US3807446A - Respirator system - Google Patents

Abstract

A respirator system for delivering accurate portions of pressure regulated gas at a controlled flow rate consisting of a gas delivery system having two chambers with communicating liquidfilled sections separated from gas-filled sections with a valve disposed to alternately fill one chamber with gas thereby delivering a portion of gas at the outlet of the other chamber equal to the volume of the liquid displaced and at a rate determined by a flow regulator in the liquid section of the system. The respirator system also includes a control system that monitors the output of the gas-delivery system as well as monitors the respirator performance of the patient.

Description

[ 75] Inventors:

RESPIRATOR SYSTEM Thomas D. Driskell, Worthington; Craig R. Hassler, Columbus, both .oQfQIJQMM 1451 Apr. 30, 1974 3,515,133 6/1970 Parker 128/1427 X 3,568,214 3/1971 Goldschmied 417/389 X 3,633,217 l/l972 Lance 417/389 X 3,630,644 12/1971 Bellhouse et al. 417/389 Primary Examiner-Henry T. Klinksiek [73] Assignee: Battelle Development Corporation,

I Columbus, Ohio Attorney, Agent, or F1rm-Stephen L. Peterson [22] Filed: June 5, 1972 [57] ABSTRACT [21] Appl. No.: 259,874 A respirator system for delivering accurate portions of pressure regulated gas at a controlled flow rate con- [52 us. c1. 137/561, 417/389, 73/219, 1 a 't Y havmgwo Chambers 60/54 5 R 137/554 37/625 24 128/142 8 w1th communlcatmg l1qu1d-filled sections separated 5] I t Cl lrmb 17/60 from) 35/62 from gas-filled sections with a valve disposed to alterl n nately fill one chamber with gas thereby delivering a [58] Field of Search 137/554, 62521-62524,

portion of gas at the outlet of the other chamber equal l37/625.43, 625.47; 417/383, 389; 60/54.5 t th I fth l d d t t d R- 73/219- 128/ 42 2 142.7 142 8 P ace a e termlned by a flow regulator 1n the 11qu1d sectlon of the system. The respirator system also includes a con- [56] Ref-erences C'ted trol system that monitors the output of the gas- UNITED STATES PATENTS delivery system as well as monitors the respirator per- 590,861 9/1897 Severy 60/54.5 R formance of the patient. 1,538,427 /1925 Earl 60/54.5 R x 2.907.349 10/1959 White 137/625.24 x 6 Clalms, 3 Drawing Flgllres 2,966,668 12/1960 Hillman et al. 137/554 X 3,421,373 H1969 Ardoino 73/219 FLOW REG.

23 r21 E 1:. T 3 12- 3s RECIPIENT 38 37 34 4! 40 4a 47 PRESS REG. T0 CONTROL SYSTEM PATENTEDAPR 30 I814 3.807;446

sum 1 [1F 3 TO RECIPIENT PRESS. CP 35 REG. TO CONTROL SYSTEM 7 1 RESPIRATOR SYSTEM BACKGROUND OF THE INVENTION The quantity of gas delivered to .a recipient during one inspiration is normally termed the tidal volume. The prior art devices are normally capable of delivering large tidal volumes of breathing gas for use with adult recipients that normally require gas volumes in the order of 300 cubic centimeters per inspiration. The

prior art, however, does not disclose adequate means to deliver small quantities of breathing gas to recipients requiring small tidal volumes. Where the prior art deals with small tidal volumes it is inherently-difficult to control flow rates and volumes of breathing gas in a cyclic manner to an infant recipient in respiratory distress. The difficulty arises since the means to control the operation must receive control information from small quantities of low pressure gas. While the fluid mechanics of compressible gases is well understood the actual control of gas deliverybased on low pressure measurements is inherently inaccurate.

The present system successfully alleviates the control problems inherent in the prior art by utilizing a gas delivery system where thedisplacement of a liquid controls the delivered gas volume and flow rate. The gas delivery system uses a conventional gas pressure regulator to control the pressure in the gas delivered.

The control system for the respirator system allows the selection of several modes of operation and includes means for changing modes dependent on the respiratory behavior of the gas recipient. The control system is designed to change modes of operation and to progressively revert to the simpler modes of operation upon failure of any one component or subsystem.

