Adaptive cycling for respiratory treatment apparatus
A controller or processor(s) implements detection of respiratory related conditions that may serve as control logic to synchronize pressure treatment delivery with a patient's respiratory cycle. Based on data derived from sensor signals associated with the respiratory treatment, a monitoring device, detector or respiratory treatment apparatus may evaluate flow measures from a flow sensor and distinguish flow attributable to the respiratory treatment apparatus and flow attributable to patient respiratory muscles. The determination may serve as a basis of synchronization criteria that controls pressure levels from a pressure treatment apparatus, such as by evaluating the determined patient generated flow or a relationship between total flow and apparatus flow. In some embodiments, data for the cycling conditions is determined in preliminary treatment cycles during which synchronized pressure changes are controlled according to other cycling criteria. The new cycling conditions are then automatically initiated for control of synchronization in subsequent cycles.
1. An automated processing method to determine a signal indicative of patient respiration for synchronization of a respiratory treatment apparatus, the method comprising:
determining, by a processor, a first inspiratory flow measure with a flow sensor, the first inspiratory flow measure representing a total measured inspiratory flow;
determining, by the processor, a second inspiratory flow measure; and
determining, by the processor, a patient respiration measure as a function of the first inspiratory flow measure, the second inspiratory flow measure and an estimate of respiratory resistance and compliance derived from an expiratory portion of a flow measure of the flow sensor, the patient respiratory measure representing patient respiratory muscle effort, the patient respiration measure comprising a difference of the first inspiratory flow measure and the second inspiratory flow measure; and
determining, by the processor, a timing for switching a pressure treatment based on the respiration measure.
2. The method of claim 1 wherein the second inspiratory flow measure is a measure of flow attributable to the respiratory treatment apparatus.
3. The method of claim 2 further comprising calculating a resistance value for the estimate.
4. The method of claim 3 wherein the calculating of the resistance value comprises a function of airway pressure and flow.
5. The method of claim 4 further comprising calculating a compliance value for the estimate.
6. The method of claim 5 wherein the calculating the resistance and compliance values comprises multiple linear regression processing of an expiratory breath data portion, the expiratory breath data portion beginning with expiration and ending before a next inspiration.
7. The method of claim 6 wherein the ending before the next inspiration comprises a percentage of expired tidal volume.
8. The method of claim 2 further comprising calculating the difference of the first inspiratory flow measure and the second inspiratory flow measure by subtraction.
9. A monitoring apparatus to determine a signal indicative of patient respiration for synchronization of a respiratory treatment apparatus, the monitoring apparatus comprising:
a controller having at least one processor to access data representing a measured flow of breathable gas from a flow sensor, the controller being further configured to:
determine a first inspiratory flow measure with the data, the first inspiratory flow measure representing a total measured inspiratory flow;
determine a second inspiratory flow measure;
determine a patient respiration signal as a function of the first inspiratory flow measure, the second inspiratory flow measure and an estimate of respiratory resistance and compliance derived from an expiratory portion of a flow measure of the flow sensor, the patient respiratory signal representing patient respiratory muscle effort, the patient respiration measure comprising a difference of the first inspiratory flow measure and the second inspiratory flow measure; and
determine a timing for switching a pressure treatment based on the respiration signal.
10. The monitoring apparatus of claim 9 wherein the controller is further configured to calculate a resistance value for the estimate.
11. The monitoring apparatus of claim 10 wherein the calculation of the resistance value comprises a function of airway pressure and flow.
12. The monitoring apparatus of claim 11 wherein the controller is further configured to calculate a compliance value for the estimate.
13. The monitoring apparatus of claim 12 wherein the calculation of the resistance and compliance values of the estimate is performed by the controller in multiple linear regression processing of an expiratory breath data portion, the expiratory breath data portion beginning with expiration and ending before a next inspiration.
14. The monitoring apparatus of claim 13 wherein the ending before the next inspiration comprises a percentage of expired tidal volume.
15. The monitoring apparatus of claim 9 wherein the controller is further configured to calculate the difference of the first inspiratory flow measure and the second inspiratory flow measure by subtraction.