Ventilator control system and method
First Claim
1. A method of compensating for the gas flow resistance in a ventilatory apparatus, the method comprising the steps of:
- (a) determining the peak exhalation flow rate;
(b) determining the airway resistance;
(c) calculating the effective airway pressure in response to the peak exhalation flow rate and the airway resistance; and
(d) applying a negative airway pressure to an exhalation circuit such that the effective circuit pressure is greater than zero and less than PEEP.
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Accused Products
Abstract
The invention features an exhalation assist device for adjusting the airway resistance in an exhalation circuit of a medical ventilator. The device includes a set of pressure, airflow and airway sensors, a controlling processor, a user interface, and a ventilatory unit in communication with a medical ventilator. Data relating to pressure within the ventilatory unit and data relating to exhalation airflow, exhalation circuit pressure and exhalation circuit resistance are provided to the controlling processor by the sensors. The controlling processor compares measured and calculated values for airway pressure, airflow, airway resistance and applied negative pressure with desired values that have been entered by a clinician. Based on these calculations, the controlling processor transmits a signal that will change the applied negative pressure applied to the exhalation circuit by the ventilatory unit. The amount of negative pressure applied during the breathing cycle is varied by the controlling processor so that the amount of exhalation assist increases proportionately with the amount of exhalation flow and so that the amount of pressure within the patient airway remains constant at a level greater than zero and less than PEEP.
307 Citations
10 Claims
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1. A method of compensating for the gas flow resistance in a ventilatory apparatus, the method comprising the steps of:
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(a) determining the peak exhalation flow rate; (b) determining the airway resistance; (c) calculating the effective airway pressure in response to the peak exhalation flow rate and the airway resistance; and (d) applying a negative airway pressure to an exhalation circuit such that the effective circuit pressure is greater than zero and less than PEEP. - View Dependent Claims (2, 3, 4)
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5. A ventilator assist device comprising:
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a reservoir for inhaled and exhaled gas in communication with a breathing apparatus adapted for attachment to a patient; a source of negative pressure in communication with said reservoir; an exhalation flowmeter in communication with said breathing apparatus; a flow resistance sensor in communication with said breathing apparatus; a data processing unit in electrical communication with said negative pressure source and also in electrical communication with said exhalation flowmeter and said circuit resistance sensor; and a user interface in electrical communication with said negative pressure source, wherein said exhalation flowmeter measures a peak exhalation flow rate, said circuit resistance sensor measures an airway resistance, and said data processing unit calculates an effective airway pressure from said measured peak exhalation flow rate and said airway resistance, and wherein said user interface allows direct setting of a value for desired negative airway pressure greater than zero and less than PEEP by a user. - View Dependent Claims (6, 7, 8, 9, 10)
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Specification