Method, arrangement and computer program product for respiratory gas monitoring of ventilated patients

Patent metadata

Field	Value
Publication number	US-8985107-B2
Application number	US-201213406621-A
Country	US
Kind code	B2
Filing date	Feb 28, 2012
Priority date	Feb 28, 2012
Publication date	Mar 24, 2015
Grant date	Mar 24, 2015

Abstract

A method, device, and computer program product for improving accuracy of a respiratory gas measurement from a subject ventilated at a predetermined respiration rate through a ventilator. A respiratory gas measurement value is acquired within a first expiration period of the subject, thereby to obtain a first measurement value. The ventilator is paused for a pause period within a second expiration period of the subject and a respiratory gas measurement is performed within the pause period, thereby to obtain a second measurement value. A correction factor is then determined based on the first measurement value and the second measurement value and the correction factor is employed to correct subsequent respiratory gas measurement values obtained from the subject at the predetermined respiration rate, thereby to improve the accuracy of the measurement.

First claim

The invention claimed is:

1. A method for improving accuracy of a respiratory gas measurement from a ventilated subject, the method comprising:
ventilating a subject at a predetermined respiration rate through a ventilator;
acquiring a respiratory gas measurement value within a first expiration period of the subject, thereby to obtain a first measurement value;
pausing the ventilator for a pause period within a second expiration period of the subject;
performing a respiratory gas measurement within the pause period, thereby to obtain a second measurement value;
determining a correction factor based on the first measurement value and the second measurement value; and
using the correction factor to correct subsequent respiratory gas measurement values obtained from the subject at the predetermined respiration rate.

2. The method according to claim 1 , further comprising measuring respiratory gas values during successive expiration periods of the subject, thereby to obtain a time series of respiratory gas values, wherein the acquiring includes selecting a respiratory gas value from the time series.

3. The method according to claim 2 , wherein the selecting, includes selecting the latest respiratory gas value from the time series, and wherein the pausing is initiated in response to the selecting.

4. The method according to claim 1 , wherein the determining includes determining the correction factor, in which the correction factor represents a ratio of the first and second measurement values.

5. The method according to chum 1 , further comprising repeating the acquiring, pausing, performing, determining and using when a predetermined event occurs, in which the predetermined event is one of a change in respiration rate of the subject and a change in mean airway pressure of the subject.

6. The method according to claim 5 , further comprising defining a correction curve based on a plurality of data points, wherein each data point comprises a correction factor and respective respiration rate and wherein the correction curve indicates a correction factor for any new respiration rate.

7. The method according to claim 5 , wherein the defining comprises using n th order regression to produce a fitting curve that fits to the plurality of data points, wherein the fitting curve represents the correction curve.

8. The method according to claim 1 , wherein the acquiring includes acquiring the first measurement value and the performing includes obtaining the second measurement value, in which the first measurement value and the second measurement value represent carbon dioxide concentrations.

9. An arrangement for improving accuracy of a respiratory gas measurement from a ventilated subject, the arrangement comprising:
a ventilator unit adapted to ventilate a subject at a predetermined respiration rate;
a measurement unit adapted to acquire a respiratory gas measurement value within a first expiration period of the subject, thereby to obtain a first measurement value;
a ventilator control unit adapted to pause the ventilator unit for a pause period within a second expiration period of the subject;
wherein the measurement unit is further adapted to perform a respiratory gas measurement within the pause period, thereby to obtain a second measurement value; and
a ventilator processing unit adapted to determine a correction factor based on the first measurement value and the second measurement value and to use the correction factor to correct subsequent respiratory gas measurement values obtained from the subject at the predetermined respiration rate.

10. The arrangement according to claim 9 , wherein the measurement unit is further adapted to
measure respiratory gas values during successive expiration periods of the subject, thereby to obtain a time series of respiratory gas values; and
acquire the first measurement value by selecting a respiratory gas value from the time series.

11. The arrangement according to claim 10 , wherein the measurement unit is adapted to select the latest respiratory gas value from the time series, and wherein the ventilator control unit is adapted to pause the ventilator unit in response to selection of the latest respiratory gas value.

12. The arrangement according to claim 9 , wherein the correction factor represents a ratio of the first and second measurement values.

13. The arrangement according to claim 9 , wherein the ventilator control unit is adapted to initiate determination of a new correction factor when a predetermined event occurs, in which the predetermined event is one of a change in respiration rate of the subject and a change in mean airway pressure of the subject.

14. The arrangement according to claim 13 , wherein the ventilator processing unit is further adapted to define a correction curve based on a plurality of data points, wherein each data point comprises a correction factor and a respective respiration rate and wherein the correction curve indicates a correction factor for any new respiration rate.

15. The arrangement according to claim 14 , wherein the ventilator processing unit is adapted to use n th order regression to produce a fitting curve that fits to the plurality of data points, wherein the fitting curve represents the correction curve.

16. The arrangement according to claim 9 , wherein the first and second measurement values represent carbon dioxide concentrations.

Assignees

• Viertiö-Oja Hanna
• Coffeng Rene
• Gen Electric

Inventors

• Viertiö-Oja Hanna
• Coffeng Rene

Classifications

• A61B5/0816

  Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00) · CPC title

• A61B5/72

  Signal processing specially adapted for physiological signals or for diagnostic purposes · CPC title

• A61M2230/435

  partial O2 pressure (P-O2) · CPC title

• A61M16/1055

  bacterial · CPC title

• A61B5/0836 Primary

  Measuring rate of CO2 production · CPC title