from the bags that surround the feet.

It is also used to dose or subtract water during the procedure, thereby maintaining an effective hydraulic connection between the mechanical pressure inducing device described below and the patient's foot.

During a filling operation, a pressure sensor placed between the shell surrounding the bag and the bag itself detects the pressure within the bag.

When the filling pressure reaches a sufficient level (usually about 25 WHg), the filling operation is terminated by stopping the filling pump.

This filling is usually accomplished by a reciprocating member in an upper position, ie, in a position compressing the bag.

Once operation of the device begins, a displacement detector regulated by the reciprocating member positions the reciprocating member at the top of each upward stroke.

If this position is incorrect, water is pumped into and out of the bag until the reciprocating member is again in the correct position.

B1 Mechanical pressurization device In order to obtain an appropriate pair of pulsations, the bag surrounding the foot applies positive pressure to the foot during cardiac diffusion, removes that pressure during cardiac contraction, or applies negative pressure to the foot (for example -50vrm). It must be possible to create Hg).

The amount of positive pressure that can be generated is approximately 150 to 250 at all times.
It is 711 mHg.

Most conveniently, this pressure differential is achieved by applying the reciprocating member to a fairly large surface of the tabi containing liquid.

This reciprocating member is mounted under the tabi for reciprocating vertical movement that adjusts the amount of positive pressure.

The pressure in the bag increases as the reciprocating member rises relative to it and decreases to a minimum (typically 25MHg) as the reciprocating member descends to a lower level (or if negative pressure is used). ).

If the negative pressure capabilities of the present invention are used, the reciprocating member, the bag and the patient's body are encased from the waist down in a bag that is partially evacuated to a negative pressure of, for example, 70 WHg below atmospheric pressure. It will be done.

The bag is preferably of Frenizipur material and is held away from the foot by the rest of the device so that a low pressure zone of negative pressure is maintained.

The bag or suction bladder is snugly fitted to the patient's body with a waistband and sealed appropriately at the waist.

The above-mentioned device is -50Ill;Ill Hg-+250
It has a normal operating cycle in the MHg range.

In operation, the pressure is cycled with lower pressures of the cycle coinciding with the systolic aspect of the heart's work and higher pressures coinciding with the heart's diastole.

Tabi, which are convenient single-chambered blankets, are placed around the patient's feet, and rigid gauging is used to wrap the legs and the edges of the mechanical pressure transmitting reciprocating member.

The bladder is then filled with water until it is filled all around the foot and over the reciprocating member, such that the bladder is in contact with substantially the entire surface of the foot and is fully inflated at the ankle and hip ends. Ru.

In this regard, vertical reciprocating motion of the reciprocating member provides the desired normal operating cycle.

7. Pressure waveform control device: In order to obtain pulsation, the pressure applied to the patient's foot must be varied according to the desired waveform.

The device of the present invention has advantageous features whereby foot pressure is monitored and a feedback signal source is created which is directly compared to a signal representative of the waveform required for a particular patient.

The difference between the signal obtained from the actual waveform and the signal representing the desired waveform is called the "error signal."

This error signal is amplified and used to adjust an electric servo valve that regulates the flow of hydraulic fluid in a hydraulic cylinder that drives a vertically reciprocating platen.

This flow is constantly adjusted in proportion to the error signal so that the transducer pressure waveform more closely resembles the desired waveform.

Foot pressure monitoring is approximately 10cxx 10crrLX 1.
This is conveniently carried out by a water bladder of dimensions A71 in 2, which is placed between the shell surrounding the bladder and the bladder itself.

The water in this sensing bag is connected through a short tube to a pressure quadrature transducer that produces the required electrical signal of the actual pressure waveform.

One advantage of this waveform control device is that it ensures that important characteristics of the desired waveform (e.g. duration, rise time, and fall time) are not compromised when applied to a patient's foot. .

This is despite variations in the hydraulic coupling between the reciprocating member and the foot caused by different patient-to-patient foot contours, sizes, and stiffnesses, and also due to deformation of the foot casing and dynamic stretching of the bladder during movement. achieved regardless.

Cardiac and pressure cycle phasing It has been found that when the heart experiences inappropriate timing of the onset of externally assisted pressure waves with respect to its beating cycle, deleterious physiological effects occur.

Furthermore, although this phenomenon is easily understood by the user, it is desirable for the user to avoid mistakes and to simplify the operation of the device by using a simple and accurate automatic phasing device.

