Method and apparatus to counterbalance intrinsic positive end expiratory pressure
AssigneeResMed Limited
InventorsMichael Berthon-Jones, Michael Hallett
Life of this patent
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Abstract
The invention prevents dynamic airway compression during ventilatory support of a patient. The respiratory airflow is determined by measurement or calculation, and a measure of the degree of dynamic airway compression is derived from the determined airflow. This measure is servo-controlled to be zero by increasing expiratory pressure if the measure of the degree of dynamic airway compression is large or increasing, and by reducing expiratory pressure if the measure of the degree of dynamic airway compression is small or zero.
Claims31
1-22. (canceled)
A method for preventing dynamic airway compression during ventilatory support of a patient comprising the steps of:
- providing an interface to the patient's airway,
- providing said interface with a supply of breathable gas at a controllable pressure and with an exhaust,
- determining the patient's respiratory airflow,
- varying the pressure at the patient interface so as to provide ventilatory support to the patient,
- from at least the respiratory airflow determining the patient's airway conductance separately during the inspiratory and expiratory portions of at least one respiratory cycle and calculating a measure of the degree of dynamic airway compression as a function of the values of the inspiratory conductance and the expiratory conductance, and
- servo-controlling the measure of the degree of dynamic airway compression by increasing expiratory pressure if said measure is large or increasing, and reducing expiratory pressure if said measure is small or zero.
A method for preventing dynamic airway compression during ventilatory support of a patient comprising the steps of:
- providing a variable pressure to the patient's airway so as to provide ventilatory support,
- determining the patient's respiratory airflow,
- measuring the patient's airway conductance separately during the inspiratory and expiratory portions of at least one respiratory cycle and calculating as a function of the determined respiratory airflow and the values of the inspiratory and expiratory conductances a measure of the degree of the patient's dynamic airway compression, and
- increasing or decreasing expiratory pressure in accordance with the calculated measure of the degree of dynamic airway compression.
An apparatus for determining a pressure response to ameliorate dynamic airway compression during ventilatory support comprising:
- an interface to a patient's airway and an exhaust,
- a means for supplying breathable gas at a controllable pressure to the interface,
- a means for deriving an airflow signal from said interface, and
- a controller means adapted for:
- (a) controlling a variation of the pressure at the interface to provide ventilatory support to the patient;
- (b) controlling a determination of a measure of the degree of dynamic airway compression at least from data representing the airflow signal;
- and
- (c) servo-controlling the measure of the degree of dynamic airway compression by increasing the controllable pressure during expiration if the measure of the degree of dynamic airway compression is large or increasing, and decreasing the controllable pressure during expiration if the measure of the degree of dynamic airway compression is small or zero.
An apparatus for determining a pressure response to ameliorate dynamic airway compression during ventilatory support comprising:
- an interface to a patient's airway and an exhaust,
- a means for supplying breathable gas at a controllable pressure to the interface,
- a transducer for determining an airflow signal from said interface, and
- a processor with programmed instructions for controlling:
- (a) a variation of the pressure at the interface to provide ventilatory support to the patient;
- (b) a determination of a measure of a degree of dynamic airway compression as a function of data representing the airflow signal;
- and
- (c) increasing or decreasing expiratory pressure in accordance with the derived measure of the degree of dynamic airway compression.
A storage medium with programmed instructions for use by an electronic processor to control a determination of a pressure response to ameliorate dynamic airway compression during ventilatory support, the instructions controlling the execution of the steps of:
- (a) varying a pressure value so as to control a provision of ventilatory support;
- (b) determining a measure of a degree of dynamic airway compression at least from calculated data representing measured airflow;
- and
- (c) servo-controlling the measure of the degree of dynamic airway compression by increasing the controllable pressure during expiration if the measure of the degree of dynamic airway compression indicates a need therefor, and decreasing the controllable pressure during expiration if the measure of the degree of dynamic airway compression is small or zero.
A method for preventing dynamic airway compression during ventilatory support of a patient comprising the steps of:
- providing a variable pressure device to supply pressure to the patient's airway so as to provide ventilatory support,
- providing an automatic apparatus for determining respiratory airflow and quantifying therefrom a degree of dynamic airway compression;
- determining the patient's respiratory airflow, and
- increasing or decreasing expiratory pressure automatically in accordance with the quantified degree of dynamic airway compression.
Dependencies are inferred from the claim text.