BRIEF SUMMARY OF THE INVENTION The gas delivery system consists of two chambers having means within the chambers to separate the chambers into two sections. One section in each chamber is filled with a liquid and those two sections have a means of communication whereby liquid is displaced from one chamber section to the other. The volume of the liquid is set so the displaced volume of liquid equals the desired tidal volume. A means of regulating the liquid flow in the communication between the fluid chamber sections determines the flow rate of the gas delivered. Both the control of tidal volume and flow rate are inherently more accurate than those dealing with gases since the controlling medium is of a constant volume and is incompressible.

It is the object of the present invention to deliver accurately portioned volumes of breathing gas regardless of requirements for small tidal volumes. It is another object of the invention to provide accurate flow rate control of the delivered tidal volume of gas.

It is a further object of the present invention to provide an accurate and inherently simple means to adjust the volume of delivered gas.

Another object of the present invention is to control the gas delivery in several modes of operation with the control system responsive both to the conditions of the gas delivery and the response of the recipient.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of the gas portioning system.

FIG. 2 is a schematic view of an entire respirator system utilizing the present invention as a means of portioning quantities of breathing gas and a control system for the control of the respirator system.

FIG. 3 is a schematic view of the control system used with the gas portioning device in a respirator system.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates an embodiment of the gas system having two chambers 20 and 21 with each chamber having liquid-filled sections 22 and 23 and gas-filled sections 24 and 25. The two sections 22 and 23 are separated from the gas sections 24 and 25 in this embodiment by flexible diaphragms 30 and 31. The two liquidfilled sections 22 and 23 communicate by way of pipe 26 which includes a means of controlling the flow rate of the liquid as it passes between chamber sections 22 and 23 shown here as the flow regulator 27. Also in the pipe 26 is a valve 28 for extracting a volume of liquid from the pipe as will be described subsequently as a method to control the tidal volume of gas delivered.

The gas supply portion of the system consists of a source of constant pressure gas shown here as the pressure cylinder 32 with an associated shutoff valve 33 and a pressure regulator 34. The pressure regulated gas is directed to a valve 40 shown here as a rotary valve having connections to gas sections 24 and 25 as well as an output line 36 leading to the recipientof the gas. The function of the valve 40 is to supply pressurized gas to the gas section on one chamber (as for example, 24) and thereby displace the diaphragm so as to deliver a volume of gas in the other gas section (25 in FIG. 1) equal in volume to the liquid displaced from section 22 to section 23. Through the rotation of the central member 41 of the valve 40 it can be seen that when the member 41 has been sufficiently rotated the source of pressurized gas is applied to the diaphragm in the opposite chamber at that time having a large liquid section. The liquid is then displaced back to the other liquid section whose corresponding gas section delivers another volume of gas.

It should be noted that the delivery of the gas to sections 24 and 25 will depend on how the valve 40 is constructed. The locations of the cut-away portions of the valves central member 41 relative to the input locations of members 35, 36, 37, and 38 will determine how long the gas pressure is applied to each chamber for any given rotational speed of the central member. The use of a rotating valve such as shown in the figure has the advantage of being easily controlled through use of conventional rotational motors and controls; however, there are linear slide-type valve systems that can provide similar switching functions. While the valve 40 determines the cyclic delivery rate by the speed of rotation of the member 41 a slide-type valve would have to reciprocate at a controlled rate to accomplish the same task. The rotary valve configuration has the added ad vantage of providing a source of rotation for control inputs that must be synchronized to the position of the main switching valve 40. Such inputs are shown schematically in FIG. 3. l

The control system may also have other components in the gas portioning system. lnFlG. 1 two sensors 45 and 46 are shown schematically and it is their function to indicate through leads 47 and 48 that the diaphragms 30 and 31 are at their stroke limits.

The tidal volume of the gas delivered is easily and accurately determined by first filling both liquid sections 21 and 22 to their capacity fully displacing the diaphragms 30 and 31. Valve 28 is then opened and a volume of liquid equal in volume to the desired tidal volume is then extracted from the liquid filled sections. When valve 28 is closed, alternate full displacements of the diaphragms 30 and 31 will deliver a tidal volume equal to the volume of the liquid removed with the gas being delivered at a rate determined by the flow regulator 27.

