Apparatus and method for diagnostic gas analysis
A handheld, small but accurate and reliable device for diagnostic NO measurements using a NO sensor, where the parameters governing the taking of the sample are different from the parameters optimal for the accuracy of said NO sensor. By temporarily storing a portion of the exhaled air, and feeding this to the sensor at a flow rate adapted to the NO sensor, the accuracy and sensitivity of a system/method involving NO sensors, in particular electrochemical NO sensors, can be increased. The method for diagnostic NO measurements comprises steps for controlling the inhalation of NO free air, as well as the exhalation, both by built-in means and by audible and/or visual feedback to the patient.
1. A method for handling a sample of exhaled air in a device for diagnostic NO measurements, the device including a NO sensor and a pump or a fan, comprising:
collecting a sample of exhaled air during an exhalation performed by a person at a controlled flow rate and pressure;
feeding the collected sample with the pump or the fan to the NO sensor at a flow rate suitable for said sensor, the feeding performed for a duration longer than the duration of said exhalation;
determining an NO concentration in said sample; and
wherein NO-free air is supplied to the person prior to the exhalation into the device.
2. The method according to claim 1 , wherein the NO-free air is supplied to the person by way of an NO-scrubber included in the device, prior to exhalation into the device.
3. The method according to claim 1 , wherein audible or visual feedback is given to the person during an inhalation preceding the exhalation and during the exhalation, in order to support valid NO concentration determination.
4. The method according to claim 1 , wherein the exhalation flow rate is controlled to a value of about 20 to 800 ml/s.
5. The method according to claim 1 , wherein said NO sensor is an electrochemical sensor.
6. The method according to claim 1 , wherein the sample is fed to the sensor at a flow rate different from the exhalation flow rate.
7. The method according to claim 1 , wherein the sample is fed to the sensor at a flow rate lower than the exhalation flow rate.
8. The method according to claim 1 , wherein the sample of exhaled air is input to the device into a buffer chamber, and the pump or the fan feeds the sample from the buffer chamber to the NO sensor.
9. The method according to claim 8 , wherein the sample is temporarily kept in said buffer chamber.
10. The method according to claim 1 , further comprising receiving data regarding the person at the device, the data including at least one of:
information relating to the person's medications, or
assessment of the person's state of health.
11. A non-transitory computer readable medium storing logical instructions for controlling the device to perform the steps of claim 1 .
12. A method for measuring exhaled NO with a device that includes an NO sensor and a pump or a fan, comprising:
collecting a sample of exhaled air at a first preset flow rate and pressure and temporarily storing the collected sample;
feeding the stored sample with the pump or the fan to said NO sensor at a second preset flow rate and pressure suitable for said sensor;
determining an NO concentration in said sample; and
wherein NO-free air is supplied to the person prior to the exhalation into the device.
13. The method according to claim 12 , wherein the NO-free air is supplied to the person by way of an NO-scrubber included in the device, prior to exhalation into the device.
14. The method according to claim 12 , wherein audible or visual feedback is given to the person during an inhalation preceding the exhalation and during the exhalation, in order to support valid NO concentration determination.
15. The method according to claim 12 , wherein said first preset flow rate is controlled to a value of about 20 to 800 ml/s.
16. The method according to claim 12 , wherein the sample of exhaled air is temporarily stored in a buffer chamber, and fed to the NO sensor from the buffer chamber by a pump or a fan.
17. The method according to claim 12 , wherein said NO sensor is an electrochemical sensor.
18. A non-transitory computer readable medium storing logical instructions for controlling the device to perform the steps of claim 12 .