Volume-rate respirator system and method

• US 3,905,362 A
• Filed: 10/02/1973
• Issued: 09/16/1975
• Est. Priority Date: 10/02/1973
• Status: Expired due to Term

• Current Assignee: Allied Healthcare Products Incorporated
• Original Assignee: Allen C. Brown, Neil R. Hattes, Theodore B. Eyrick
• Inventors: Hattes, Neil R., Brown, Allen C., Eyrick, Theodore B.
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Recla, Henry J.
• Application Number:
  US05/402,677
• Time in Patent Office: 714 Days
• Field of Search: 128/142,145,145.5,145.6,145.7,145.8,188 222/3 417/328,392,395 185/4,27
• US Class Current: 128/202.22
• CPC Class Codes: A61M 16/0012 by Venturi means
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0072 Tidal volume piston pumps
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/0841 for sampling
• CPC Class Codes: A61M 16/1055 bacterial
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/1025 the O2 concentration

Abstract

A respiration unit for supplying a preselected limited volume of breathing gas to a patient at limited positive pressures, and at a preselected limited flow rate is disclosed. The system includes an air delivery cylinder having a drive weight which is free to move up and down. A diaphragm connected to the weight divides the cylinder into an upper control chamber and a lower delivery chamber. A vacuum source is connected to the control chamber through a first solenoid-controlled valve to regulate the lifting of the weight, and a second solenoid-controlled valve regulates the bleeding of air into the control chamber to release and regulate the rate of fall of the weight, thereby driving breathing gas under pressure out of the lower chamber. A control system regulates the lift and lower cycles of the drive weight to provide the required operation of the system, with various sensors being provided to allow patient control of the system under selected conditions, and to assure patient safety. The control system incorporates, among other things, means for providing a variable inspiratory-expiratory ratio, for permitting patient assisted breathing, for mixing oxygen with air or anesthetic gases, for periodically altering the breathing pattern, for permitting selection of positive or negative end expiratory pressure, for allowing selection of the breathing waveform, and for providing accurate displays of essential parameters.

Claims

1. In a respirator system, a breathing gas delivery cylinder including a housing and piston means dividing said housing into an upper control chamber and a lower delivery chamber;

means for producing a vacuum in said control chamber for lifting said piston means to expand said delivery chamber;

means for releasing said vacuum to lower said piston means and thereby compress said delivery chamber;

control means for periodically and alternately energizing said vacuum producing means and said vacuum releasing means for drawing breathing gas into said delivery chamber and for discharging said breathing gas;

delivery means connected to said discharge means for directing said breathing gas to a patient.

2. The system of claim 1, wherein said delivery means comprises a patient breathing manifold, and conduit means connecting said discharge means to said manifold.

3. The system of claim 2, said delivery means further including valve means in said conduit means for restricting the direction of flow of said breathing gas in a direction toward said manifold.

4. The system of claim 2, wherein said manifold includes outlet means for receiving exhaled breathing gas from said patient, and selectively operable valve means in said outlet means for controlling the exhalation of said gas.

5. The system of claim 4, wherein said selectively operable valve means in said outlet includes a solenoid-operated expiratory valve.

6. The system of claim 5, wherein said selectively operable valve means in said outlet includes a balloon valve adapted to open and close said outlet means, and a solenoid-operated expiratory control valve selectively operable to expand said balloon valve to close said outlet means to prevent exhalation by said patient and open said outlet means to permit exhalation by said patient.

7. The system of claim 6, further including a source of pressurized gas for said balloon valve, said expiratory control valve being operable to connect said balloon valve to said source of pressurized gas to expand said balloon.

8. The system of claim 6, further including expiratory assist means for producing a pressure reduction in said outlet means for aiding patient exhalation.

9. The system of claim 8, wherein said expiratory assist means comprises a source of pressurized gas, Venturi means, a solenoid-operated expiratory assist valve conencting said source of pressurized gas to said Venturi to provide a source of negative pressure, and means for connecting said source of negative pressure to said outlet means to produce said pressure reduction therein.

