Target Oxygen Saturation in Extreme Prems

1316 infants who were born between 24 weeks 0 days and 27 weeks 6 days of gestation were randomised to one of two different target ranges of oxygen saturation: 85 – 89% vs. 91 – 95%. The primary outcome was a composite of severe retinopathy of prematurity (defined as the presence of threshold retinopathy, the need for surgical ophthalmologic intervention, or the use of bevacizumab), death before discharge from the hospital, or both.

All infants were also randomly assigned to continuous positive airway pressure or intubation and surfactant in a 2-by-2 factorial design.

The rates of severe retinopathy or death did not differ significantly between the lower-oxygen-saturation group and the higher-oxygen-saturation group (28.3% and 32.1%, respectively; relative risk with lower oxygen saturation, 0.90; 95% confidence interval [CI], 0.76 to 1.06; P=0.21). Death before discharge occurred more frequently in the lower-oxygen-saturation group (in 19.9% of infants vs. 16.2%; relative risk, 1.27; 95% CI, 1.01 to 1.60; P=0.04), whereas severe retinopathy among survivors occurred less often in this group (8.6% vs. 17.9%; relative risk, 0.52; 95% CI, 0.37 to 0.73; P<0.001). There were no significant differences in the rates of other adverse events.

An editorial notes that the unmasked trial data showed that the distribution of oxygen saturation levels was within or above the target range in the higher-oxygen-saturation group, but in the lower-oxygen-saturation group, it was about 90 to 95% (i.e., above the target range). The difference in oxygen saturation levels between the groups was about 3 percentage points instead of the 6 percentage points that had been planned. Therefore, this study actually compared saturation levels of about 89 to 97% with saturation levels of 91 to 97%; the results should be ascribed to these higher ranges.

Targeting oxygen saturation levels is difficult, and a recommended oxygen saturation range that is effective yet safe remains elusive. A lower oxygen saturation level significantly reduces the incidence of severe retinopathy of prematurity but may increase the rate of death.

Target Ranges of Oxygen Saturation in Extremely Preterm Infants
N Engl J Med. 2010 May 16. [Epub ahead of print]