US-12616814-B2 - Patient specific auto-flowrate control

Abstract

A respiratory assistance system can provide high flow therapy to patients. The respiratory assistance system can include a patient interface that can deliver a gas flow to a patient and a gas source that can drive the gas flow towards the patient interface at an operating flow rate. The system can include a controller for controlling the operating flow rate of the gas. The controller can apply multiple test flow rate values in a range as the operating flow rate. For each of the test flow rate values, the controller can measure a patient parameter. The controller can determine a new flow rate value based on the measured patient parameters. Patient parameters can include respiration rate, work of breathing, or any other parameters related to the respiratory circuit.

Inventors

• Matthew Jon Payton
• Callum James Thomas Spence
• Alicia Jerram Hunter Evans
• Andreas Schibler
• Craig Karl White
• Samantha Dale Oldfield

Assignees

• FISHER & PAYKEL HEALTHCARE LIMITED

Dates

Publication Date

20260505

Application Date

20230831

Claims (18)

1. 1 . A method for providing respiratory support using a respiratory assistance system during a medical procedure including administration of anesthesia, said method comprising: during the medical procedure including administration of anesthesia to a patient: providing a gas flow at an operating flow rate to the patient via a patient interface, wherein the patient interface comprises an unsealed patient interface, and wherein the operating flow rate is at least 20 L/min; applying a plurality of test flow rate values in a range as the operating flow rate, wherein the plurality of test flow rate values are at least 20 L/min; measuring at least one patient parameter corresponding to each of the plurality of test flow rate values; determining a new flow rate value based at least in part on the at least one patient parameter, wherein the new flow rate is at least 20 L/min; and providing an output relating to changing the operating flow rate based on the new flow rate, wherein the at least one patient parameter comprises a CO2 indicator measured by capnography.
2. 2 . The method of claim 1 , further comprising determining a rate of change in the at least one patient parameter as a function of a change in the applied test flow rate values.
3. 3 . The method of claim 2 , further comprising determining a value in the range of the plurality of test flow rate values at which the rate of change in the measured at least one patient parameter approaches zero.
4. 4 . The method of claim 1 , wherein said determining the new flow rate value further comprises determining a minimum value or a maximum value of the measured at least one patient parameter for each of the plurality of test flow rate values.
5. 5 . The method of claim 1 , wherein the at least one patient parameter further comprises a respiratory rate and wherein the method further comprises measuring the respiratory rate based at least in part on one or more of the following measurements: pressure fluctuations, flow rate fluctuations, a blower fans speed, a blower motor power, a blower motor torque, expired CO2 fluctuations, transcutaneous CO2 fluctuations, an expired patient temperature, EMG signals, Edi signals, impedance pneumography, respiratory inductance plethysmography, or acoustic sensing.
6. 6 . The method of claim 1 , wherein the CO2 indicator is an expiratory CO2 concentration indicator.
7. 7 . The method of claim 1 , further comprising waiting a predetermined time period after the change in the operating flow rate before measuring the at least one patient parameter.
8. 8 . The method of claim 1 , wherein the range comprises one of the following: 0.5-1.5; 1-2; 1.5-2.5; 2-3; 0.5-4; 1-3; 2-3; or 1-4 (in L/min/kg).
9. 9 . The method of claim 1 , wherein said changing the operating flow rate comprises changing an amount of power delivered to a gas source configured to drive the gas flow.
10. 10 . The method of claim 1 , further comprising generating an alarm based on the measured at least one patient parameter.
11. 11 . The method of claim 10 , wherein said generating an alarm is in response to determining that the measured at least one patient parameter is insensitive to the change in the operating flow rate.
12. 12 . The method of claim 1 , wherein said plurality of test flow rate values are applied responsive to a user input.
13. 13 . The method of claim 1 , wherein the respiratory assistance system comprises a humidifier, the humidifier disposed between the patient interface and a gas source, the humidifier configured to humidify the gas from the gas source prior to delivery to the patient through the patient interface.
14. 14 . The method of claim 1 , further comprising changing the operating flow rate to the new flow rate.
15. 15 . The method of claim 1 , wherein the range comprises one of the following: 20-120; 20-60; or 60-120 (in L/min).
16. 16 . The method of claim 2 , wherein the range is 50-70 (in L/min).
17. 17 . The method of claim 1 , wherein the output maximizes an end tidal oxygen volume of the patient.
18. 18 . The method of claim 1 , wherein the medical procedure includes a preoxygenation of the patient prior to administration of anesthesia to the patient.

