Importance

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Abstract

A ventilator for inducing or assisting lung function in humans is characterized by a control system that provides for semi-automatic operation in which a single complete ventilation cycle in accordance with predetermined ventilation parameters (tidal volume, durations of inhalation and exhalation phases) is initiated by operation of a trigger. The ventilator is particularly useful in one-man resuscitation by CPR. The control system may require a discrete trigger operation to initiate each successive ventilation cycle or it may provide for continuous operation with timed successive cycles, in the manner of an automatic ventilator, by holding or latching the trigger. Various embodiments based on gas-powered ventilators are disclosed but the invention is also applicable to electrically operated or controlled ventilators. In a typical embodiment (FIG. 1) the output line (6) of a pneumatic oscillator is controlled by a diaphragm (22) held closed by a spring (36) loaded by a trigger (31) that when operated relieves the spring load and permits the diaphragm to open the output line. The output line pressure then acts on the diaphragm to hold the output line open until output pressure falls at the termination of the inhalation cycle, whether or not the trigger is released before that instant.

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First Claim