US3014480A - Respirator - Google Patents

Description

Dec. 26, 1961 w. A. GARDNE'R 3,014,480

RESPIRATOR Filed Jan. 25, 1960 "f M ve/ INVENTOR.

P19515' 5 URE /A/ 46 rates 3,014,48ll RESPIRATR William A. Gardner, lill?, Cypress St., Duncan, Okla. Filed lan. 25, 1960, der. No. 4,415 4 Claims. (Cl. 12S-263) ample of such a respirator' is found in the U.S. patent to Halliburton No. 2,774,346 of December 18, 1956.

ln addition to breathing assistance, medicated aerosols may be added to the inspired gases to treat various respiratory disorders. Medical uses for this type of equipment include resuscitation, long term breathing assistance on patients with respiratory paralysis, breathing assistance to any critically ill patient who might expire without the assistance, clearing obstructed lungs of patients with asthma, pneumonia, silicosis, bronchiectasis, mucoviscidosis, emphysema, and other respiratory disorders.

In such respirators, valves are used to control the flow of gases to the patient, but some valves are not adaptable to all of the treatments mentioned, and are limited to treatment of patients who are physically able to suck and blow enough to cycle the valves.

- The ideal respirator valve should provide effortless or automatic breathing when needed and should never interfere with the patients breathing efforts. It should also be able to ventilate the lungs of persons with restrictions in their airway. It should also operate with slight leal;- ages in the patients mask, tracheostomy tube, or other fitting.

In the respirator of the Halliburton patent, mentioned above, a variable dead weight, or a spring, exerts a force on a poppet valve. This allows balancing against variations in pressure in the gas to be inhaled. However, if the pressure ofthe gas is changed without making a compensating change in the load on the valve, a change in the effort of the patient is needed to start each breathing cycle. The valve can be adjusted to open with any desired suction effort, or cycle automatically when expiratory pressure reaches a desired minimum above Zero; and operators who understand these adjustments are pleased with the versatility of the valve. Despite this versatility, sales of the Halliburton respirator have been limited because the balancing procedure is confusing to most operators. Another objection to the automatic cycling feature of the Halliburton respirator is that there is no pause between exhalati-on and inhalation. This results in a rapid breath-` ing, which often removes too much carbon-dioxide from the patient, and creates nervousness and muscular spasms (alkalosis) The objects of the present invention are to provide a respirator that is not affected by variations in gas pressure; that can be cycled by any desired amount of patients suction effort; that can be cycled automatically with an adjustable pause between exhalation and inhalation; that can be set to remain open at a very low flow rate to ventilate the lungs through congested air passages; that can be set to close at higher minimum flow rates to compensate for leaks around masks, tracheostomy tubes, etc.; that always assists and never interferes with the patients breathing efforts; and that requires a minimum of skill and instruction for operation.

@ther objects and advantages reside in the particular combination of elements and arrangement of parts, as will llii@ Patented Dec. 26, 1,961

become apparent from consideration of the following description of the preferred embodiment of the invention, when taken in connection with the accompanying drawing, in which:

FIGURE 1 is a front elevation of a respirator constructed in accordance with the principles or the invention.

FIGURE 2 is a fragmentary sectional view taken substantially on the line 2-2 of FIGURE l, illustrating the position of the parts -of the valve mechanism during the final phase of the expiration period.

FIGURE 3 is a typical breathing curve that can be produced by the respirator of the present invention, showing the phases that can be adjusted to suit the patients needs.

Referring now to the drawings and particularly to FIG? URE 1, the respirator of this invention includes a casing lill which houses a pressure regulator having a contnol knob l1, and a control pressure gauge 12. Inasmuch as the pressure regulator and gauges are of conventional form, they need not be described in detail.

Secured to the casing 1l) and connected to the regulator outlet is a differential breathing valve i3. The breathing valve l outlet line has a T adapter ld which allows a nebulizer l5, which is controlled by a needle valve 16, to spray moisture and medication into the gas emitted from the breathing valve 13. A flexible conductor tube 17 delivers the pressurized and medicated gas to a mask 18 or other connector to a patient.

An exhaust valve 2d is connected to the tube 17 near the mask 18. The exhaust valve 20 is pneumatically controlled by a tube 2l, which is connected to a sleeve valve system in the breathing valve i3. Sealing in the valve Z'Il is effected by a flexible balloon 49 of well-known design.