FIG. 2 shows the entire respirator system utilizing the gas delivery system in conjunction with a control system. The main switching valve 40 is driven by the rotary motor 50 which is controlled by a power source 53 and its associated control system 54 shown in this embodiment to be independent of the control system. The main switching valve 40 has a common drive to control valves synchronized with respect to the operation of the main switching valve 40. The functions of the separate valves in the valves 51 will be disclosed in the disclosure dealing with FIG. 3 the control system. Also sharing the common drive with the main switching valve 40 and the control valves 51 is a brake 52 controlled by the system.

On the output 36 of the gas delivery system is a pressure vacuum sensor 55 and a mouthpiece valve56' both connected to the control system. The control system is shown schematically in FIG. 3.

The control system of the present invention utilizes nor fluidic logic elements in conjunction with the control valves synchronously rotated with the main switching valve. The central member of the main switching valve as well as the trigger valve 70, position valve 80, and mouthpiece actuator valve 90 are shown schematically in FIG. 3 with the shaded portion shown of the valves indicative of the duration in time the valves remain open during one complete revolution of the main valve 40.

The control system works in two basic modes, continuous and triggered. In the continuous mode the respiratory rate is determined by the rate at which the main switching valve is rotated. The central member 41 in conjunction with the orifices from tubes 35, 36, 37, and 38 align to supply two complete respiratory cycles per one revolution. In the continuous mode the position valve allows a fluid output for the duration of one complete inspiration and exhalation. The sensors 45 and 46 in conjunction with the mouthpiece valve 90 insure that if the entire tidal volume has not been delivered in one-half the desired respiratory cycle the low tidal alarm will indicate that condition. For the purposes of illustration, the function of the position valve 80 in conjunction with the mouthpiece actuator valve 90 and the diaphragm sensors 45 and 46 will be described for one respiratory cycle. From this description and further descriptions of other control system functions and operations, one skilled in the art can readily understand the operation and design of the disclosed system without the complete description of the system under every possible input condition.

It should be understood that the symbol A means a fluid input; however, each fluidic component receives an input not shown in the schematic diagram in FIG. 3.

The logic elements are shown schematically with a descriptive function adjacent the particular element. While the majority of elements are what are termed nor elements, elements 83 and 104 are what are termed and elements. Regardless of what the elements are called, the function adjacent the element describes its behavior. For example, F=Z+ means there will be an output from that element only if there is neither an input A nor an input B. Similarly where the function is F=Z there will be an output from the element only if the input A is not present. From these examples it should be apparent that where these elements are placed in series the outputs will be alternately present and absent. In contrast to the previous two examples, element 83 defined by the function F=A-B will output only if both inputs A and B are present.

For purposes of illustration it will be assumed that the gas delivery system is in the configuration shown in FIG. 1. Chamber 20 is relatively full of liquid with the gas section 25 of chamber 21 connected by valve 40 to the recipient. As long as valve 90 delivers output but neither sensor 46 nor 45 is closed the output from logic element 82 is present. Valve is synchronized with valve 40 in such a way that it has an output when chamber 21. is delivering a gas volume and the diaphragm stroke limit is monitored by switch 45. When element 82 receives no inputs it will have an output that is conducted to one input of element 83 and also to valve 90. Valve transmits this output from element 83 for one-half of one respiratory cycle (one-fourth of one revolution of the valve 90). This portion of the cycle is intended to be primarily the inhalation of the recipient. During this phase of the respiratory cycle the output from 82 passes through valve 90 to element 86 where the presence of an input prevents 86 from outputting to element 83. Since element 83 will only output and set off the alarm 84 when it has both inputs, the lack of input from element 86 prevents the alarm. However, if switch 45 is not closed in one-half the respiratory cycle element 82 still has an output to element 83. The valve 90, however, closes and prevents the transmission of 82's output to element 86. The lack of an input to element 86 causes it to output to element 83. Element 83 now has two inputs and will output to set off the low tidal volume alarm. It should be apparent that the low tidal volume alarm will be set off when the diaphragm 31 in chamber 21 does not reach its stroke limit (and therefore deliver the intended volume of gas) within the time determined by valve 90.

If switch 45 is closed before valve 90 closes then the input through valve 80 and switch 45 will prevent element 82 from outputting to element 83 and valve 90. The lack of an input from element 82 to element 83 will prevent element 83 from activating the alarm 84. Therefore, if the desired tidal volume is delivered and the switch 45 is closed in the time allotted by valve 90, the alarm 84 will not be activated.