In the present invention, a suitable visually monitored phasing control device is provided,
The arterial waveform is thereby displayed along with the EKG waveform on a multi-channel oscilloscope or other suitable display device.

Arterial pressure waveforms are measured at any convenient location in the body.

Typically, the most convenient location for an arterial wave pressure sensing device is the wrist.

EKG signals are often obtained by a detector placed directly on the torso near the heart.

In this application, it is important to know that the pressure waves introduced into the thigh artery by the device of the invention take approximately 80 m5 to reach the root of the aorta.

Continuous transmission from the root of the aorta, where the arterial waveform is obtained as a standard, to the wrist takes another 90 m5.

Importantly, an artificially induced positive pressure wave is created in the legs well before cardiac dilation, and that the pressure wave reaches the root of the aorta at the onset of cardiac diastole.

Therefore, the onset of the enhanced diastolic waveform seen at the wrist resulting from use of the device occurs a total of 170 m5 after pressure is applied to the patient's feet.

That is, in the illustrative situation, 170 m5 before the arterial waves, such as those seen at the wrist, indicate the onset of cardiac diastole.
Also, 80m before EKGfg indicated the start of cardiac expansion.
It is desirable to have the induced pressure wave initiated by a command signal that is timed to begin before 5 pm.

The onset of cardiac diastole is marked in the arterial wave by the so-called diastole, which is analogous to the relaxation of the left ventricle and the end of the so-called "T wave", which is known to clearly mark the end of cardiac contraction.

In this phasing device, the foot pressurization signal is used to intensify the E K G, and the arterial traces appearing on the oscilloscope 7' after this pressurization are displayed for 80 m5 and 170 m5, respectively.

This device allows the user to adjust the delay time until the E K G or arterial waveform enhancement signal is placed at the onset of cardiac diastole.

In that regard, foot pressurization can be triggered in proper synchronization with the cardiac cycle.

It has been found particularly desirable to have a synchronizer that is highly versatile, i.e., that is not subject to the expected constant delay between events in the aorta and events previously detected at the detection location.

This is done by adjusting the synchronization of the controller and the external circulatory aid device, thereby reducing the time difference between an aortic event (usually the E K 0 curve "R" wave) and the triggering of the circulatory aid pressure. The optimal time is the visual type that is moved during the setting of the time variable through a time range that compensates for the time difference between the aortic phenomenon and its expression at any arterial wave sensing location selected during the procedure. Accurately obtained by mobile pointing device.

Visual markers are conveniently electronic, and markers can be used as tracing enhancements on finger plethysmography, or similar cardiac As an indication of the phenomenon, it is moved along the channels of the oscilloscope.

91 Foot Wrapping Unit A new foot wrapping unit is used whose light weight and profile provide an effective casing for pressurizing the foot, yet can be conveniently and quickly applied to the patient.

E. Reciprocating Member Drive Mechanism A new mechanical linkage is provided to couple the reciprocating member to the drive hydraulic cylinder, thereby providing suitable pressure displacement characteristics on the reciprocating member for pressurizing the bag, while A desirable dissipation of stress and improved control of the pulsation cycle is obtained, especially when the location is operated at sub-baric pressures.

1 and 2, the leg 20 is filled with an incompressible liquid such as water 23.
It is placed in a blanket-like bag 22 filled with water.

The bladder 22 completely encloses the foot 20 and is a slip fit within a durable casing 24 comprised of a single upper foot casing member or shell 26 and a single lower foot casing member or shell 28.

Immediately below the bag 22, a reciprocating member 30, also within the casing 24, is mounted for reciprocating vertical motion conveyed by a mechanical linkage 32.

This linkage is driven by a hydraulic cylinder, as best seen in Figure 5C.

Reciprocating member 30 and mechanical linkage 32 constitute a mechanical displacement device.

Pressure sensitive transducer (detector) 34 (4th A
(see figure) is placed in the hydraulic passageway to the bag and is used to monitor the pressure inside it.

The special features of this transsteer will be explained below.

FIG. 2 shows a method of wrapping the enclosure 36fJ3 casing 24.

Envelope 36 and casing 24 are tongued to indicate the relative position of reciprocating member 30.

The enclosure extends beyond the casing 24 and extends around the waist 3 of the patient 40.
8, it will be seen that it is adapted to be a slip fit.

The suction pump 39 is constantly used to maintain a normal environment inside the enclosure 36 at atmospheric pressure.

