CLOSED CIRCUIT MEDICAL RESPIRATORS

• US 3,695,263 A
• Filed: 01/29/1970
• Issued: 10/03/1972
• Est. Priority Date: 01/30/1969
• Status: Expired due to Term

• Current Assignee: Honeywell BV Rijswijkstraat
• Original Assignee: Barry John Kipling
• Inventors: Kipling, Barry John
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Mitchell, J. B.
• Application Number:
  US05/006,845
• Time in Patent Office: 978 Days
• Field of Search: 128/145.6,145R,145.7,145.5,DIG.17,146,146.4,146.5,142-142.3
• US Class Current: 128/204.24
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0009 with sub-atmospheric pressure, e.g. during expiration
• CPC Class Codes: A61M 16/0075 Bellows-type
• CPC Class Codes: A61M 2016/0024 with an on-off output signal, e.g. from a switch

Abstract

A closed circuit medical respirator provided with a face mask for applying patient gas to a patient and for transmitting exhaled gas to the respirator. A closed path extends from the face mask to a gas purifier, a bellows and back to the face mask. Appropriate drive means are connected with the bellows for causing flow of gas to and from the patient so as to create a positive pressure in the path during one part of the respiratory cycle and a negative pressure during the other part. A gas flow sensor is provided in the path and is connected to a controller for operating the drive means of the bellows. Changeover switches connected with a multi-vibrator are provided for connection with the controller and inspiratory and expiratory valves so as to alternately operate the flow of gas in accordance with the required respiratory cycle.

Claims

1. A closed circuit medical respirator comprising a face mask for applying patient gas to a patient, an expiratory valve within said face mask and having an inlet port and an outlet port, a gas purifier having an inlet and an outlet connected on the inlet side thereof to the outlet port of said expiratory valve, a gas container connected to the outlet of said gas purifier, said container being connected to said inlet port of said expiratory valve to thereby complete a closed path, a source of patient gas to replenish losses in the system connected to said path, sensor which produces an outlet signal in response to a predetermined fluidic property connected with said path at a point between said expiratory valve and said gas purifier, a bias control means conNected to said sensor, a source of driving gas connected to said bias control, a controller connected to and operated by the output signal of said sensor, a driving means linked to said container for driving same, a source of driving gas connected to said controller so as to be passed therethrough and connected to said driving means, a pneumatic timing circuit operated by a source of driving gas connected thereto, and a pair of changeover valves connected to said timing circuit and operated thereby so as to alternately provide a source of driving gas to the driving means operating the flow of gas from said container in accordance with the required respiratory cycle, said sensor operating to vary the amount of driving gas allowed to pass through said controller as determined by the phase of the respiratory cycle.

2. The closed circuit medical respirator according to claim 1 wherein said container comprises an expandable bellows.

3. The closed circuit medical respirator according to claim 2 further comprising a first non-return valve located in said closed path between the outlet port of said expiratory valve and the inlet of said gas purifier, a second non-return valve located in said closed path between the outlet of said gas purifier and said bellows, and a third non-return valve located in said closed path between said bellows and the inlet port of said expiratory valve, said non-return valves being provided so as to prevent circulation of gas in the wrong direction.

4. The closed circuit medical respirator according to claim 3 wherein said source of patient gas for replenishing losses is substantially at atmospheric pressure and is connected directly to said path at a point between said second non-return valve and the outlet of said gas purifier.

5. The closed circuit medical respirator according to claim 3 further comprising an inspiratory valve having the source of patient gas for replacing losses connected thereto, said inspiratory valve being connected to said closed path at a point between said second non-return valve and the outlet of said gas purifier.

6. The closed circuit medical respirator according to claim 5 further comprising a first actuating cylinder for said expiratory valve and a second actuating cylinder for said inspiratory valve, said actuating cylinders being connected through one of said changeover valves to a source of driving gas so as to be alternately energized in accordance with the required respiratory cycle.

7. The closed circuit medical respirator according to claim 6 further comprising an amplifier connected between the output of said sensor and said controller.

8. The closed circuit medical respirator according to claim 7 wherein said sensor is a differential pressure operated valve.

9. A closed circuit medical respirator comprising a flexible bellows forming a gas container for receiving and supplying gas to a patient, means for coupling said container to a patient, a driving means connected to said container for operating the flow of gas therefrom, said driving means comprising a piston within a cylinder connected to the container, a sensing means connected between said coupling means and said container, said sensing means having adjustable bias means applied thereto and output means controllable by the level of said bias, controller means for controlling said driving means so that the difference between the flow of gas as determined by said driving means and a flow of gas from said patient is substantially constant, a piston rod connected between said piston and said bellows so that movement of the piston within the cylinder produces a change of volume within the bellows thereby controlling the flow of gas to and from the patient, and a source of driving gas connected to the cylinder for operating same, said output means of said sensing means being connected to said controller means so as to control the pressure of gas passing therethrough, said sensing means being arranged to detect said difference between flow raTes and said difference being controlled by the bias applied to the sensor.

10. The closed circuit medical respirator according to claim 9 further comprising first and second changeover valves connected to said expiratory and said inspiratory valves and to said means for controlling said driving means and said cylinder respectively for controlling movement of the piston within the cylinder in alternate directions in accordance with the respective periods of the respiratory cycle, and a fluid operated multi-vibrator having a source of driving gas connected thereto, said multi-vibrator being connected to said first and second changeover switches.

11. The closed circuit medical respirator according to claim 10 wherein said means for controlling said driving means comprises a controller device connected between said sensing means and said piston carrying cylinder, a source of driving gas and means connected between said source of driving gas and said controller for passing driving gas therethrough to the cylinder, whereby said sensor controls the amount of driving gas passed by said controller to said cylinder.

12. The closed circuit medical respirator according to claim 11 further comprising an amplifier connected between the output of said sensing means and said controller for amplifying the output signal to the controller so that said controller controls the pressure of the drive gas fed to the cylinder.

13. The closed circuit medical respirator according to claim 12 wherein said means for coupling said supply of gas to a patient is a face mask having housed therein a respiratory valve controlled by alternate operation of said multi-vibrator so that the respiratory valve allows patient gas to flow from the bellows via one part of the closed circuit to the face mask during each inspiratory period of the respiratory cycle and from the face mask back to the bellows via the other part of the closed circuit during each expiratory period.