When chamber 20 is to deliver the gas volume the control system works in the same manner since valve 80 does not output during this respiratory cycle, but its lack of input to element 81 produces an output from element 81 that will activate the alarm 84 if switch 46 is not closed by the time valve 90 ceases to transmit the output of element 82 through element 86 to element 83.

The output from valve 90 also controls the mouthpiece valve 56. The valve 56 has an intake configuration and an exhaust configuration with the configuration of the valve determined by elements 87 and 88 but with the recipient able to override the controlled configuration with some small effort.

When the system is delivering a volume of gas (before either switch 45 or 46 is closed) then element 82 has an output to valve 90. Valve 90 will transmit this output for one-half of the desired respiratory cycle (one-fourth of one revolution of valve 90) to elements 86 and 88. Element 88 controls the exhaust or exhalation valve in valve 56 and when it receives an input from valve 90 it will not output and the exhaust valve remains closed. The output from valve 90 negates output from element 86 and, therefore, element 87 outputs and the intake or inhalation valve is open to receive a volume of gas. When an output ceases to be transmitted from valve 90 then the intake valve closes and the exhaust valve is opened. The lack of output from valve 90 can be caused by either switch 45 or 46 closing indicating a complete tidal volume has been delivered (since element 82 no longer outputs) or by valve 90 interrupting output from element 82.

Normally when there is no output to element 88 directly from valve 90 there is no input to element 88 from the sigh timer 91. However, it is desirable at some interval to increase the volume of the inhalation to the recipient above the normal tidal volume. The sigh timer 91 normally gives no input to element 88 therefore leaving control of the exhaust valve to the output from valve 90. The exhaust valve will open only when element 88 gets no input from either valve 90 or sigh timer 91. Therefore, when it is desired to give the recipient a larger volume of gas the sigh timer 91 will give an output to element 88 thereby keeping the exhaust valve closed and the system will then go to the next inhalation phase and give the recipient a double tidal volume. The sigh timer 91 will have a means to vary the elapsed time between such occurrences.

The output of element 86 is also connected to element 92 which triggers a high or low pressure warning when it outputs. The element 92 is prevented from giving an output if any of its three inputs are positive and, therefore, the alarm is prevented from functioning during the exhalation phase of respiration. This is accomplished since during the exhalation phase actuator valve 90 does not output to element 86 and therefore element 86 outputs to both elements 87 and 92. A positive output at 92 prevents its output and therefore allows the alarm to function only to show pressure deviations present on inhalation.

The previously mentioned sigh mode operates to give the recipient a double volume of breathing gas at an interval set by a timer 91. When activated by the sigh timer 91, the output to element 88 prevents the exhaust valve from opening thereby allowing a double inspiration.

The pressure of the gas delivered is monitored in both the continuous and triggered mode by two pressure comparitors 95 and 96. For they case of a low delivery pressure, the variable resistor 93 puts a pressure on the diaphragm in 95. When the pressure is low, element 97 gets an input that prevents 97 from outputting to the element 92. When element 92 does not receive an input it sets off an alarm 115. Similarly when the pressure is too high does not output and 92 again does not have inputs and therefore activates the pressure alarm 115. The alarm level is set for both high and low pressure circuits by the variable pressure regulators 93 and 94.

In the continuous mode the valves rotate continuously since an input is given to element continuously through switch 110. When element 100 receives an input from any of its four inputs, the brake 52 is released and the valves are free to rotate at a rate determined by the motor control 54. In the triggered mode the patient sets the respiratory rate by way of the trigger valve 70 and the vacuum switch 99. The vacuum switch 99 is a variable negative pressure switch preferably having a sensitivity of at least 0.5 mm of 11 0. When the switch is open and the recipient does not attempt to inhale, the valves will rotate until trigger valve 70 outputs at either of its output positions apart to element 101 that will reverse output to element 100. Element 100 that controls the brake 52 will apply the brake when it receives no output from element 101. The valves 51 will not rotate until a positive input is received at element 100. Such an input would be caused by the momentary closing of switch 99 by an attempt of the recipient to inhale. In the absence of such an attempt, element 101 will output to the adjustable timer 105 which allows the output to be transmitted for a set time. At the end of that set time it stops the output and if the switch 99 is still open element 103 will have two negative inputs and will output to element 104 as well as to timer 106. Timer 106 will transmit the output to element 100 which will initiate continuous operation until timer 106 ceases its output and the system will again wait a time set by timer 105 for the recipient to attempt inhalation. The system will again go into the continuous mode if there .is no closure of switch 99 within the time set on timer 105. The apnea alarm will be actuated when both the output from timer 106 and element 103 are input to element 104. Both timer 105 and 106 are self-resetting and will revert back to the transmission of any inputs to the timers after the momentary interruption at the end of their set time. The timers used for such an application should preferably have an adjustable set time of from zero to 30 seconds.