There are some cyclic fading problems that are solved by the use of the present invention.

If pressure is applied to the patient's leg from above the bag 22, such pressure will reach the heart and cause the E K placed on the patient's chest to reach the heart.
It should normally take about 80 milliseconds (ms) to synchronize with the heartbeat as monitored by the G@ device.

It takes another 90 m5 to reach the radial artery, where the influence of the pressure starting in the foot is monitored by a detection device placed above it.

FIG. 3 is a diagram showing a graph of time phenomena related to the operation of the device.

One trace shows the real-time E K 0 curve for a normal cardiac cycle of 840 m5.

In this trace, the beginning of cardiac diastole is typically represented by the beginning of the curve's descent at 403.

This drop at 403 corresponds to the rise 40 of the foot pressure curve 404.
5 It shall last approximately 80m5.

This is so that the pressure waves induced by the device of the invention reach the heart after an 80 second trip, at the onset of cardiac diastole.

Curve 407 is the curve of radial artery pressure measured at the lumbar region.

The onset of diastole in pressure curve 407 is represented by the so-called overlap notch 409, which occurs approximately 90 m5 after the EKG indicates diastole.

For convenience, the device is normally triggered by detecting the protrusion 415 of the E K G.

From FIGS. 4A and 4B, one advantageous method of using the above-mentioned phenomena for fading and controlling a device is shown in a connection diagram, which will be explained in more detail as follows.

A transducer-type pressure detector 34 including a sensing bladder 35 is used to detect water pressure within the bladder 22.

If the pressure thus sensed is less than 20w1 of mercury, pressure level amplifier 46 provides an output to AND gate 48.

During this low pressure signal situation, when the user presses the water fill switch 50
to close, a signal is sent by AND gate 48 which operates fill pump 52 through pump control circuit 54 and simultaneously closes multi-position solenoid valve 56.
is moved to its filling position, i.e. from conduit 58 to conduit 6.
The position is such that water flows to zero.

Water thereby flows into the bag 22 until a pressure of 20 wIlHg is detected by the pressure sensor 34.

The signal from amplifier 46 then drops, thus closing AND gate 48.

Fill pump 52 is thereby deactivated and solenoid valve 56 is moved to the off position.

A similar device in which the pressure is detected by a detector 62 is used to drain the water from the bag 22.

In normal operating mode, the detected pressure is 11511m
If the value of Hg is higher than the value of Hg, the signal is AND gate 6
6 When the "feed out switch" 66 is closed, the signal command by the gate 64 operates the pump controller 68 and the "discharge pump" 69, and the solenoid valve 56 is moved to its position, i.e., the water is discharged. It is positioned to flow from conduit 60 to conduit 70 .

For purposes of illustration, the pump 69 pumps until a pressure less than 115M) (g) is detected.

At that time, AND gate 64 no longer detects the desired signal by detector 62, pump 69 is stopped, and valve 56 returns to the off position.

It will be appreciated that the filling and emptying operations described above are generally used at the beginning and end of use, and not as a continuous eleven-leg device.

Nevertheless, it is emphasized that the ability to fill bags to a certain predetermined pressure by an automatic device rather than a discriminator device is highly advantageous.

During operation of the device, the pressure within the bag 34 is maintained at the desired level by reducing the water in the bag device as follows.

The displacement detection type transducer 76 is connected to a hydraulically operated rod.
It is mounted on the cylinder device 78.

The transducer 76 is adapted to produce an electrical signal output proportional to the linear movement of the device 78 at any given moment;
Transducer 76 and rod and cylinder device 78 constitute a displacement device.

The normalized value of the position of the rod cylinder device 78 is:
It is obtained by feeding the signal from transducer 76 to displacement detector 80 .

The normalized signal is therefore provided to level comparator 82.

The second power of the comparator 82 is derived as follows.

E K G fi signals from the patient being treated are sent to trigger generator 84 .

The trigger generator is selected to recognize and react to so-called QR8 complex rising edges of the EKG signal.

(This rise is indicated by the number 415 in FIG. 4.

) That is, when the rising edge of OR8 occurs periodically with each heartbeat, it triggers an output to the manually controlled delay device 86.

The purpose of the delay device 86 is to convert the original signal from the first trigger generator 84 into a second time-delayed signal that corresponds in real time to the onset of cardiac diastole.

This second signal enters a continuous signal generator 88.

Generator 88 is selected such that the signal therefrom continues for the time period that requires foot pressurization (such as caused by pressure in bladder 34).

The delay device 86 and the continuous signal generator 88 are manually controllable manual controls that form part of a visually monitored phasing control system, and are used to control the relative timing of the pressure command signals appearing on the race and Visual adjustment of the signal is accomplished to adjust the duration and bring the signal into the desired correlation to the E K G trace.

This signal from the generator 88 is sent through a level stroke signal generator 89 to a level comparator 82.

The signal from generator 88 is also sent to waveform generator 90, which produces a waveform having an amplitude and frequency similar to that required for the foot pressurization sequence.

The standard waveform is 60 m5 rise and 250 ms
It has a ladder shape with a flat upper part and a drop of 60m5.

The waveform from this generator 90 is sent to a waveform comparator 92,
Here it is continuously compared to the signal obtained from the actual ball force wave received by the detector 34.

The output of comparator 92 is a so-called "error signal," ie, a signal representative of the quality and strength of the difference between the desired waveform signal from generator 90 and the actual waveform signal from detector 34.

The error signal is used to control servo valve 94 through servo amplifier 93, thereby controlling the liquid supply to rod and cylinder device 73, and thus device 78.
control the movement of

As mentioned above, level comparator 82 receives two signals, one being a periodic signal from continuous signal generator 88 to strobe signal generator 89 and the other being a signal from displacement detector 80. .

Displacement detector 80 compares these two signals, one representing the actual position of device 78 at a given time.

It is a periodic or "strobe" signal from a sustained signal generator 88 as modified by a level strobe signal generator 89 which determines when this comparison is to be made.

This comparison is most useful when the reciprocating member 30 is at the top of its travel and pushing firmly against the bag 22.

When the level comparator 82 detects that the reciprocating member 30 is too high, it is applied to a lower one shot (monostable multi-by-break) 96.

This one shot 96 then turns on the position solenoid valve 56 and fill pump 52 for a fill period of 0.5 seconds as well.

A filling period of 0.5 seconds is used for each cardiac cycle (i.e., each heartbeat) until the amount of water in the bladder 22 is sufficient such that the reciprocating member 30 is within the allowable displacement range at the top of its stroke. )
It is a lotus that continues inside.

Otherwise, when a signal is received by level comparator 82 indicating that reciprocating member 30 is too low in its stroke, the evacuation pump is activated each cardiac cycle 1 by operation of "one shot" device 98 and evacuation pump 69. / Turned on for 2 seconds.

Water is then pumped out of the bag until the reciprocating member reaches the desired height in its stroke.

The general operation of this device is as described above.

Here's how to get your movements to properly synchronize with your heartbeat.

The signal from the arterial pressure detection device 99 is transmitted to the EKG device 102.
Dual trace oscilloscope 1 with signal from
01.

While these signals increase, the pressure command signal received from the sustained signal generator 88 is present and the EKG trace 104
and appears as an increase in the arterial trace 106.

90 m5 delay device 108 and 80 ms delay device 11
0, the pressure command signal appears in both waveforms in approximately exact time relationship with respect to the actual E K G and arterial pressure.

Delay device 86 is used to register the enhancement signal during diastole, such as seen on an EKG or arterial trace, thereby aligning the pressurization wave with the cardiac cycle.

The user of the device may change the characteristics of the sustained signal generator 88 to
A variable control device may also be used to sustain the augmentation signal as needed for a particular patient.

On the oscilloscope 101, this sustained signal is shown as an oscilloscope trace enhancement 103.

It is observed for the waveform generator 90 that a typical generated wave will always have a total positive pressure period of about 250-300 m5.

The rise and fall of pressure takes about 60 m5, and the rise begins about 80 m5 before cardiac diastole.

Generally, it is desirable to choose a period determining device that can maintain a positive pressure period of approximately 150-500 m5.

FIG. 4C is an alternative view to FIG. 4B and may be used with particularly advantageous control devices such as those described below.

This above-mentioned control device is based on the premise that a specific artery detection part such as the wrist is selected in advance and operated optimally.
Its optimal operation is approximately 80
This refers to the case where the m5 front phase is out of phase.

Between the EKG case and wrist detection, the aforementioned 90m5
To avoid the need for preselection of a given delay like
The following equipment will be used:

The signal from the EKG device 102 is a signal from the EKG device 102.
4, a delay device 86, and a sustaining signal generator 88 to an 80m5 delay device 110 as previously described.

