ADJUSTMENT OF TARGET VENTILATION IN A SERVOVENTILATOR
First Claim
1. A method for determining suitable ventilator settings in patients with alveolar hypoventilation during sleep, and for delivery of those settings comprising the steps of:
- measuring the ventilation of a patient during at least a latter portion of a learning period while the patient is awake;
determining a target ventilation from said measure of ventilation; and
slowly changing the target ventilation over a period of time, according to a programmed schedule implemented in a ventilator controller.
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Accused Products
Abstract
A servoventilator control slowly changes the target ventilation over a period of time, according to a preprogrammed schedule adapted to be set by the physician. Preferably, the target ventilation stays constant at an initial target ventilation for an initial hold time, and then increases at a constant rate until it reaches a final target ventilation, whereupon it stays constant thereafter. If the pressure support level is too high, possibly indicating glottic or upper airway closure, the rate of increase of target ventilation may be lowered or the final target ventilation not reached.
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Citations
11 Claims
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1. A method for determining suitable ventilator settings in patients with alveolar hypoventilation during sleep, and for delivery of those settings comprising the steps of:
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measuring the ventilation of a patient during at least a latter portion of a learning period while the patient is awake; determining a target ventilation from said measure of ventilation; and slowly changing the target ventilation over a period of time, according to a programmed schedule implemented in a ventilator controller. - View Dependent Claims (2, 3, 4)
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5. A method of non-invasive ventilation of a patient comprising the steps of:
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(i) ventilating a patient at a first level of ventilation for a first duration exceeding several breathing cycles; and (ii) at the expiration of the first duration, changing the level of ventilation from the first level to a second level over a second duration. - View Dependent Claims (6, 7, 8)
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9. A method for determining suitable ventilator settings in patients with alveolar hypoventilation during sleep, and for delivery of those settings comprising:
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(i) using a ventilator to learn the patient'"'"'s awake ventilation; (ii) setting an initial target ventilation to a proportion of said awake ventilation; (iii) setting a final target ventilation to the initial target ventilation multiplied by the ratio of a desired PCO2 value to a current PCO2 value; (iv) setting a target ventilation ramp time to a value, depending on the clinical urgency of lowering the PCO2 and the amount by which it is desired to lower the PCO2.
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10. A servoventilator apparatus comprising an electric motor having an impeller under the control of a controller circuit, that allows a flow of pressurized air to pass along an air delivery conduit to a patient interface;
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a pressure sense tube between the patient interface and a pressure sensor that allows the controller to sense pressure in the patient interface; a controller that determines the flow rate of air along the air delivery conduit via a flow sensor; means to allow setting appropriate target ventilations and ramp times, wherein the controller provides ventilation of a patient at a first level of ventilation for a first duration exceeding several breathing cycles; and at the expiration of the first duration, changes the level of ventilation from the first level to a second level over a second duration.
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11. A bilevel ventilation apparatus having a pressure support level and a controller programmed to increase the pressure support level at a selected rate after an initial hold time until it reaches a final pressure support level.
Specification