The positive and negative pressure in the mask 18 is registered on the gauge 22. The entire unit is connected to a source 25ct pressurized gas by means of the tube 23, or other suitable connection. The tube 23 contains gas under continuous pressure, but which may vary, for example, from twenty pounds per square inch to one hundred pounds per square inch. On the other hand, the tube A 17 delivers intermittent positive pressure to the patient at adjustable pressures varying, for example, from five to fifty centimeters of water, as needed. The regulator 2d reduces the pressure of the gas in the cylinder 25 to the range to be maintained in the tube 23.

Referring now to FIGURE 2, it will be seen that the body of the respirator valve 13 contains a valve seat 31 located below a larger cylindrical chamber 32. A differential poppet 33 rests7 under the influence of gravity, on the seat 3l and serves as a poppet valve.

A manually operated handle 55 may be connected to the poppet 33 to open andclose the valve 13 when de.- sired.

The upper section of the poppet stem contains an undercut or reduced portion 34, that acts as a sleeve valve in the cap 35 to open vand close the port 36,.thereby Aallowing the exhaust valve 20 to open when the poppet 33 is seated, and close when the poppet 33 rises.

The top of the poppet ste'mis provided with a piston 37, working in a cylinder 37a fixed to the cap 35 of the valve i3. The effective area of the piston 37 is equal to the effective area under the valve seat 31.

The intake .chamber 39, below the seat 31 communi-- cafes with theinterior of cylinder 37a, above the piston 37, through a port 33 in the stern of the poppet 33, thereby balancing the poppet 33 to all pressures in the intake chamber 39.

A spring 40 is provided to urge the poppet 33 upwardly,

and

and thus allow the poppet 33 to rise and fall freely. A small amount of pressurized gas above the piston 37 will intentionally leak through this clearance.

It is apparent that any pressure above atmopsheric under the piston 37 will have an upward force on the piston 37 and tend to raise the poppet 33 from its seat 31 to start a breathing cycle. Pressurized gas under the piston 37 will also upset the balance between the piston 37 and the valve seat 31 and thereby preven-t the poppet 33 from seating to close the respirator valve 13. Thus the operation of the poppet can be controlled by controlling the pressure under piston 37.

The gas that leaks around the piston 37 is therefore conveyed to the atmosphere through the vent port 42 and a tubular hole 43a in a plunger 43. Means is provided for temporarily blocking of the vent port 42. Blocking port 42 will open the respirator valve 13 by the upward force of trapped pressurized gas under piston 37. This principle is used to provide an automatic time cycling means for the respirator valve in a manner that will be described hereinafter.

The plunger 43 has a piston 62 iixed thereon which works in a cylinder 63. The space above the piston 62 is exposed to the atmosphere at all times, there being holes 63a in the head of the cylinder 63.

Movement of the plunger 43 downwardly, to block passage 42, is caused by the action of gravity thereon.

Upward movement of the plunger 43 is caused by the exertion of gas pressure under the piston 62. To this end the space in cylinder 63 below the piston 62 is controlled by the gas pressure in the chamber 4S on the downstream side of the poppet 33.

The space below the piston 62 is connected to the chamber 48 by a passage 46 under the control of a disc check valve 45. During the inhalation period, pressure in the chamber 48 causes gas to enter the space below the piston 62 through the passage 46, and this forces the plunger 43 up. The plunger 43 remains in the up position until the nal phase of the exhalation period. When the pressure in the chamber 4S falls below a predetermined amount, say three centimeters of water, the plunger 43 starts to fall.

The time required for the plunger 43 to fall is controlled by the rate of escape of gas from the space under the piston 62 past the needle valve 44 in an outlet passage 47.

When the plunger 43 crosses the vent port 42, it closes port 42. Thus plunger 43 is, in fact, a pressure controlled sleeve valve. When plunger 43 drops to its lower position, gas is trapped under piston 37. The trapping of pressurized gas under the piston 37 pushes up on the poppet 33 to start another breathing cycle.

If the patient creates any suction or inhalation effort before the plunger 43 blocks the vent port 42, the slight negative pressure in the chamber 48 will raise the poppet 33 to start another breathing cycle. Accordingly, it will be obvious that the automatic cycling action of the plunger 43 does not interfere with the patient initiating a breathing cycle at will. If the patient fails to initiate a breathing cycle during the rest period, which is adjusted by the needle valve 44, a breathing cycle will be automatically initiated when the ventwport 42 is blocked by the sleeve valve action of the plunger 43.

