Flow path sensing for flow therapy apparatus
Systems and method for conducting respiratory therapy in a respiratory system can adjust a flow of respiratory gases to a patient based upon a detected patient breath cycle. The respiratory system can include a non-sealed patient interface. The respiratory system can be configured to deliver a high flow therapy. A patient breath cycle may be determined using one or more measured parameters, such as a flow rate, a blower motor speed, and/or a system pressure. A flow source may be adjusted to have a phase matching that of the patient's breath cycle, such that flow in increased in response to the patient inhaling, and decreased in response to the patient exhaling.
1. A respiratory therapy apparatus, comprising:
a blower for generating an air flow for a patient, the blower being associated with a blower motor, wherein the blower motor is configured to be driven by a control signal;
one or more sensors configured to measure at least a flow rate of the air flow; and
a control system configured to:
detect a breath cycle of the patient by:
receiving a first input comprising one or more flow rate measurements from the one or more sensors,
receiving a second input comprising one or more pressure measurements from at least one pressure sensor or one or more motor speed measurements associated with the blower motor, and
generating a breath cycle waveform using at least the received flow rate measurements, wherein the breath cycle waveform comprises a plurality of alternating periods of the patient's inspiration and expiration, and
synchronize the control signal with the breath cycle waveform by:
identifying a phase of the breath cycle waveform, and
iteratively updating a phase of the control signal to achieve a determined phase difference between the control signal and the breath cycle waveform, such that the control signal is configured to adjust a speed of the blower motor based upon the patient's inspiration and expiration;
wherein a magnitude of the control signal is determined based at least in part upon an amplitude of the breath cycle waveform.
2. The respiratory therapy apparatus of claim 1 , wherein the control system is further configured to phase-shift the control signal based upon a system delay between the control signal being received by the blower motor and the resulting air flow being sensed.
3. The respiratory therapy apparatus of claim 1 , wherein the control system is further configured to phase-shift the control signal, such that the control signal pre-empts the breath cycle waveform by a set amount of time.
4. The respiratory therapy apparatus of claim 1 , wherein the one or more sensors comprises an ultrasonic sensor assembly.
5. The respiratory therapy apparatus of claim 1 , wherein the one or more sensors further comprises a heated temperature sensing element.
6. The respiratory therapy apparatus of claim 1 , wherein the control signal is phase-locked to the breath cycle waveform.
7. The respiratory therapy apparatus of claim 1 , wherein the breath cycle waveform is used to calculate a patient breath rate.
8. The respiratory therapy apparatus of claim 1 , wherein the magnitude of the control signal is further determined based at least in part upon a positive feedback parameter and a negative feedback parameter.
9. The respiratory therapy apparatus of claim 1 , wherein the second input is the one or more motor speed measurements associated with the blower motor.
10. The respiratory therapy apparatus of claim 9 , wherein the breath cycle waveform is generated using the received flow rate measurement and the one or more motor speed measurements.
11. The respiratory therapy apparatus of claim 9 , wherein the breath cycle waveform is generated based at least in part upon a calculated patient flow, wherein the patient flow is based upon a system leak calculated using the received flow rate measurement and the one or more motor speed measurements.
12. The respiratory therapy apparatus of claim 9 , wherein the one or more motor speed measurements are determined based at least in part upon one or more blower motor parameters.
13. The respiratory therapy apparatus of claim 1 , wherein the blower motor comprises a brushless DC motor.
14. The respiratory therapy apparatus of claim 9 , wherein the control system is configured to detect the breath cycle by receiving a third input comprising the one or more pressure measurements from the at least one pressure sensor.
15. The respiratory therapy apparatus of claim 1 , wherein the second input is the one or more pressure measurements from the at least one pressure sensor.
16. The respiratory therapy apparatus of claim 1 , wherein the respiratory therapy apparatus is a respiratory high flow therapy apparatus.
17. The respiratory therapy apparatus of claim 1 , wherein the respiratory therapy apparatus is configured for use in a non-sealed respiratory system.
18. The respiratory therapy apparatus of claim 1 , wherein the respiratory therapy apparatus is configured for use in a sealed respiratory system.
19. The respiratory therapy apparatus of claim 18 , wherein the respiratory therapy apparatus is configured to adjust the speed of the blower motor to achieve a predetermined pressure of the sealed respiratory system based on the one or more pressure measurements from the at least one pressure sensor.
20. The respiratory therapy apparatus of claim 19 , wherein the respiratory therapy apparatus is configured to be coupled with a non-invasive ventilation mask.
21. The respiratory therapy apparatus of claim 20 , wherein the at least one pressure sensor is located in the non-invasive ventilation mask, or a manifold connecting the non-invasive ventilation mask to a patient breathing conduit, or within the patient breathing conduit, or within a housing of the respiratory therapy apparatus.