The present invention has been described by illustrations of a system utilizing fluid logic components and it should be understood that while fluidic logic elements are particularly suited for this system, the logic of the system may be carried out electrically with the valves described being analogous to switches and the logic elements being electrical having the same logic function as shown adjacent the fluid logic elements. It should also be understood that the logic functions disclosed can be developed using multiple elements in combinations having different logic functions individually but combining to yield the logic function disclosed. The concept of the invention is limited only by the appended claims.

We claim:

I. An apparatus for the delivery of accurately portioned volumes of gas comprising:

a. two chambers;

b. separating means within said chambers disposed to divide each of said chambers into two sections;

c. first connecting means allowing communication of a liquid in one section of one chamber with a liquid section in the second chamber;

d. a volume of liquid within the two communicating sections less than the total volume of the two chambers;

e. a flow regulator in said first connecting means;

f. second connecting means from two gas-containing sections to a valve; and

g. a valve disposed to alternately connect one gascontaining section of a chamber with a pressurized gas source while the opposite gas-containing section is connected to a gas-delivery system thereby delivering discrete quantities of said gas at a rate determined by said flow regulator and equal in volume to the amount of liquid alternately displaced from one liquid section to the other.

2. The apparatus of claim 1 wherein said valve is a rotary valve comprised of:

a. a valve body having orifices therein with said orifices leading respectively to a source of pressurized gas, the gas-containing section of a first chamber, the gas-containing section of the second chamber and the gas-delivery system; and

b. a rotating member within said valve body having at least two reliefs disposed to uncover pairs of said orifices as said member rotates.

3. The apparatus of claim 1 wherein said separating means are diaphragms.

4. The apparatus of claim 1 where said first connecting means includes a valve for the removal of liquid from the liquid-filled sections of said chambers.

5. The apparatus of claim 2 wherein said rotary valve also contains sections separate from the switching section with said separate sections for communicating with a control system of a respirator system and for supplying information to said control system in relation to the position of the rotating member in the switching section of said valve.

6. The apparatus of claim 3 wherein the position of the diaphragms is detected at the extremities of displacement by s ensors proximate to said chambers.

Claims (6)

1. An apparatus for the delivery of accurately portioned volumes of gas comprising: a. two chambers; b. separating means within said chambers disposed to divide each of said chambers into two sections; c. first connecting means allowing communication of a liquid in one section of one chamber with a liquid section in the second chamber; d. a volume of liquid within the two communicating sections less than the total volume of the two chambers; e. a flow regulator in said first connecting means; f. second connecting means from two gas-containing sections to a valve; and g. a valve disposed to alternately connect one gas-containing section of a chamber with a pressurized gas source while the opposite gas-containing section is connected to a gas-delivery system thereby delivering discrete quantities of said gas at a rate determined by said flow regulator and equal in volume to the amount of liquid alternately displaced from one liquid section to the other.

2. The apparatus of claim 1 wherein said valve is a rotary valve comprised of: a. a valve body having orifices therein with said orifices leading respectively to a source of pressurized gas, the gas-containing section of a first chamber, the gas-containing section of the second chamber and the gas-delivery system; and b. a rotating member within said valve body having at least two reliefs disposed to uncover pairs of said orifices as said member rotates.

3. The apparatus of claim 1 wherein said separating means are diaphragms.

4. The apparatus of claim 1 where said first connecting means includes a valve for the removal of liquid from the liquid-filled sections of said chambers.

5. The apparatus of claim 2 wherein said rotary valve also contains sections separate from the switching section with said separate sections for communicating with a control system of a respirator system and for supplying information to said control system in relation to the position of the rotating member in the switching section of said valve.

6. The apparatus of claim 3 wherein the position of the diaphragms is detected at the extremities of displacement by sensors proximate to said chambers.

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