The output from delay device 110, a pulse of duration D4, is delayed from the R wave by a time DI (carried by delay device 86) plus 80 m5.

This pulse is used to obtain EKG (channel 1) enhancement.

This pulse is also supplied to a variable delay device 112, which outputs a signal at times D1 and 8.
It is delayed from the R wave by the sum of 0m5 and D2.

Here D2 is a variable delay created by variable delay device 112.

By the way, the trigger signal from the trigger generator 84 is 4
0 m5 delay device 114 and thus a variable delay device 116.

The output from variable delay device 116 is output to marker generator 118.
This marker generator 118 is supplied to D2 and 4.
0m5, a marker pulse delayed from the R wave is generated.

Here D2 is the variable delay delivered by variable delay device 116.

The signals from marker generator 118 and delay device 112 are
A pulse mixer 120 is fed and the combined signal is fed to the channel 2 trace of the oscilloscope (the channel representing the arterial waveform).

In operation, 414, 415 in FIG. 3A originates from generator 118 and depends on the position of artery detector 99.

Marker pips, alternately shown as or 416, are moved along the arterial trace 106 to a position, eg, shown as 414, where cardiac contraction is initiated.

This position is characterized by a rapid onset of rise in the arterial trace.

The marker pip can be moved using marker position control 122 over a range equal to the D2 variable delay time provided simultaneously by delay devices 112 and 116.

As the marker pip is so moved, an augmentation trace produced by the sustained signal generator 86 and representing the external pressure aid stroke follows the marker pip or is delayed by a time Dl-40ms behind the marker pip. .

In use, the user of the device first views the arterial trace, adjusts the marker position control 122, and moves the marker pip to its desired position indicating the onset of cardiac contraction.

This time is equal to the delay imparted by variable delay device 116 plus 40m5.

The variable delay device 86 or Dl then controls the delay controller 124
By adjusting , the enhancement signal is set to match the overlapping notch, ie, the shape of the pressure seen immediately following small descending deflections in the arterial wave or semilunar valve closure.

Finally, the sustain signal generator 88 is set to provide the appropriate pulse length by adjusting the sustain controller 126, thereby phasing the pressurization wave and the cardiac cycle.

As seen in FIGS. 5A-5C, the mechanical actuator 510 includes a reciprocating member 512 that is pivotally mounted at one end at 514 and connected to a mechanical linkage 516 at the other end.

This reciprocating member 512 is attached to the frame 522 of the mechanism at 52
Hydraulic cylinder 518 supported for pivoting at 0
operated by.

The other end of the cylinder 518 is also fixed to the operating shaft 528 of the link device 516 by a bolt 524 and a yoke 526.

The operating shaft 528 further includes two generally triangular cam bearings 5.
30.

Cam 530 is mounted for pivoting about axis 532.

Thus, when the plunger 534 of the hydraulic cylinder 518 applies a force to the operating shaft 528, the triangular cam is caused to rotate clockwise about the shaft 532.

This causes arm 538 of cam 530 to be lifted.

At the same time, lever arms 53 are mounted for pivotal rotation relative to cam bearings 530 on each side of reciprocating member 512.
9 is adapted to lift the reciprocating member 512.

The surface of reciprocating member 512 has been partially removed from FIG. 5A so that a diaphragm or bellows 541 can be seen attached between frame 522 and reciprocating member 512.

The lower part of the bellows 541 is attached to the flange 544 seen in the isA diagram.

Flange 544 is the top of bellows support structure 543 that is attached to bottom plate 546 and together with bellows 541 constitutes a device that occupies most of the volume between the bottom of bottom plate 546 and plate 512, thereby providing a linkage device. 516
A housing is constructed for the

A seal 547 is provided around the opening through which cylinder 518 passes through bellows mount 543.

An outlet for the gas leaving the bellows is provided by an exhaust passage 550.

In operation, member 512 pivots up about 514 as plunger 534 is caused to rest against actuation front 528, thereby causing triangular cam 530 to rotate clockwise.

Air is then drawn into the bellows 541 from the atmosphere.

Conversely, when the reciprocating member is pulled down by retraction of the plunger and the volume occupied by bellows 541 is compressed, air is expelled from exhaust passage 550.

Improved control is achieved with this method, especially when the equipment is operated at sub-atmospheric pressures, i.e. when the equipment is enclosed in a bag, as shown at 557 in Figure 1, where the vacuum is partially removed. It is.

