Liberal Versus Restricted Indications for Oxygen in RDS: A Controlled Trial

Abstract

Oxygen therapy for RDS may improve the course of the syndrome by increasing pulmonary perfusion, improving myocardial, renal and cerebral function, and by preventing lactic acidosis. Conversely, it may aggravate the disease by pulmonary toxicity. In an attempt to assess the balance between benefits and risk, oxygen therapy for RDS was given during the first 72 h of life according to liberal indications in 75 infants (for PaO2 below 80 or PcapO2 below 55 mm Hg), and according to more restricted indications in 75 others (for PaO2 below 40 or PcapO2 below 35 mm Hg). The 2 groups were well matched and had a similar severity of RDS at 1 h of age. Concentrations of oxygen exceeding 60% ambient were required in 50% of liberal and 10% of restricted oxygen cases.Mortality was similar among the 45 infants weighing 500–1,250 g (68% liberal vs. 69% restricted). Infants weighing more than 1,250 g had a higher mortality when treated with liberal than with restricted oxygen (2% of 51 vs. 9% of 54). The liberal group developed more severe respiratory distress, more rales, faster respirations and more severe x-ray changes. Their pCO2 and lactic acid rose to higher levels and they required 30% more bicarbonate to maintain a blood pH of 7.35. Liberal oxygen as defined therefore, conferred no apparent benefit and caused significant pulmonary oxygen toxicity.