Lung ventilators

• US 4,206,754 A
• Filed: 05/24/1977
• Issued: 06/10/1980
• Est. Priority Date: 06/02/1976
• Status: Expired due to Term

• Current Assignee: BOC Limited (Linde Plc)
• Original Assignee: BOC Limited (Linde Plc)
• Inventors: Cox, Lawrence A., Smethers, John D.
• Primary Examiner(s): Recla, Henry J.
• Application Number:
  US05/799,985
• Time in Patent Office: 1,113 Days
• Field of Search: 128/145.8, 128/145.6, 128/145.5, 128/188, 128/142.2
• US Class Current: 128/204.21
• CPC Class Codes: A61M 16/0012 by Venturi means
• 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: A61M 2016/0039 in the inspiratory circuit

Abstract

A volume-cycled lung ventilator providing for both spontaneous breathing of a patient and intermittent mandatory ventilation, the invention provides two parallel inspiratory flow paths, one flow path including a demand valve for supplying gas to the patient during spontaneous breathing and the other flow path including a solenoid-operated inspiratory flow valve for providing intermittent mandatory breaths. The invention provides structure capable of adjusting the intervals between mandatory breaths, the volume of each such breath and the flow waveform of each such breath. An expiratory flow path including a fluid operated expiratory flow valve is further provided. A flow rate signal generator in the expiratory flow path acts to sense the rate of exhalation of the patient and is effective to inhibit the opening of the inspiratory flow valve unless the rate of exhalation is below a predetermined value.

Claims

1. A volume-cycled lung ventilator providing for both spontaneous breathing of a patient connected thereto and intermittent mandatory ventilation, the ventilator comprising:

means defining a first inspiratory flow path and means connecting such flow path at its inlet end to a source of pressurized respirable gas;

means defining a second inspiratory flow path and means connecting such flow path at its inlet end to the source of respirable gas;

means defining an expiratory flow path connected at its outlet end to atmosphere;

patient connection means for supplying respirable gas from the outlet ends of said first and second inspiratory flow paths to a patient, and for supplying gas expired by the patient to the inlet end of said expiratory flow path;

a normally-closed inspiratory flow valve in said first inspiratory flow path and a normally-open expiratory flow valve in said expiratory flow path;

means for operating said inspiratory and expiratory flow valves in synchronization at preselectable intervals to provide intermittent mandatory inspiration through said first inspiratory flow path and expiration through said expiratory flow path, the inspiratory flow valve being open during the inspiratory phase and the expiratory flow valve being closed during the inspiratory phase, the inspiratory flow valve being closed during the expiratory phase and the expiratory flow valve being open during the expiratory phase;

valve means in said second inspiratory flow path to permit spontaneous inspiration through such flow path while expiration is occurring through said expiratory flow path, the valve means comprising a demand valve adapted to permit gas to flow through the second inspiratory flow path from the source to the patient at a flow rate determined by the inspiratory effort of the patient, and a second expiratory valve being provided in said expiratory flow path downstream of said normally open expiratory valve and said demand valve and second expiratory valve are fluid-biased valves and include a regulator connected to the demand valve and second expiratory valve for adjustably biasing both the demand valve and the fluid-biased second expiratory valve so that the expiratory pressure required to stop the supply of gas by the demand valve to the patient is maintained substantially the same as the pressure required to open the second expiratory valve; and

,

means for inhibiting the opening of said inspiratory flow valve if the patient is expiring gas at a flow rate above a chosen value, the inhibiting means comprising signal generating means in said expiratory flow path for producing signals representative of the rate of flow of gas expired through said flow path, and means responsive to said signals for inhibiting the opening of said inspiratory flow valve during the exhalation phase.

2. A lung ventilator as claimed in claim 1 wherein means sensitive to pressure in the outlet end of the first inspiratory flow path are effective to close said inspiratory flow valve when said pressure reaches a preset maximum.