Closed loop oxygen control
The present disclosure provides for a flow therapy apparatus that can implement one or more closed loop control systems to control the flow of gases of a flow therapy apparatus. The flow therapy apparatus can monitor blood oxygen saturation (SpO2) of a patient and control the fraction of oxygen delivered to the patient (FdO2). The flow therapy apparatus can automatically adjust the FdO2 in order to achieve a targeted SpO2 value for the patient.
1. A respiratory apparatus that provides a flow of gases to a patient, wherein the respiratory apparatus is configured to deliver high flow therapy to the patient, the respiratory apparatus comprising:
a gases composition sensor configured to determine at least a measured fraction of delivered oxygen content (FdO2) of gases flow during operation of the respiratory apparatus, wherein the gases composition sensor is an ultrasonic sensor system;
a controller configured to control delivery of gases to the patient using closed loop control, wherein the controller is configured to:
receive patient parameter data indicative of oxygen saturation (SpO2) of the patient from at least one sensor;
execute a control phase, wherein operation of the respiratory apparatus during a therapy session is based at least in part on the patient parameter data, wherein the control phase includes determining a target FdO2, wherein the target FdO2 is determined based at least in part on a target SpO2, measured SpO2, measured FdO2, and a previous target FdO2.
2. The respiratory apparatus of claim 1 wherein the respiratory apparatus is configured to deliver a nasal high flow (NHF) flow of gases to the patient.
3. The respiratory apparatus of claim 1 , wherein the controller is configured to receive device parameter data indicative of an oxygen concentration of the gases flow.
4. The respiratory apparatus of claim 1 further comprising a supplementary gas inlet valve, wherein the controller is configured to control operation of the supplementary gas inlet valve.
5. The respiratory apparatus of claim 4 further comprising an ambient air inlet, wherein the supplementary gas inlet valve is an oxygen inlet valve, wherein the oxygen inlet valve is in fluid communication with a filter module, wherein the respiratory apparatus is configured to entrain oxygen received from the oxygen inlet valve with ambient air from the ambient air inlet in the filter module.
6. The respiratory apparatus of claim 5 , wherein the gases composition sensor is positioned downstream of a blower module of the respiratory apparatus, and wherein the filter module is positioned upstream of the blower module of the respiratory apparatus.
7. The respiratory apparatus of claim 1 , wherein the gases composition sensor is positioned downstream of a blower module of the respiratory apparatus.
8. The respiratory apparatus of claim 1 , wherein the closed loop control includes using a second closed loop control model configured to determine a control signal for an oxygen inlet valve based at least in part on a difference between the target FdO2 and a measured FdO2.
9. The respiratory apparatus of claim 8 , wherein the control signal for the oxygen inlet valve is determined further based at least in part on a gases flow rate, wherein the gases flow rate is a total gases flow rate.
10. The respiratory apparatus of claim 1 , wherein the controller is configured to transfer to a manual mode of operation when a signal quality of the at least one sensor is below a threshold.
11. The respiratory apparatus of claim 1 , wherein the controller is configured to transfer to a manual mode of operation when the patient SpO2 is outside of defined limits.
12. The respiratory apparatus of claim 11 , wherein the controller is configured to trigger an alarm when the patient SpO2 is outside of the defined limits.
13. The respiratory apparatus of claim 1 wherein the ultrasonic sensor system comprises a first ultrasonic transducer and a second ultrasonic transducer.
14. The respiratory apparatus of claim 13 wherein each of the first ultrasonic transducer and the second ultrasonic transducer is a receiver and a transmitter.
15. The respiratory apparatus of claim 14 wherein the first ultrasonic transducer and the second ultrasonic transducer send pulses bidirectionally.
16. The respiratory apparatus of claim 13 wherein at least one of the first ultrasonic transducer or the second ultrasonic transducer send pulses along the gases flow.
17. The respiratory apparatus of claim 13 wherein at least one of the first ultrasonic transducer or the second ultrasonic transducer send pulses across the gases flow.