VENTILATORS

• US 3,768,468 A
• Filed: 01/18/1971
• Issued: 10/30/1973
• Est. Priority Date: 01/21/1970
• Status: Expired due to Term

• Current Assignee: Lawrence Alfred Cox
• Original Assignee: Lawrence Alfred Cox
• Inventors: Cox, Lawrence Alfred
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Dunne, G. F.
• Application Number:
  US05/106,960
• Time in Patent Office: 1,016 Days
• Field of Search: 128/145.8,142-142.3,142.4,145R,145.5,145.6,145.7,188,DIG.17 137/68R
• US Class Current: 128/204.21
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: Y10S 137/908 Respirator control

Abstract

A lung ventilator in which the volume of respirable gas passing to the patient per unit time is continuously measured and the flow stopped, to mark the end of the inspiratory phase and the start of the expiratory phase, when a chosen volume has passed through the meter.

Claims

1. A lung ventilator adapted to control the volume of respirable gas supplied to a patient irrespective of the duration of the inspiratory phase of the patient'"'"''"'"'s respiratory cycle, of the patient'"'"''"'"'s airway pressure, or of variations in the rate at which gas flows to the patient, including an inhalation passageway connected at one end to a supply of pressurized respirable gas, and at the other end to the patient;

an exhalation passageway connected to the patient;

a gas flow control valve in said inhalation passageway;

a gas flow sensitive transducer in said inhalation passageway and said exhalation passageway adapted to generate signals of which the frequency is proportional to the gas flow rate;

means integrating said flow rate signals to produce a signal which is a measure of the volume of gas flowing therethrough;

means for closing the said valve when the said integrated signal from said gas flow sensitive transducer in said inhalation passageway reaches a chosen value, and means for reopening the valve and rendering the transducer effective at the beginning of the next inspiratory phase.

2. A lung ventilator as claimed in claim 1, including a two-position, multiple-port valve movable between a '"'"''"'"'manual'"'"''"'"' and an '"'"''"'"'automatic'"'"''"'"' position, the valve having two of its ports connected to the inspiration and expiration passageways of the ventilator, two ports adapted to be connected to a patient, and the remaining port or ports adapted to be connected to a manual rebreathing device.

3. A lung ventilator as claimed in claim 2, in which the said multiple-port valve is connected to means for displacing it into the manual position when the pressure of oxygen or other selected gas supplied to the ventilator falls below a chosen minimum value.

4. A lung ventilator as claimed in claim 1, in which the signals corresponding to the inspiratory volume flow are fed to an integrator of which the output is fed to a comparator for comparison with like signals corresponding to the desired volume flow, equalisation of the two signals being effective to cause the comparator to generate a changeover signal stopping the inspiratory flow and allowing the expiratory flow to start.

5. A lung ventilator as claimed in claim 4, in which the outlet of the comparator is connected to a device controlling both a valve in the inspiratory flow passageway and aN auxiliary valve controlling the position of a valve in the expiratory flow passageway.

6. A lung ventilator as claimed in claim 4, in which operation of the control device is adapted to start a timer when the comparator generates the said changeover signal and which, after a chosen time has elapsed, causes the comparator to be reset and the inspiratory valve to be opened.

7. A lung ventilator as claimed in claim 1, including a minute volume indicator connected to said exhalation integrating means.

8. A lung ventilator as claimed in claim 7, in which connected to the minute volume indicator is an alarm device adapted to operate when the minute volume goes beyond chosen minimum and maximum values.

9. A lung ventilator as claimed in claim 4, including a tidal volume indicator connected to the inspiratory flow integrator.

10. A lung ventilator as claimed in claim 1, in which couplied to the inspiratory flow passageway is a meter for indicating the oxygen content of the gas supplied to the outlet of the ventilator.