Automatic control of temperature in a patient circuit

• US 10,143,821 B2
• Filed: 04/27/2011
• Issued: 12/04/2018
• Est. Priority Date: 06/04/2010
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Pujol, Jr., John Raymond
• Primary Examiner(s): Anderson, Gregory
• Assistant Examiner(s): Ruddie, Elliot S
• Application Number:
  US13/701,563
• Publication Number:
  US 20130073013A1
• Time in Patent Office: 2,778 Days
• Field of Search: 12823027
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/1075 by influencing the temperature A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/1095 in the connecting tubes
• CPC Class Codes: A61M 16/161 with means for measuring the humidity
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/3372 Temperature compensation

Abstract

A method of automatically controlling the temperature of a patient circuit (56, 58) of a pressure support system (50) includes determining (directly measuring or estimating/deriving) one or more environmental parameters relating to environmental conditions around the pressure support system, such as ambient temperature and/or ambient humidity, determining a desired temperature based on at least the one or more environmental parameters, and controlling the operation of a heating apparatus (70) operatively associated with the patient circuit based on the desired temperature. Also, a pressure support system implementing the method.

Claims

1. A respiratory therapy system having a temperature controlled patient circuit, the system comprising:

a pressure support system including;

a pressure generator configured to generate a pressurized flow of breathable gas for delivery to an airway of a subject;

the patient circuit configured to communicate the pressurized flow of breathable gas to the airway of the subject; and

one or more sensors configured to generate output signals conveying information related to an ambient temperature around the pressure support system, an ambient humidity around the pressure support system, a temperature of the pressurized flow of breathable gas, and a humidity of the pressurized flow of breathable gas; and

one or more processors configured by machine-readable instructions to;

determine the ambient temperature and the ambient humidity around the pressure support system based on the output signals;

determine the temperature and the humidity of the pressurized flow of breathable gas based on the output signals;

determine a desired temperature for the patient circuit based on (i) the determined ambient temperature and ambient humidity, (ii) the determined temperature and humidity of the pressurized flow of breathable gas, and (iii) one or more physical characteristics of the patient circuit, the physical characteristics of the patient circuit including one or more of a thermal conductivity of the patient circuit, a length of the patient circuit, or a surface area of the patient circuit; and

control an operation of a heating apparatus operatively associated with the patient circuit based on the determined desired temperature.

2. The system of claim 1, wherein the heating apparatus comprises a heating coil disposed adjacent to or with the patient circuit and wherein the one or more processors are configured such that controlling the operation of the apparatus comprises controlling one or more of a duty cycle, or one or more pulse width modulation parameters associated with the heating coil.

3. The system of claim 1, wherein desired temperature is a minimum temperature required to prevent condensation within the patient circuit.

4. The system of claim 1, wherein the pressure support system further comprises a flow sensor disposed in line with the patient circuit, the flow sensor configured to generate output signals conveying information related to a flow of the pressurized flow of breathable gas and wherein the one or more processors are further configured to:

determine, based on the flow sensor output signals, a flow rate of the pressurized flow of breathable gas; and

determine the desired temperature for the patient circuit based on the determined flow rate.

5. The system of claim 1, wherein the one or more sensors comprise one or more of a temperature sensor, a humidity sensor, an ambient temperature sensor, or an ambient humidity sensor removably coupled with the pressure support system.

16. The system of claim 1, wherein the physical characteristics of the patient circuit include one or more of the length of the patient circuit, or the surface area of the patient circuit.

6. A method for automatically controlling a temperature of a patient circuit with a patient circuit heating system, the patient circuit heating system comprising a pressure support system, one or more sensors, and one or more processors, the method comprising:

generating, with the one or more sensors, output signals conveying information related to an ambient temperature around the pressure support system, an ambient humidity around the pressure support system, a temperature of a pressurized flow of breathable gas generated by the pressure support system, and a humidity of the pressurized flow of breathable gas;

determining, with the one or more processors, the ambient temperature and the ambient humidity around the pressure support system based on the output signals;

determining, with the one or more processors, the temperature and the humidity of the pressurized flow of breathable gas based on the output signals;

determining, with the one or more processors, a desired temperature for the patient circuit based on (i) the determined ambient temperature and ambient humidity, (ii) the determined temperature and humidity of the pressurized flow of breathable gas, and (iii) one or more physical characteristics of the patient circuit, the physical characteristics of the patient circuit including one or more of a thermal conductivity of the patient circuit, a length of the patient circuit, or a surface area of the patient circuit; and

controlling, with the one or more processors, an operation of a heating apparatus operatively associated with the patient circuit based on the determined desired temperature.

7. The method of claim 6, wherein the heating apparatus comprises a heating coil disposed adjacent to or with the patient circuit and wherein controlling the operation of the heating apparatus comprises controlling one or more of a duty cycle, or one or more pulse width modulation parameters associated with the heating coil.

8. The method of claim 6, wherein desired temperature is a minimum temperature required to prevent condensation within the patient circuit.

9. The method of claim 6, wherein the pressure support system further comprises a flow sensor disposed in line with the patient circuit, the flow sensor configured to generate output signals conveying information related to a flow of the pressurized flow of breathable gas, the method further comprising:

determining, with the one or more processors, a flow rate of the pressurized flow of breathable gas based on the flow sensor output signals; and

determining, with the one or more processors, the desired temperature for the patient circuit based on the determined flow rate.

10. The method of claim 6, wherein the one or more sensors comprise one or more of a temperature sensor, a humidity sensor, an ambient temperature sensor, or an ambient humidity sensor removably coupled with the pressure support system.

17. The method of claim 6, wherein the physical characteristics of the patient circuit include one or more of the length of the patient circuit, or the surface area of the patient circuit.

11. A respiratory therapy system having a temperature controlled patient circuit, the system comprising:

a pressure support system including;

means for generating a pressurized flow of breathable gas for delivery to an airway of a subject; and

means for communicating the pressurized flow of breathable gas to the airway of the subject;

means for determining an ambient temperature and an ambient humidity around the pressure support system;

means for determining a temperature and a humidity of the pressurized flow of breathable gas;

means for determining a desired temperature for the means for communicating based on (i) the determined ambient temperature and ambient humidity, (ii) the determined temperature and humidity of the pressurized flow of breathable gas, and (iii) one or more physical characteristics of the means for communicating, the physical characteristics of the means for communicating including one or more of a thermal conductivity of the means for communicating, a length of the means for communicating, or a surface area of the means for communicating; and

means for controlling an operation of a heating apparatus operatively associated with the means for communicating based on the determined desired temperature.

12. The system of claim 11, wherein the heating apparatus comprises a heating coil disposed adjacent to or with the means for communicating and wherein the means for controlling the operation of a heating apparatus comprises means for controlling one or more of a duty cycle, or one or more pulse width modulation parameters associated with the heating coil.

13. The system of claim 11, wherein desired temperature is a minimum temperature required to prevent condensation within the means for communicating.

14. The system of claim 11, further comprising

means for determining a flow rate of the pressurized flow of breathable gas;

and

means for determining the desired temperature for the means for communicating based on the determined flow rate.

15. The system of claim 11, further comprising one or more of a temperature sensor, a humidity sensor, an ambient temperature sensor, or an ambient humidity sensor removably coupled with the pressure support system.

18. The system of claim 11, wherein the physical characteristics of the patient circuit include one or more of the length of the patient circuit, or the surface area of the patient circuit.