TABLE 1.

Comparison between stationary and portable nasal nitric oxide analysers

Stationary analyser	Portable analyser
Gold standard	Not gold standard
Chemiluminescence detection	Electrochemical detection
Real-time analysis with visual display	End-point analysis with no visual display
Measurement taken from plateau of 3 s, enabling quality assurance	No visual display; potential for measurements from technically unacceptable manoeuvres
Calibration required	Internal standards apply, no calibration needed
Approximate costs	Approximate costs
€45 000–50 000 for the device	€3000–4000 for the device
€4200 for annual maintenance	Annual maintenance is not required
€15 per test (including nasal olive, catheter  and filters)	€15 per test (including nasal olive)