Additionally, it has been found to be particularly advantageous for the linkage system to minimize stress on the inside of the foot housing 554 as seen in FIG.

In order to understand the advantages of the special construction of the linking arrangement shown here, reference should be made to the arrangement of FIGS. 5A, 5B and 1.

Of course, any significant deflection of foot unit housing 554 by bladder 552 must be avoided.

If the housing 554 is not rigid, its expansion will make desirable control of the pair expansion cycle difficult or impossible.

As can be seen, the operation of the mechanical actuation unit is ideally such that it minimizes expansion forces on the housing 554.

For example, when the reciprocating member is directed upward by the action of a hydraulic cylinder and a mechanical linkage, a force 560 is applied to the mechanism of the reciprocating member itself and thus to the foot unit holding the mechanism.

With the mechanical actuation system of the present invention, the bottom plate 546 is much lighter because it can only withstand the tensile strength provided by vector 560 shown in FIG. 5B, for example.

These forces place the bottom plate 546 in tension, but do not subject it to any significant bending stress.

Further, when the two parts of the foot unit are held together by quick disconnect bolts screwed into rods 556 and 558 as shown in FIG. 6 and seen in FIG. 5B, the upper and lower segments of the foot unit Any normal force that tries to separate the rod 556
and is recorded as the tensile stress at 558.

Again, there is no moment attempting to impart vertical bending motion at points 564 or 566.

The foot portion of the housing 554 is adapted to dissipate stresses in its circular structure as a circular stress distribution, thereby substantially eliminating any strain due to said stresses.

As a result of the relative lack of bending moments and said force distribution in the structure of the invention, the housing unit can be made of much lighter materials than before.

As shown in FIG. 2, a rigid housing or casing 24 is used to enclose the bag and its mechanical pressurization device.

This casing must be as light as possible without compromising its stiffness.

As seen in FIG. 6, foot casing 24 has a single upper foot casing member or shell 131 and a single lower foot casing member or shell 132.

The shell is conveniently made of a plastic material and internally reinforced with a hard, low density, organic resin foam, such as Polyurethane Home 134.

A particular advantage of casing 24 is that it is a quick connect and quick disconnect device.

The footrests are generally mounted between chambers 135. Bolt connectors 136 are constituted by bolts permanently located within upper shell 131.

The bolt has a large head to facilitate quick connection by threading into the lower shell 132.

The latch connectors mounted along the outer peripheries of the lower and upper shells have pins 140 that are attached to pins 140 when the connector member 144 is moved downwardly.
0 and is placed over the connector member 142 such that once lowered, it taps into the opening 146 of the pin member 144 by lateral movement of the upper shell.

Once this latching action is achieved, Pol l-13
6 can be tightened and the operation can proceed.

Another important aspect of the invention is that it can combine a relatively simple structure with only one liquid bag, an upper casing member and a lower casing member, yet provides a device suitable for excellent pressure control. It is possible to do this.

This has been achieved by having each truncated semi-conical footrest comprising one upper foot casing member 131 and one lower foot casing member 132 having two chambers 135.

These chambers are connected by a thinner tube (see Figure 1), which allows a single blanket-like bag to be wrapped around the patient's foot.

In order to avoid any significant deflections due to the bag (for example deflections of more than about 1.5 degrees at the midpoint of the pressure), a triangular reinforcement is provided between the foot enveloping chamber and the casing member to hold them together. It turned out that it was necessary to connect to

This method allows the reinforcement to be made from a lightweight plastic material, such as polyester reinforced with fiberglass.

The band surrounding the foot itself tends to withstand considerable deflection and deformation because its conical shape resists circularly distributed stresses.

The connector 136 of FIG.
is connected to the lower reinforcing portion 152.

The upper reinforcement portion is made of resin-type honeycomb material 154.

The necessary electrical and hydraulic connections are made through the outer shroud 36 and casing 24 as required.

In an illustrative embodiment of the invention, the surface area of the reciprocating member is approximately 600 d and its stroke is approximately 5 cIrL.

This device has a displacement capacity of approximately 3000 Cwt, which is perfectly suited to the displacement demands arising from the compressibility of the patient's foot, and when combined with a pressure wave monitoring and control device as described above, certain limited Structural materials with expandable properties can be used.

Generally, the reciprocating member and its actuator should be selected to have a displacement capacity of at least about 100 cubic inches.

