Lung ventilator
First Claim
1. An improved lung ventilator for use in weaning a patient from dependence thereupon comprising inlet means for connection to a source of respirable gas, outlet means for supplying respirable gas to a patient, said inlet means and outlet means forming part of an inspiratory flow path for the respiratory gas, valve means for controlling the flow of respiratory gas in the flow path for spontaneous breathing cycles, exhalation conduit means through which pass the gases exhaled by a patient during the exhalation phase of each respiratory cycle, means bypassing said valve means for providing an automatic ventilation cycle for assisted breathing;
- the improvement comprising means adapted to produce a first signal representing the rate of flow of gas passing through said conduit during each exhalation phase;
means adapted to provide a second signal representing the minute volume of exhaled gases through said conduit; and
means responsive to said signals for triggering the start of said automatic ventilation cycle when, in any given ventilation phase, the minute volume of exhaled gases is below a chosen threshold and the rate of flow of the exhaled gases has virtually decreased to zero.
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Abstract
A lung ventilator particularly adapted for use in weaning patients from dependence thereupon and includes an exhalation conduit through which the gas exhaled by the patient is passed. Both the rate of flow of gas passing through the exhalation conduit during each individual exhalation phase, and the minute volume of exhaled gases are monitored. If, during any given exhalation phase, the minute volume of exhaled gases should fall below a chosen threshold, indicating that the patient fails to breathe adequately, the ventilator is triggered to perform a mandatory ventilation cycle. The ventilator is inhibited from delivering mandatory breaths, however, until the rate of flow of exhaled gas in a given exhalation phase has reduced to the point which indicates that exhalation has ceased.
127 Citations
4 Claims
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1. An improved lung ventilator for use in weaning a patient from dependence thereupon comprising inlet means for connection to a source of respirable gas, outlet means for supplying respirable gas to a patient, said inlet means and outlet means forming part of an inspiratory flow path for the respiratory gas, valve means for controlling the flow of respiratory gas in the flow path for spontaneous breathing cycles, exhalation conduit means through which pass the gases exhaled by a patient during the exhalation phase of each respiratory cycle, means bypassing said valve means for providing an automatic ventilation cycle for assisted breathing;
- the improvement comprising means adapted to produce a first signal representing the rate of flow of gas passing through said conduit during each exhalation phase;
means adapted to provide a second signal representing the minute volume of exhaled gases through said conduit; and
means responsive to said signals for triggering the start of said automatic ventilation cycle when, in any given ventilation phase, the minute volume of exhaled gases is below a chosen threshold and the rate of flow of the exhaled gases has virtually decreased to zero. - View Dependent Claims (2, 3, 4)
- the improvement comprising means adapted to produce a first signal representing the rate of flow of gas passing through said conduit during each exhalation phase;
Specification