Background

We aimed to investigate the effects of inhaled nitric oxide (iNO) on oxygenation and pulmonary artery pressure (PAP) in a randomised controlled trial of preterm infants.

Subjects

Infants were enrolled into the study at 96 hours of age if they were considered to be at high risk of developing chronic lung disease as determined by a risk prediction score.

Interventions/Methods

iNO was started at 20 ppm, reducing to a minimum of 5 ppm according to the response obtained. Parameters of oxygenation and ventilatory support were recorded. PAP was assessed using its inverse relationship with the acceleration time to right ventricular ejection time (AT/RVET) ratio. derived from the pulmonary artery Doppler waveform.

Results

20 infants were randomised to receive iNO and 22 acted as controls. Median birthweight (range) was 882 (416-1354)g for iNO group vs. 762 (520-1360)g for controls. Median gestational age was 27 weeks in both groups. There was a median fall in the oxygenation index (OI) of 17% within 30 minutes in treated infants (p < 0.01 vs controls); by 24 hours, the fall in OI was 27% (p = 0.04 vs controls). Median AT/RVET rose by 0.04 within 30 minutes of starting iNO therapy (p < 0.01 vs controls) and remained significantly different from controls until 4 hours.

Conclusions

iNO improves arterial oxygenation and lowers PAP in high risk preterm infants