10. The system of claim 9, wHerein said means for producing a vacuum in said control chamber comprises a source of vacuum, and lift valve means selectively operable to connect said vacuum source to said control chamber.

11. The system of claim 10, wherein said lift valve means is a solenoid-operated valve, said control means periodically operating said solenoid valve to lift said piston.

12. The system of claim 9, wherein said means for releasing said vacuum comprises solenoid-operated bleeder valve means connected to said control chamber and periodically energized by said control means to allow said piston to compress said delivery chamber.

13. The system of claim 12, wherein said means for releasing said vacuum further includes a variable rate orifice for limiting the rate at which said vacuum is released.

14. The system of claim 13, wherein said means for producing a vacuum in said control chamber comprises a source of vacuum and solenoid-controlled lift valve means operable by said control means for connecting said source of vacuum to said control chamber.

15. The system of claim 14, further including inlet means for supplying at least a first fluid to said cylinder, and mixing means for selectively supplying to said inlet means a second fluid at a controlled rate.

16. The system of claim 15, wherein said mixing means comprises a pressurized source of said second fluid and variable orifice means connecting said source to said inlet means, said variable orifice means limiting the rate at which said second fluid is supplied to said inlet.

17. The system of claim 16, wherein said mixing means further includes solenoid control valve means between said source and said inlet means and energizable by said control means to allow said second fluid to be supplied to said inlet.

18. The system of claim 17, wherein said control means is operative to supply said second fluid to said inlet only during lifting of said piston.

19. The system of claim 18, wherein said first fluid is air and said second fluid is oxygen.

20. In a respirator system for delivering at limited positive pressures a limited volume of breathing gas at a limited flow rate, a breathing gas delivery cylinder including a housing and piston means dividing said housing into an upper control chamber and a lower delivery chamber;

a source of vacuum;

a solenoid-controlled lift valve operable to connect said vacuum source to said control chamber to lift said piston and expand said delivery chamber;

means for admitting a breathing gas into said delivery chamber upon expansion of said delivery chamber;

solenoid-controlled lower valve means connected to said control chamber and operable to admit air at atmospheric pressure into said control chamber to lower said piston whereby the weight of said piston will compress said delivery chamber to discharge said breathing gas;

means for controlling the flow of atmospheric air into said control chamber to limit the lowering rate of said piston;

outlet means connected to said delivery chamber for receiving breathing gas discharged from said delivery chamber when said piston is lowered; and

delivery means connected to said outlet means for directing said discharged breathing gas to a patient.

21. The system of claim 20, wherein said delivery means further includes:

a patient breathing manifold, said manifold having means for directing said breathing gas to said patient and for receiving breathing gas exhaled by said patient; and

a solenoid-controlled expiration valve for opening said manifold means to permit exhalation by said patient.

22. The system of claim 21, further including a solenoid-controlled expiratory assist valve for producing in said manifold means a reduction in pressure for aiding patient exhalation.

23. The system of claim 22, further including control means for periodically activating said lift valve and said lower valve for drawing said breathing gas into said delivery chamber during lifting aNd for discharging said breathing gas during lowering of said piston.

24. The system of claim 25, wherein said control means includes circuit means energizable in an inspiratory mode to operate said lower valve means to lower said piston to deliver breathing gas to said patient, and energizable in an expiratory mode to operate said expiration valve to permit said patient to exhale.

25. The system of claim 24 wherein said control means further includes circuit means energizable in a hold mode to prevent said control means from operating in either an inspiratory or expiratory mode.

26. The system of claim 25, further including breathing cycle control means for selectively operating said inspiratory mode circuit means, said expiratory mode circuit means, and said hold mode circuit means in timed sequence to provide an adjustable breathing waveform.

27. The system of claim 26, wherein said breathing cycle control means includes rate control timer means for producing a train of normal rate control pulses, and execute cycle pulsing means responsive to said normal rate control pulses to initiate a breathing cycle by energizing said circuit means in said inspiratory mode.

28. The system of claim 27 further including inflation hold control means responsive to the termination of said inspiration mode to initiate a hold mode.

