Endogenous nitric oxide in the nasal airways of healthy term newborn infants in Taiwan.

Background: Nitric oxide (NO) in the respiratory tract is an important regulator of pulmonary homeostasis during the perinatal transition. In humans, much of the nitric oxide is derived from the upper airways, and autoinhalation of nasal NO has been suggested to influence pulmonary function. No standard methods for measuring nasal NO in neonates currently exist, and previous studies have reported varying levels of nasal nitric oxide in infants, due to the different measuring methods used. The use of nasal olives with a central lumen placed securely in the nares was recommended as a standardized procedure for the measurement of nasal NO in adults and children in 1999. We attempted to establish a safe, convenient and practical method for measuring nasal NO in healthy newborn infants, and investigated possible correlations between nasal NO and gender, postnatal age, gestational age, birth weight, and the differences between the right and left nostrils.

Methods: Nasal NO was studied in healthy newborn infants within the first 3 postnatal days. Gas was sampled from the nostril, and NO concentrations were determined using a fast response chemiluminescence analyzer. Each newborn infant underwent NO measurements on the first, second and the third postnatal days. Ninety-one newborn infants completed the study.

Results: Peak nasal NO in 91 newborn infants was 42.52 +/- 16.82 (mean +/- SD) parts per billion (ppb) (right nostril) and 40.86 +/- 16.08 ppb (left nostril) on the first postnatal day, 48.75 +/- 17.64 ppb (right nostril) and 49.47 +/- 17.26 ppb (left nostril) on the second postnatal day, and 59.65 +/- 19.72 ppb (right nostril) and 59.29 +/- 20.09 ppb (left nostril) on the third postnatal day. Nasal NO increased significantly with postnatal age (p < 0.001). There were no significant differences in nasal nitric oxide between sexes, or in relation to gestational age or birth weight, or between left or right nostrils.

Conclusion: We conclude that nasal NO increased significantly in the first 3 days of life.