The Insight eNO System does NOT require inhalation of NO free air
Posted Dec 23 2009 10:25pm
Ambient Nitric Oxide
Nitric oxide in air constitutes what is called ‘ambient NO’. Most of the inhaled ambient NO enters the pulmonary blood by diffusion and binds to hemoglobin. The residual NO becomes part of the exhaled breath that only appears in the initial wash-out phase of a typical 11-second exhaled breath. Ambient NO is a function of the location, time of day etc. and can vary between 0 ppb and upwards of 200 ppb.
Exhaled NO (eNO) Profile
The exhaled nitric oxide (eNO) measurement profile of the Insight eNO System is characterized by an initial rise followed by a plateau. The Insight System analyzes nitric oxide sampled when the profile has reached the plateau which occurs during the last 4 sec of the exhalation breath maneuver. Nitric oxide (NO) is washed out in the initial phase and therefore does not affect the eNO readings obtained from the Insight System.
Studies Confirm Theory
A study was conducted where 12 subjects each performed 5 eNO tests preceded by inhalation of NO free air alternating with 5 eNO tests preceded by inhalation of air containing a 200 ppb concentration of nitric oxide (NO). Testing based on these 120 measurements shows that the overall impact of high ambient NO on the results from the Insight System is statistically insignificant (0.8 ppb). This result is consistent with a landmark publication2confirming that the eNO results when sampled properly do not get affected by ambient NO.