Zone heating for respiratory circuits

Patent metadata

Field	Value
Publication number	US-10960167-B2
Application number	US-201615758714-A
Country	US
Kind code	B2
Filing date	Sep 9, 2016
Priority date	Sep 9, 2015
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

Some embodiments provide for an inspiratory limb for a breathing circuit that includes a first segment that comprises a first heater wire circuit and a second segment that comprises a second heater wire circuit. The inspiratory limb can include an intermediate connector that includes a connection circuit that electrically couples the first heater wire circuit to the second heater wire circuit. The inspiratory limb can be configured to operate in two modes wherein, in a first mode, electrical power passes through the first electrical connection to provide power to the first heater wire circuit without providing power to the second heater wire circuit, and in a second mode, electrical power pass through the first electrical connection to provide power to both the first heater wire circuit and the second heater wire circuit.

First claim

What is claimed is:

1. A respiratory humidification system comprising:
an inspiratory limb including a first segment with a first heater wire, a second segment with a second heater wire, and a temperature sensor positioned at a patient end of the second segment for measuring a patient end parameter, wherein the first and second heater wires are electrically coupled, the first heater wire forming a first heater circuit and the first and second heater wires forming a second heater circuit, the first and second heater wires configured to heat respiratory gases passing through the inspiratory limb; and
a flow sensor in a flow path of the system and configured to measure a flow rate of the respiratory gases;
wherein the first and second heater wires and the temperature and flow sensors are configured to be in electrical communication with a hardware processor configured to execute software instructions which cause the processor to control the first and second heater circuits, wherein, when a difference between an output of the temperature sensor and a patient end parameter set point is below a predetermined error threshold, the processor is configured to heat the respiratory gases using the first heater circuit until a maximum temperature is reached in the first heater wire, and when the difference between the output of the temperature sensor and the patient end parameter set point is at or above the predetermined error threshold, the processor is configured to heat the respiratory gases using the second heater circuit, and
wherein a maximum power provided to the first heater circuit is a first maximum value or a second maximum value based on the flow rate, the first maximum value higher than the second maximum value.

2. The respiratory humidification system of claim 1 , wherein the maximum power is the first maximum value when the measured flow rate is higher than a flow rate threshold, and the maximum power is the second maximum value when the measured flow rate is below the flow rate threshold.

3. The respiratory humidification system of claim 2 , wherein the flow rate threshold is between about 2.4 lpm and about 5 lpm.

4. The respiratory humidification system of claim 2 , wherein the flow rate threshold is about 3.5 lpm.

5. The respiratory humidification system of claim 1 , wherein when the first maximum power is being provided to the first heater circuit and the measured flow rate decreases to a high flow to low flow threshold, the maximum power provided to the first heater circuit switches to the second maximum power, and when the second maximum power is being provided to the first heater circuit and the flow rate increases to a low flow to high flow threshold, the maximum power provided to the first heater circuit switches to the first maximum power, the high flow to low flow threshold being lower than the low flow to high flow threshold.

6. The respiratory humidification system of claim 5 , wherein the high flow to low flow threshold is between about 2.4 lpm and about 5 lpm.

7. The respiratory humidification system of claim 5 , wherein the low flow to high flow threshold is about 6.5 lpm.

8. The respiratory humidification system of claim 5 , wherein a portion of the first segment of the inspiratory limb that is adjacent to the second segment is exposed to the same ambient environment as the second segment.

9. The respiratory humidification system of claim 8 , wherein the portion of the first segment and the second segment are inside an incubator and a remaining portion of the first segment is outside the incubator.

10. A respiratory humidification system comprising:
an inspiratory limb including a first segment with a first heater wire, a second segment with a second heater wire, and a temperature sensor positioned at a patient end of the second segment for measuring a patient end parameter, wherein the first and second heater wires are electrically coupled, the first heater wire forming a first heater circuit and the first and second heater wires forming a second heater circuit, the first and second heater wires configured to heat respiratory gases passing through the inspiratory limb; and
a flow sensor in a flow path of the system and configured to measure a flow rate of the respiratory gases;
a controller in electrical communication with the first and second heater wires and the temperature and flow sensors and configured to control the first and second heater circuits, wherein, when a difference between an output of the temperature sensor and a patient end parameter set point is below a predetermined error threshold, the controller is configured to heat the respiratory gases using the first heater circuit until a maximum temperature is reached in the first heater wire, and when the difference between the output of the temperature sensor and the patient end parameter set point is at or above the predetermined error threshold, the controller is configured to heat the respiratory gases using the second heater circuit, and
wherein when a measured flow rate is at or below a predetermined flow rate threshold, the controller is configured to control a duty cycle or power supplied to one or both of the first heater circuit or the second heater circuit using a first heater circuit low flow cap or limit and/or a second heater circuit low flow cap or limit to prevent a surface temperature of a portion of the first segment of the inspiratory limb adjacent the second segment of the inspiratory limb from exceeding a surface temperature threshold.

11. The respiratory humidification system of claim 10 , wherein the second heater circuit low flow cap or limit for the duty cycle or power supplied to the second heater circuit is 70% of a maximum available power deliverable by drive circuits.

12. The respiratory humidification system of claim 10 , wherein the first heater circuit low flow cap or limit for the duty cycle or power suppled to the first heater circuit is 37% of a maximum available power deliverable by drive circuits.

13. The respiratory humidification system of claim 10 , wherein the controller is configured to determine:
a duty cycle or power supplied to the second heater circuit needed to bring the system to the patient end parameter set point; and
a maximum duty cycle or power supplied to the first heater circuit using the determined duty cycle or power supplied to the second heater circuit and the low flow cap or limit for the duty cycle or power supplied to the first heater circuit.

14. The respiratory humidification system of claim 13 , wherein the controller is further configured to determine a duty cycle or power supplied to the first heater circuit needed to bring the system to the patient end parameter set point, wherein the determined duty cycle or power supplied to the first heater circuit is inversely related to the determined duty cycle or power supplied to the second heater circuit.

15. The respiratory humidification system of claim 13 , wherein the controller is further configured to determine a duty cycle or power supplied to the first heater circuit needed to bring the system to the patient end parameter set point, wherein when the determined duty cycle or power supplied to the second heater circuit is less than the second heater circuit low flow cap or limit, the determined duty cycle or power supplied to the first heater circuit corresponds to a difference between the second heater circuit low flow cap or limit and the determined duty cycle or power supplied to the second heater circuit.

16. The respiratory humidification system of claim 10 , wherein when the first heater circuit is h

Assignees

• Fisher & Paykel Healthcare Ltd

Inventors

• Liu Po-Yen
• Seekup Peter Alan
• Newland Anthony James
• Smith Malcolm David
• Si Ping
• Oosthuysen Helgard
• Wilson Matthew Robert
• Kwan Ian Lee Wai
• Alnashi Sinaa
• Tonkin Paul James
• Mccool Kiel Anthony
• Kemps David Robert
• Lin Yayi
• Ross Callum Mcdonald
• Sims David John

Classifications

• A61M2205/50

  with microprocessors or computers · CPC title

• A61M2205/3653

  by Joule effect, i.e. electric resistance · CPC title

• A61M2205/3368

  Temperature · CPC title

• A61M2205/3327

  Measuring · CPC title

• A61M2205/18

  with alarm · CPC title