The automatic cycling arrangement can be set to insure a minimum number of breaths per minute needed to obtain adequate ventilation, even on patients who are physically able to cycle the valve by initiating asuction effort. This is important in patients with chronic` respirator disorders, who are inclined to underbreathe when breathing oxygen in higher concentrations, thereby accumulating carbon-dioxide to the toxic level.

From the above description, it will be understool that the breathing valve 13 will remainin the closed position shown in FIGURE 2 until a slight negative pressure or suction eifort exists in the chamber 48, or until blockage of the port 42 by the plunger 43 upsets the pressure balance, thereby forcing poppet 33 up from the seat 31. When the poppet 33 rises from the seat 31, the exhaust valve 20 closes due to equal pressure in the balloon 49 and the chamber 48 by communication through the port 36 and the tube 21. The unseated poppet 33 also exposes its large cylindical flanged area in the chamber 32 to the pressure in the chamber 39. This increased area exposed to the incoming pressure causes an increase in the lift or upward force on the poppet 33, thereby holding the poppet 33 up until the pressure in the chamber 48 approaches the pressure in the chamber 39. The flow rate of gas from the chamber 39 to the chamber 48 is proportional to the differential pressure between these two chambers. When this flow rate reduces to a desired minimum, the poppet 33 falls to the seat 31, thereby closing the port 36, allowing the balloon 49 to deate through the bleed hole 50, and this opens the exhaust valve 20.

The desirable minimum flow rate at which the breathing valve 13 closes will vary with the patient and the condition. Patients with obstructions in their bronchial tree will obtain much better ventilation with a valve that remains open at a very low ilow rate (less than five liters per minute). Leaks around the mask or patient fitting will prevent a valve that remains open at a very low flow rate from closing until the patient blows against the incoming pressure enough to overcome fitting leaks. This is very tiring on the patient, and the increased pressure in the lungs results in a reduction of blood flow through the lungs (cardiac output).

To satisfy all minimum ow rate conditions, leakage holes 6) are placed in the cylindrical ange area of the poppet 33. These holes can be wholly or partly closed by a disc 61, which has holes matching those shown at 60, or other suitable means. In this manner the minimum ow rate at which the poppet 33 will fall and seat is adjustable. When all leakage holes 6G `are closed, the poppet is very sensitive to flow and will remain up until the flow rate is less than tive liters per minute. If the leakage holes 6) are partly uncovered, on the other hand, the minimum flow rate can be increased accordingly. This allows compensations to be made for leaks.

Plugs or other suitable means can also be used to close the leakage holes 60 and obtain the ilow sensitivity needed for the patient and the littings. For example, some physicians use a tracheostomy tube with an inatable cui to provide an airtight seal in making a connection to a tracheotomy case. Other physicians prefer to use a large tracheostomy tube with a minimum amount of annular space between the tracheostomy tube and the trachea. This results n leaks through this `annular clearance which must be compensated for by opening leakage holes 60 in the poppet 33.

The piston operated plunger 43 need not be used under some conditions, and it may be provided with a suitable lock or catch (not shown) which can hold it in an upper or open position. When the valve 43 is locked in the open position (or if it is eliminated entirely from the aS- sembly), the Irespirator will still function under some conditions of use. The valve 13 will open with a slight effort on behalf of the patient independently of the pressure in the inlet 39, since the pressure on the poppet 33 is balanced, the piston 37 being of the same area as the seat 31. The valve 13 will remain open until the ow rate of the gass reduces to a desired minimum.

It is pointed out however, that the sleeve valve 43 and its components, provides an automatic timing cycle for patients who are unable to `start each breathing cycle by a slight inspiration effort, as well as insuring an adequate number of breaths per minute to patients who are inclined to underbreathe and yaccumulate carbon-dioxide in their systems.

The design of the poppet 33 is such that whenever it rises, it remains open for some time. This is due to the differential area between the wall of the chamber 32 and the area of the seat 31. During the time that the poppet 33 is open, pressurized gas flows from the inlet chamber 39 through the outlet chamber 48 to the patient.

