Closed loop control system for a high frequency oscillation ventilator
First Claim
1. A closed loop method of regulating piston movement of a piston and mean airway pressure (MAP) in a patient ventilator system having an exhalation valve, the method comprising the steps of:
- measuring a pressure at the patient and generating a measured pressure signal in response thereto;
comparing a desired oscillator pressure signal to the measured pressure signal and generating a pressure output signal in response thereto;
measuring piston displacement with respect to a midpoint of full stroke of said piston and generating a piston displacement signal in response thereto;
subtracting the piston displacement signal from zero as a desired piston position and generating a displacement output signal in response thereto;
combining the pressure output signal with the displacement output signal and generating an oscillator command signal in response thereto for regulating the piston movement;
comparing a desired MAP signal to the measured pressure and generating an exhalation valve command signal in response thereto for regulating MAP at the patient; and
centering said piston about said midpoint of full stroke of said piston while regulating MAP.
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Accused Products
Abstract
A control system for a high frequency oscillating ventilator (HFOV) includes an oscillator controller and a mean airway pressure (MAP) controller. The HFOV includes a reciprocating piston which is adapted to generate positive and negative pressure waves for delivery to a patient airway. The oscillator controller comprises a pair of closed loop control circuits including an oscillator pressure loop and a centering loop which are collectively adapted to regulate frequency and amplitude of piston reciprocations and centering of the piston. The MAP controller comprises a closed loop control circuit that is adapted for regulating MAP at the patient utilizing feedback in the form of patient circuit pressure. Likewise, the oscillator controller utilizes patient circuit pressure as well as piston displacement feedback in order to regulate movement of the piston.
53 Citations
8 Claims
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1. A closed loop method of regulating piston movement of a piston and mean airway pressure (MAP) in a patient ventilator system having an exhalation valve, the method comprising the steps of:
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measuring a pressure at the patient and generating a measured pressure signal in response thereto; comparing a desired oscillator pressure signal to the measured pressure signal and generating a pressure output signal in response thereto; measuring piston displacement with respect to a midpoint of full stroke of said piston and generating a piston displacement signal in response thereto; subtracting the piston displacement signal from zero as a desired piston position and generating a displacement output signal in response thereto; combining the pressure output signal with the displacement output signal and generating an oscillator command signal in response thereto for regulating the piston movement; comparing a desired MAP signal to the measured pressure and generating an exhalation valve command signal in response thereto for regulating MAP at the patient; and centering said piston about said midpoint of full stroke of said piston while regulating MAP. - View Dependent Claims (2)
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3. A method of regulating movement of an oscillator piston of a patient ventilator using an oscillator controller comprising an oscillator pressure loop and a centering loop, the method comprising the steps of:
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in the oscillator pressure loop; measuring a pressure at the patient and generating a measured pressure signal representative thereof; filtering the measured pressure signal to limit bandwidth thereof to between a predetermined transition frequency and a noise-limiting frequency and generating a filtered pressure signal in response thereto; receiving a desired oscillator pressure signal; summing the filtered pressure signal and the desired oscillator pressure signal and generating an oscillator pressure error signal in response thereto; and filtering the oscillator pressure error signal through an oscillator pressure loop proportional integral (PIP) controller and generating a pressure output signal in response thereto; and in the centering loop; measuring a piston position with respect to a midpoint of full stroke of said piston and generating a piston displacement signal representative thereof; filtering the piston displacement signal to limit bandwidth thereof to between static and the predetermined transition frequency and generating a filtered displacement signal in response thereto; subtracting the filtered displacement signal from zero as a desired piston position and generating a displacement error signal in response thereto; filtering the displacement error signal through a centering loop proportional integral (PIX) controller and generating a displacement output signal in response thereto; summing the pressure and displacement output signals and generating the oscillator command signal in response thereto for driving the piston movement; and centering said piston about said midpoint of full stroke of said piston while regulating MAP. - View Dependent Claims (4, 5, 6, 7, 8)
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Specification