Oxygen requirement as a screening tool for the detection of late pulmonary hypertension in extremely low birth weight infants

Background: Many extremely low birth weight infants develop pulmonary hypertension late in their clinical course, and over 60% go undetected by early screening echocardiography. At present, no standardised screening protocol exists for detecting late pulmonary hypertension in extremely low birth weight infants. We assessed the utility of oxygen supplementation as a predictor of late pulmonary hypertension. Methods: A retrospective single-centre review of extremely low birth weight infants with no evidence of CHD and those surviving for >30 days was performed. The association between oxygen >= 30% at day of life 30 and diagnosis of late pulmonary hypertension was estimated with an odds ratio and 95% confidence interval using logistic regression. Doppler echocardiography was used to diagnose pulmonary hypertension in the infants. Results: A total of 230 infants met the study criteria. The incidence of late pulmonary hypertension was 8.3% (19/230). Infants with late pulmonary hypertension were more likely to have a lower mean birth weight (667.1 +/- 144 versus 799.3 +/- 140 g, p = 0.001) and more likely to be small for gestational age (47.4 versus 14.2%, p = 0.004). Oxygen requirement >= 30% at day of life 30 was associated with increased risk of late pulmonary hypertension (odds ratio = 3.77, 95% confidence interval = 1.42-10.00, p = 0.008) in univariate analysis and after adjusting for birth weight (odds ratio = 2.47, 95% confidence interval = 0.89-6.84, p = 0.08). Conclusions: The need of oxygen supplementation. 30% at day of life 30 may be a good screening tool for detecting late pulmonary hypertension in extremely low birth weight infants.