Methods and apparatus for the systemic control of ventilatory support in the presence of respiratory insufficiency
First Claim
1. A method for adjusting the-ventilatory pressure support provided to a patient comprising:
- determining, with a processor, a flow rate of air delivered to the patient and calculating therefrom a measure of a function of respiratory airflow of the patient,determining, with the processor, an adjustment to the ventilatory pressure support in a direction that tends to reduce a difference between the measure of the function of respiratory airflow and a target value, anddetermining, with the processor, a rate at which the determined adjustment of ventilatory pressure support is made based on a magnitude of the difference between the measure of the function of respiratory airflow and the target value such that the rate is a product of a gain and a ventilation error, the ventilation error comprising the magnitude of the difference, and wherein said gain is also varied as a function of the ventilation error; and
controlling, with the processor, the adjustment of ventilatory pressure support, wherein an increase of the magnitude of the difference between the measure of the function of respiratory airflow and the target value corresponds to an increase in the rate at which the determined adjustment is made.
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Accused Products
Abstract
A method and apparatus for providing ventilatory assistance to a spontaneously breathing patient. An error signal is computed that is the difference between a function of respiratory airflow over a period of time and a target value. Using a servo loop, air is delivered to the patient at a pressure that is a function of the error signal, the phase of the current breathing cycle, and a loop gain that varies depending on the magnitude of the error signal. The loop gain increases with the magnitude of the error signal, and the gain is greater for error signals below a ventilation target than for error signals above the ventilation target value. The target value is an alveolar ventilation that takes into account the patient'"'"'s physiologic dead space.
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Citations
37 Claims
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1. A method for adjusting the-ventilatory pressure support provided to a patient comprising:
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determining, with a processor, a flow rate of air delivered to the patient and calculating therefrom a measure of a function of respiratory airflow of the patient, determining, with the processor, an adjustment to the ventilatory pressure support in a direction that tends to reduce a difference between the measure of the function of respiratory airflow and a target value, and determining, with the processor, a rate at which the determined adjustment of ventilatory pressure support is made based on a magnitude of the difference between the measure of the function of respiratory airflow and the target value such that the rate is a product of a gain and a ventilation error, the ventilation error comprising the magnitude of the difference, and wherein said gain is also varied as a function of the ventilation error; and controlling, with the processor, the adjustment of ventilatory pressure support, wherein an increase of the magnitude of the difference between the measure of the function of respiratory airflow and the target value corresponds to an increase in the rate at which the determined adjustment is made. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. Apparatus for providing ventilatory assistance to a spontaneously breathing patient comprising:
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a processor for determining a flow rate of air delivered to the patient, computing a measure of a difference between a function of respiratory airflow and a target value, determining an adjustment to ventilation support in a direction that tends to reduce a difference between the measure of the function of respiratory airflow and a target value, and determining a rate at which the determined adjustment of ventilation support is made based on a magnitude of the difference between the measure of the function of respiratory airflow and the target value, and a controller for controlling a blower to deliver breathable gas to the patient at a pressure that is a function of said difference measure, the controller using a blower in a servo-controlled loop with a gain that varies depending on a magnitude of said difference measure such that the rate is a product of the gain and a ventilation error, the ventilation error comprising the magnitude of the difference, and wherein said gain is also varied as a function of the ventilation error. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification