Response to Inhaled Nitric Oxide and Clinical Outcome in Very Low Birth Weight Infants with Early Pulmonary Hypertension

Abstract

Purpose To determine the efficacy of inhaled nitric oxide (iNO) in very low birth weight (VLBW) infants with early pulmonary hypertension (PH). Methods We reviewed the medical records of 22 preterm infants who were born 2 >20% and/or oxygenation index (OI) >20% from the baseline values at 1 hour after beginning iNO therapy. Cardiorespiratory support indices including OI, oxygen saturation index, and vasoactive-inotropic score (VIS) were serially obtained for 96 hours following iNO therapy. Results The mean gestational age of the patients was 26.1±2.0 weeks and the mean birth weight was 842±298 g. The mean OI at the start of iNO was 63.8±61.0. Improvement in oxygenation indicated by prompt decrease in FiO2 and OI from the baseline values were observed 1 hour after beginning iNO therapy and lasted up to 96 hours. After iNO therapy, VIS increased until 24 hours and decreased thereafter. At 1 hour after iNO, 16 patients (73%) were classified as responders and six (27%) as nonresponders. Compared with nonresponders, responders did not demonstrate the beneficial effect of iNO in terms of short-term survival and neonatal complications. The 1-year mortality rate did not differ between responders (56%) and nonresponders (67%). Conclusion Although iNO treatment immediately improved oxygenation in most VLBW infants with early severe PH, the long-term mortality rate was high. A largescale study is needed to determine whether the initial response to iNO can predict patients’ survival.

Keywords

• infant, very low birth weight
• hypertension, pulmonary
• nitric oxide