The vertical stroke of the reciprocating member is conveniently kept below about 9 crrL to avoid excessive speed and associated design control problems with mechanical resistance and hydraulic inertia.

[Brief explanation of the drawing]

FIG. 1 is a detailed sectional view of the device of the present invention for placement on a patient's foot; FIG. 2 is a plan view of the foot wrapping device cut open to show the position of the reciprocating member; FIG. 3 is a plan view of the device of the present invention; is a chart showing the relative timing of physiological events with respect to the explanation of
Figure 3A is similar to the curves that would appear on a two-channel oscilloscope, including the electrocardiogram curve and several alternative curves representing the heartbeat as expressed by pressure in the central aorta, radial artery, or fingers. FIG. 4A and FIG. 4B collectively constitute a connection diagram of a unique control device used in the external pressure circulation support device, and FIG. 4C shows a connection diagram of an alternative device to the device shown in FIG. 4B. Figure 5A
5B is a plan view of a mechanical actuator made in accordance with the present invention with the upper bearing portion removed to better show the components of the device, and FIG. 5B is shown in FIG. 5A with the device in the upward or extended position. FIG. 5C is a side elevation view of the device shown in FIG. 5B with the device in a retracted position, and FIG. 6 is a side elevation view of the device shown in FIG. FIG. 3 is a perspective view of the device for quick connection of the casing; 20...foot, 22...bag, 23...
...Water, 24...Casing, 26...
...Upper member, 28...Lower member, 30...
...Reciprocating member, 34...Detector, 36...
... Enclosure, 39... Suction pump.

Claims (1)

[Scope of Claims] 1. A device for applying external pressure type circulatory support to the patient's legs in a cycle synchronized with the patient's heartbeat by pressurizing the patient's legs, which includes: A. wrapping around the patient's legs; B. a mechanical displacement device in contact with the outer wall of said bag, said bag 22
a single T-section foot casing with a C0 single upper foot casing member 26.131, and a mechanical displacement device serving as a device for pressing and being the main device for obtaining the aiding action of said pressure; Member 28, 132
and a foot casing member having a reinforcement portion 150 between the foot members sufficient to avoid any appreciable outward deflection of the foot casing member during the pressurization of the fluid. An external pressure circulation support device consisting of: 2. The device according to claim 1, wherein the auxiliary portion comprises: A. Each of the foot supports of the upper foot casing member and the lower foot casing member is a triangular reinforcing portion between each of the chambers 135; , a plurality of fastening devices 140-146 for interconnecting the reinforcing members. 3. The device of claim 2, wherein the footrest has a truncated semiconical chamber and dissipates stresses applied thereto as circular stresses, whereby the footrest has a significant deflection of the chamber. or a device adapted to resist deformation. 4. Apparatus according to claim 1, wherein the casing member, the bag and the displacement device are all arranged within an enclosure so as to maintain a pressure below the ambient atmosphere. 5. The apparatus of claim 3, wherein the pressurized device has a displacement capacity of at least 1,639 i (100 cubic inches) and said reciprocating device has a displacement capacity of at least 1,639 i (100 cubic inches) and said reciprocating device has a displacement capacity of at least 1,639 i (100 cubic inches) and A device comprising a device for actuating a moving member. 6. A device according to claim 1 for providing a circulatory aid action by external pressure to a patient's limbs in a cycle synchronized with the heartbeat of the patient, wherein the aid surrounds the limbs. An apparatus for transmitting pressure to said limb through a fluid-filled bladder, comprising: A. B. a device for visually displaying the relative duration of the pressure command signals appearing on said trace; and C. adjusting the relative timing and duration of said pressure command signals. and a manually controlled phasing control device 86.88 for simultaneously effecting visual adjustment of said signal to bring said signal into the desired correlation with the E K G trace. . 7. A device according to claim 1 for providing external pressure circulatory assistance to a patient's limbs in a cycle synchronized with the patient's heartbeat, the aid comprising a fluid-filled bladder surrounding the limb. Pressure is applied via hydraulic cylinder 518
A. an ideal pressure waveform generator 90; B. an actual ball rental waveform detection device 34, 35; and C. a waveform comparator 92 for continuously comparing the ideal waveform and the actual waveform; D. responsive to signals from said comparator, altering fluid flow to said hydraulic cylinder, thereby said and a servo valve 94 that more closely achieves the ideal pressure waveform.