Inhaled nitric oxide in persistent pulmonary hypertension of the newborn: four-year experience in a single medical center.

Forty-eight infants with persistent pulmonary hypertension of the newborn (PPHN) from July, 1997 to June, 2001 were enrolled for a prospectively study to determine the role of inhaled nitric oxide (NO) treatment and to determine an appropriate weaning strategy of NO. The initial dose of NO was started at 10 ppm for 10 minutes. If the infant's symptoms did not improve, we used a rapid dose ladder schedule for increasing the dose of NO to 20, 40 and 80 ppm every 10 minutes until we achieved the desired response. When oxygenation improved for 30 minutes, NO was decreased by 5 ppm every 10 minutes until reaching 5 ppm which was maintained for 2-3 hours. During the NO weaning period, if the SpO2 decreased by 10% or fell below 85%, the NO was increased to the previous higher dose and maintained this lowest effective dose for 2-3 hours. During this period, FiO2 was decreased by 10% every 10 minutes and peak inspiratory pressure was decreased gradually as the infant tolerable to avoid a decrease in saturation; we then tried to repeat the weaning procedure of NO. Inhaled NO was discontinued at 5 ppm if the infants were stable for 2-3 hours, and at the same time FiO2 was permitted to raise 10-20%. If SpO2 decreased by 10% or fell below 85% within 5 minutes, NO was reinstated at 5 ppm. A second attempt at weaning NO was made 2-3 hours later when the infants were stable. Thirty-four infants (70.8%) survived. Forty infants (83.3%), including 34 who survived and 6 who died, had good responses to inhaled NO. The mean effective NO concentration was 37 (5-80) ppm. The mean duration of inhaled NO treatment was 43 (6-153) hours. This study has demonstrated that inhaled NO is an effective rescue treatment for infants with severe PPHN, but the final outcome of infants depends not only on the response to inhaled NO but also on the associated complications. Using our weaning strategy, we shortened the duration of inhaled NO treatment as compared with a previous study (43 vs. 87 hours). Beginning inhaled NO therapy early in severe PPHN may be an important factor in shortening the duration of NO therapy. Further controlled trials of this weaning strategy are warranted.