Description

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 16/909,748, filed Jun. 23, 2020, which is a continuation of U.S. patent application Ser. No. 15/521,874, filed Apr. 25, 2017, which is a U.S. National Phase of International Patent Application No. PCT/NZ2015/050179, filed Oct. 28, 2015, now U.S. Pat. No. 10,722,670, which claims the priority benefit of U.S. Provisional Application No. 62/069,760, filed Oct. 28, 2014, the entirety of which is hereby incorporated by reference herein. Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. BACKGROUND A respiratory assistance system including a humidification apparatus may be used to deliver heated and humidified respiratory gases to a patient through a conduit and a patient interface. The respiratory assistance system can provide a number of therapies for patients requiring respiratory support. One of the therapies includes providing a high flow therapy. In high flow therapy, the respiratory support system delivers relatively high flows of gases through an interface, such as an unsealed nasal cannula. The flow rate of gases can be in the range of 5 L/min to 120 L/min for patients. SUMMARY Certain aspects, advantages and novel features of the present disclosure are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the present disclosure. Thus, the features, aspects, and advantages of the present disclosure may be embodied or carried out in a manner that achieves or selects one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. In certain embodiments, a respiratory assistance system can include a patient interface that can deliver a gas flow to a patient. The respiratory assistance system can also include a gas source that can drive the gas flow to the patient interface at an operating flow rate. The respiratory assistance system can also include a hardware processor. The hardware processor can apply a plurality of test flow rate values in a range as the operating flow rate. The hardware processor can further measure at least one patient parameter corresponding to each of the plurality of test flow rate values. The hardware processor can also determine a new flow rate value based at least in part on the measured at least one patient parameter. In some embodiments, the hardware processor changes the operating flow rate to the new flow rate value. The system of the preceding paragraph can have any sub-combination of the following features: wherein the hardware processor can further determine a rate of change in the measured at least one patient parameter as a function of the change in the applied plurality of test flow rate values; wherein said determining the new flow rate further includes determining where in the range of the plurality of test flow rate values does the rate of change approach zero; wherein said determining the new flow rate can further include determining a minimum or a maximum value of the at least one patient parameter measured for each of the plurality of test flow rate values; wherein the at least one patient parameter comprises a respiratory rate and wherein the hardware processor can measure the respiratory rate based at least in part on one or more of the following sensor measurements: pressure fluctuations, flow rate fluctuations, blower fans speed, blower motor power, blower motor torque, expired CO2 fluctuations, transcutaneous CO2 fluctuations, expired patient temperature, EMG signals, Edi signals, impedance pneumography, respiratory inductance plethysmography, acoustic sensing; wherein the at least one patient parameter can include a work of breathing indicator; wherein the patient parameter can include an expiratory CO2 concentration indicator; wherein the patient parameter can include a thoracoabdominal asynchrony indicator; wherein the hardware processor can wait a predetermined time period after the change in the operating flow rate before measuring the patient parameter; wherein the range can include one of the following: 0.5-1.5; 1-2; 1.5-2.5; 2-3; 0.5-4; 1-3; 2-3; and 1-4 (in L/min/kg); wherein the range can include one of the following: 5-120; 5-60; 20-120; 20-60; 60-120; and 50-70 (in L/min) for patients; wherein changing the operating flow rate can include changing an amount of power delivered to the gas source; wherein the gas source can include a blower; wherein the hardware processor can generate an alarm value based at least in part on the measured at least one patient parameter; wherein the hardware processor is can determine that the measured at least one patient parameter is insensitive to the change in flow rate a