REPETITIVE MEASUREMENT OF EXHALED NITRIC OXIDE IN NEWBORNS. ASSESMENT OF DIURNAL VARIABILITY
  Basek P., 2Moeller A., 2Bernet V., 2Wildhaber J., NICU University Hospital Hradec Kralove, Czech Republic, 2 Swiss Paediatric Respiratory Research Group, University Children’s Hospital Zurich, Switzerland
 

Background: Exhaled nitric oxide (eNO) has been found to be a useful non-invasive marker, which is in relation to airway inflammation. Increased levels of eNO have been widely documented in patients with asthma and atopy. Recent studies shown, that exhaled nitric oxide levels are elevated in infants with bronchopulmonary dysplasia. The measurement of eNO involves the patient maintaining a constant expiratory flow against an external resistor. Newborns and infants are an inherently uncooperative population and hence are unable to maintain constant expiratory flows. The multiple-breath method allows measurement of eNO during spontaneous tidal breathing and could be applied even in newborns.

Aims: In our study we tested the feasibility of repetitive measurement of eNO in newborns using multiple-breath technique. Beside this we assessed the diurnal variability in nitric oxide production.

Patients and Methods: 10 non-sedated newborns without any respiratory problem were enrolled in this study. The mean postnatal age was 16 days (range 7 -23). Measurements were performed repetitively within the 24-hour period in each infant. For the measurement a facemask was placed over the infant s mouth and nose and NO was measured in exhaled air. A bias flow of NO-free air from ventilator with NO scavenger was passed through the mask. A sampling catheter was placed in the tubing leading directly to the mask and was attached to the analyser (Ecomedics, Switzerland). The analyser allows continuous, simultaneous measurement and display of NO values, flow rate and volume of the exhaled breath. Using special software program the expiratory plateau fraction of eNO could be also reported.

Mean Results: The mean of eNO in our group of newborns was 15.6 ppb (range 11.2 -28.8). Using One Way Analysis of Variance on Ranks we could not demonstrate any diurnal pattern of eNO ( p = 0,98).

Conclusion: The multiple-breath method allows a non-invasive, real-time analysis of eNO in non-sedated newborns. During repeated measurements in a 24-hour period we did not show any pattern of eNO, so the NO production seems not to be affected by circadian rhythm in healthy newborns.