Method for testing the function of a device
The function of a measuring device can be tested using a healthy person as an external control, provided that this person fulfils certain criteria and that particular method steps are adhered to.
1. A method of using a human control for testing the function of a device for measuring the concentration of a gaseous substance in exhaled air, the method comprising the steps of:
checking that said human control is in a normal condition,
measuring the concentration of said gaseous substance in air exhaled by said human control to obtain a current value,
determining if said current value of the measured concentration is within a specified range,
determining a reference value by calculating a moving average based on the current value and previously obtained values from measurements with the same human control,
determining the difference between said reference value and said current value, and
interpreting a deviation of more than a specified value as an indication that the device is malfunctioning.
2. The method according to claim 1 , wherein said specified range is adapted to the relevant diagnostic interval for the gaseous component to be determined.
3. The method according to claim 1 , wherein at least two measurement values from previous measurements are used when determining the moving average.
4. The method according to claim 1 , wherein at least three measurement values are used when determining the moving average.
5. The method according to claim 1 , wherein measurements are performed at an interval of at least 2 days but less than 8 days.
6. The method according to claim 1 , wherein said gaseous substance is chosen among carbon dioxide, oxygen, nitric oxide, and volatile organic compounds detectable in exhaled air.
7. The method according to claim 1 , wherein said gaseous substance is nitric oxide.
8. The method according to claim 1 , wherein the specified range for the current value is about 10 to about 40 ppb nitric oxide.
9. A method of using a human control for testing the function of a device for measuring the concentration of a gaseous substance in exhaled air, the method comprising the steps of:
checking that said human control is in a normal condition, wherein a human subject is considered to qualify as a control and as being in a normal condition when fulfilling the following criteria: no ongoing cold, no airway disease, no asthma, non-smoker, no allergy, no non-seasonal allergy, no intake of nitrate rich food within the last 3 hours, and no strenuous exercise performed within the last hour,
measuring the concentration of said gaseous substance in air exhaled by said human control to obtain a current value,
determining if said current value of the measured concentration is within a specified range,
determining a reference value,
determining the difference between said reference value and said current value, and
interpreting a deviation of more than a specified value as an indication that the device is malfunctioning.
10. The method according to claim 9 , wherein the interpretation of a deviation of more than a specified value as an indication that the device is malfunctioning is preceded by, and conditional to, an additional check that the control is in a normal condition.
11. The method according to claim 9 , wherein said specified range is adapted to the relevant diagnostic interval for the gaseous component to be determined.
12. The method according to claim 9 , wherein the reference value is determined by calculating a moving average based on the current value and previously obtained values from measurements with the same human control.
13. The method according to claim 12 , wherein at least two measurement values from previous measurements are used when determining the moving average.
14. The method according to claim 12 , wherein at least three measurement values are used when determining the moving average.
15. The method according to claim 12 , wherein measurements are performed at an interval of at least 2 days but less than 8 days.
16. The method according to claim 9 , wherein said gaseous substance is chosen among carbon dioxide, oxygen, nitric oxide, and volatile organic compounds detectable in exhaled air.
17. The method according to claim 9 , wherein said gaseous substance is nitric oxide.
18. The method according to claim 9 , wherein the specified range for the current value is about 10 to about 40 ppb nitric oxide.