FIGURE 3 shows'a breathing curve that can be produced by the described respirator, in which pressure in the chamber 48, which is essentially the same as that in the mask 18, is plotted against time. This curve is theoretical only, and is for purposes of illustration of the oper ation of the respirator. During the rest period between d and a, the breathing valve 13 is closed and there is no pressure above atmospheric in chamber 48. The time or length of this rest period can be controlled by the patient or by the needle valve 44.

When the patient initiates the breathing cycle, a slightly negative pressure (i.e. slightly less than atmospheric) exists in chamber 48. This is indicated by e. When the breathing cycle is initiated by the sleeve valve action of plunger 43, the pressure in chamber 48 does not fall below atmospheric. The valve 13 opens when the pressure in chamber 48 is reduced to atmospheric.

The rate of rise of the curve between a and b indicates the flow rate to the patient during the initial phase of the inspiration period. This is completely controlled by the patient. Lung capacity and resistance to flow by airway restrictions and lung compliance with vary with each person. As the pressure in chamber 43 approaches the pressure in the chamber 39, the -ow rate will slow down. The minimum flow rate needed to hold the breathing valve open is indicated on the curve by the curve rise between b and c.

When all of the leakage holes 60 are blocked by the disc 61, b and c will become a horizontal line. The distance between b and c in this case will depend upon the instant when the patient blows against the pressure in chamber 48 to close the breath-ing valve 13. As holes 60 are opened, the minimum ow rate at which the valve 13 closes will increase accordingly, and the rise between b and c will become steeper. This will also shorten the distance between b and c since the valve 13 will close when flow to the lungs reaches a higher minimum. If leaks around the patient fitting compensates for leaks through holes 60, the shape of the curve between b and c will continue to be relatively at.

A curve that is relatively flat between b and c is called a high ow sensitivity curve and this is considered ideal for patients who are congested or have other resistances to ventilation.

By opening the holes 60 in the poppet 33, the breathing curve can be varied from a horizontal line between b and c to a sharp drop oi as indicated by the dashed line between b and f.

The point c on the curve indicates the point at which the breathing valve 13 closes and the exhaust valve 20 opens. The initial expiration rate is rapid but it slows as it reaches the line of zero pressure in chamber 48.

l This is patient controlled and will vary depending upon the maximum mask pressure and the elasticity of the lungs.

When set for automatic cycling, the plunger 43 will start to fall at about the point h on the curve. This is dicated by the horizontal distance between h and a. This i time is regulated by the needle valve 44. If the patient fails to initiate another breath, as indicated by e, the sleeve valve action of the plunger 43 on the vent port 42 will initiate another cycle as indicated by the point a. n

It is within the purview of the invention to use diaphragms instead of pistons. For instance, the piston 37 could be a bellows with a hole therein to provide a certain amount of leakage. Also the piston 62 could consist of a diaphragm yieldably iixed to the `wall of the cylinder 63. Various other changes could be made in the arrangement and construction of parts without departing from the spirit of the invention or the scope of the annexed claims.

I claim:

1. In a respirator, having a source of gas under more than atmospheric pressure, a supply line and a mask, or the like, for supplying the gas to a patient in cycles, the combination consisting of a breathing valve having a differential poppet valve connected into the supply line and adapted to intermittently open and close, said poppet valve separating said supply line into an upstream side and a downstream side, a cylinder mounted on said breathing valve, a piston fixedly connected to said poppet valve and somewhat loosely tted in said cylinder so that slight leakage of gas can .take place around the piston, means for supplying gas from the supply line to space in the cylinder on one side of the piston, and means for exposing the other side of the piston to the atmosphere, whereby the piston and cylinder exert a slight force upon said poppet valve tending to close the same so long as one side of said piston is exposed to the atmosphere.

2. The combination with the arrangement defined in claim l of an adjustable valve and means for connecting it to said other side of said piston, said adjustable valve serving to control the leakage of gas past said piston.

3. The combination with the arrangement delined in claim l of means providing a chamber on the downstream side of saidpoppet valve, an additional valve for controlling the leakage past said piston, and means connected to said chamber and associated with said additional valve for closing the same when the pressure in said chamber reaches a predetermined pressure level. v

4. The combination with the arrangement defined in claim 1 of means in the poppetvvalve for providing'a minimum flow rate of gas to the patient when the poppet valve is open, said last-mentioned means being adjustable.

References Cited in the tile of this patent UNITED STATES PATENTS

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