29. The system of claim 28, further including inspiration timer means responsive to the termination of said inspiration and said hold modes to initiate said expiratory mode;

said expiratory mode being terminated by the initiation of the next following inspiration mode.

30. The system of claim 23, wherein said control means includes means for selecting a desired volume of breathing gas for delivery to a patient and means for activating said lift valve when said delivery chamber contains less than said selected volume, whereby said piston is raised in said cylinder.

31. The system of claim 30, wherein said means for activating said lift valve comprises cylinder volume control means for comparing the actual cylinder volume with said selected volume, and means for inhibiting said lift valve during the discharge of gas from said delivery chamber.

32. The system of claim 23, further including inlet pressure sensing means responsive to the pressure of the breathing gas drawn into said delivery chamber, and alarm means responsive to said inlet pressure sensing means.

33. The system of claim 32, further including low manifold pressure sensing means and alarm means responsive to low manifold pressures.

34. The system of claim 33, further including cycle sensing means for monitoring the cycling of said respirator, and alarm means responsive to improper cycling.

35. The system of claim 34, further including ratio error detecting means responsive to the ratio of inspiration time to expiration time.

36. The system of claim 23, further including adjustable pressure limiter means responsive to the pressure of the breathing gas in said manifold for terminating the delivery of breathing gas to said patient.

37. The system of claim 22 further including normal breathing cycle control means incorporating an adjustable rate control timer for producing a train of normal rate control pulses having a selectable repetition rate, and execute cycle pulsing means responsive to said rate control pulses for periodically activating said lower valve to initiate an inhalation mode in a normal patient breathing cycle.

38. The system of claim 37, wherein said normal breathing cycle control means further includes inflation hold control means responsive to the termination of an inhalation mode to initiate a hold mode in the patient breathing cycle.

39. The system of claim 38, wherein said normal breathing cycle control means includes inspiration timer means responsive to the termination of said inspiration and hold modes to activate said solenoid-controlled expiration valve to initiate an expiration mode in the patient breathing cycle.

40. The system of claim 39 wherein the duration of each of said inspiration, hold, and expiration modes is selectable to produce a predetermined timed relationship between said modes, whereby an adjustable normal breathing waveform is provided by the respiratory system.

41. The system of claim 37 further including automatic sigh control means for periodically overriding said normal breathing cycle control means.

42. The system of claim 37, further including error detection means for overriding said normal breathing cycle control means in the event of malfunction in said system.

43. The system of claim 37, further including manual sigh control means for manually overriding said normal breathing cycle control means to produce a sigh function.

44. The system of claim 37 further including manual breath control means for overriding said normal breathing cycle control means to initiate an inspiration mode.

45. The system of claim 37, further including volume delay means for preventing the initiation of an inspiration mode until breathing gas is available in said delivery chamber.

46. The system of claim 45, further including manually operable sigh and breath control means for overriding said normal breathing cycle control means to enable the machine operator to initiate an inspiration mode.

47. The system of claim 46, further including inhibit means for preventing manual initiation of an inhalation mode during an existing inhalation mode.

48. The system of claim 41, further including first adjustable pressure limiter means responsive to the normal pressure of the breathing gas in said manifold and second adjustable pressure limiter means responsive to the sigh pressure of the breathing gas in said manifold, said first and second pressure limiter means being operative to terminate the delivery of breathing gas to said patient.

49. The system of claim 37, further including breath assist control means responsive to patient breathing efforts to override said normal breathing cycle control means initiate an inspiration mode, said assist control means incorporating sensitivity adjustment means to vary the amount of patient effort required to initiate said inspiration mode.

50. The system of claim 37, wherein said normal breathing cycle control means further includes inspiration timer means responsive to the termination of said inspiration mode to activate said solenoid-controlled expiration valve to initiate an expiration mode in the normal patient breathing cycle.

51. The system of claim 50, further including pressure responsive control means for modulating the operation of said expiration valve to maintain a preselected positive end expiration pressure in said manifold means.

52. The system of claim 50, further including pressure responsive control means for activating said solenoid-controlled expiratory assist valve for producing in said manifold means a preselected negative end expiratory pressure.