System and method for circuit compliance compensated volume control in a patient respiratory ventilator
First Claim
1. A circuit compliance compensated volume control system in a patient respiratory ventilation system, comprising:
- a circuit compliance estimator, to provide a relationship between a circuit volume VCC and a differential pressure Δ
PY between a circuit pressure PY and a PEEP of the respiratory circuit;
a circuit volume estimator, operative to provide an estimated circuit volume VOLCKT—
EST based on the relationship between VCC and Δ
PY;
a patient volume observer, operative to provide an estimated patient volume VOLTID—
EST by subtracting the estimated circuit volume VOLCKT—
EST from a machine delivered net volume as measured and denoted as VOLNET; and
a volume delivery controller, operative to update the machine delivered net volume VOLSYS based on the estimated patient volume VOLTID—
EST and a set tidal volume VOLTID—
SET.
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Accused Products
Abstract
A system and a method for circuit compliance compensated volume control in a patient respiratory ventilation system having a flow regulated feedback servo control loop, a volume delivery controller, and a patient volume observer. In the flow regulated feedback servo control loop, an estimate of patient volume is used for feedback control, such that a tidal volume is achieved upon servo regulation, and the peak inspiratory flow is modulated based on volume error between the set tidal volume and the estimated patient volume. Thereby, a constant inspiratory time and a constant I:E ratio can be maintained. In the volume delivery control, the feedback volume error is normalized to a volume error percentage, and the gain of the controller is dynamically changed based on the volume error percentage, such that the controller effort can be minimized when the volume target is approached. The patient volume observer is operative to estimate the patient delivered volume based on the estimated circuit volume and the measured net delivered volume, while the measured net delivered volume includes effects of leaks and valve dynamics and is synchronously captured with true patient breathing.
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Citations
61 Claims
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1. A circuit compliance compensated volume control system in a patient respiratory ventilation system, comprising:
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a circuit compliance estimator, to provide a relationship between a circuit volume VCC and a differential pressure Δ
PY between a circuit pressure PY and a PEEP of the respiratory circuit;
a circuit volume estimator, operative to provide an estimated circuit volume VOLCKT — EST based on the relationship between VCC and Δ
PY;
a patient volume observer, operative to provide an estimated patient volume VOLTID — EST by subtracting the estimated circuit volume VOLCKT— from a machine delivered net volume as measured and denoted as VOLNET; and
EST
a volume delivery controller, operative to update the machine delivered net volume VOLSYS based on the estimated patient volume VOLTID — EST and a set tidal volume VOLTID— SET. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A circuit compliance compensated volume control system in a patient respiratory ventilation system, comprising:
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a virtual sensor operative to provide a measured patient volume VOLTID — Y or to estimate a patient volume VOLTID— EST based on a measured machine delivered net volume VOLNET and a circuit compliance of a patient circuit of the ventilation system; and
a volume delivery controller, operative to provide a circuit compliance volume compensation factor VOLTID — CTL based on the measure patient volume VOLTID— Y or the estimated patient volume VOLTID— EST and a set tidal volume VOLTID— SET. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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37. A ventilation system, comprising:
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a ventilator having an inspiratory port for supplying an inspiratory gas to a patient and an expiratory port for receiving an expiratory gas from the patient;
a patient circuit having an inspiratory limb having one end connected to the inspiratory port, an expiratory limb having one end connected to the expiratory port, and a patient piece having one end merging the other ends of the inspiratory and expiratory limbs and the other end connected to the patient; and
a circuit compliance compensated volume control system, comprising;
a patient volume observer operative to estimate a patient volume VOLTID — EST based on a measured machine delivered net volume VOLNET and a circuit compliance of the patient circuit, or to provide a patient volume VOLTID— Y measured at the patient piece of the patient circuit; and
a volume delivery controller, operative to output a circuit compliance volume compensation factor VOLTID — CTL based on the estimated or measured patient volume VOLTID— EST or VOLTID— Y and a set tidal volume VOLTID— SET, so as to update an inspiratory flow QINSP— SET. - View Dependent Claims (38, 39, 40, 41, 42, 43)
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44. A method for circuit compliance compensated volume control in a patient respiratory ventilation system, comprising:
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a) estimating a patient volume VOLTID — EST based on a machine delivered net volume and a circuit compliance of a patient circuit of the patient respiratory ventilation system, or measuring a patient volume VOLTID— Y via a flow sensor located at a patient piece of the patient circuit; and
b) updating a circuit compliance volume compensation factor VOLTID — CTL based on a set tidal volume VOLTID— SET and a feedback volume error VOLTID— ERR, wherein the circuit compliance volume compensation factor VOLTID— CTL has an initial setup value INI_CKT_VOL and the feedback volume VOLTID— ERR is defined as a volume differential between the patient volume VOLTID— EST or VOLTID— Y and the set tidal volume VOLTID— SET. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. A circuit compliance compensated volume control method used for a patient receiving a machine ventilation through a patient circuit, comprising:
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providing a measured patient volume or an estimated patient volume by subtracting a circuit volume estimated based on a circuit compliance of the patient circuit from a measured machine delivered net volume;
estimating a feedback volume error by computing a volume differential between the patient volume and a set tidal volume;
weighing the feedback volume error by a gain defined by a ratio between an absolute value of the feedback volume error and the set tidal volume;
presetting an initial value of a circuit compliance volume compensation factor; and
updating the circuit compliance volume compensation factor based on the feedback volume error weighed by the gain. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61)
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Specification