LOW-DOSE INHALED NITRIC-OXIDE FOR NEONATES WITH PULMONARY-HYPERTENSION

Objective: Inhaled nitric oxide (iNO) has been shown to cause selectiv e pulmonary vasodilatation and improve ventilation-perfusion matching and may be an important therapeutic option for the treatment of persis tent pulmonary hypertension of the newborn (PPHN). We report our exper ience on the use of iNO in neonates with severe PPHN. Methodology: Inh aled NO was administered to 10 infants with PPHN and persistent hypoxa emia (meconium aspiration syndrome, n = 9; pneumonia, n = 1) after fai lure of conventional therapy to improve oxygenation. With the exceptio n of one infant, iNO was commenced at 10 ppm. Results: After 30 min ex posure to iNO, the arterial oxygen tension (PaO2) rose from a median o f 49 mmHg (6.5 kPa) [range 12-82 mmHg (1.6-10.9 kPa)] to 75 mmHg (10 k Pa) [range 17-450 mmHg (2.3-60 kPa)] (P = 0.005), while the median oxy genation index fell (pre-iNO of 37 vs post-iNO 20) (P = 0.005) and med ian systemic arterial pressure rose (pre-iNO 46.5 mmHg (6.2 kPa) [rang e 32-63 mmHg (4.3 to 8.4 kPa vs post-iNO 54.5 mmHg (7.3 kPa) [range 36 -74 kPa]) P = 0.005). All infants subsequently continued to receive iN O with the duration of exposure to iNO ranging from 12 to 168 h (media n duration 100 h). Three infants died despite showing an initial benef icial response to iNO. The mean duration of intubation for survivors w as 11.9 +/- 2.6 days. Methaemoglobinaemia and toxic levels of nitrogen dioxide were not seen during iNO administration. Of the seven survivo rs, 12 month follow up in two infants and 4 month follow up in four in fants showed age-appropriate neurodevelopmental skills, with one infan t having very mild hearing loss. Conclusions: Inhaled NO reduces the o xygenation index by improving the PaO, and decreasing ventilation pres sures, and appears to be clinically useful in severely hypoxaemic infa nts with PPHN refractory to conventional treatment.