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Andrew B. Kairalla MD, Editor
 
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Target Ranges of Oxygen Saturation in Extremely Preterm Infants
SUPPORT Study Group of the Eunice Kennedy Shriver NICHD Neonatal Research Network
Published on-line at www.nejm.org May 16, 2010 (10.1056/NEJMoa0911781) .  http://tinyurl.com/2c4lvsq

Background.   Previous studies have suggested that the incidence of retinopathy is lower in preterm infants with exposure to reduced levels of oxygenation than in those exposed to higher levels of oxygenation. However, it is unclear what range of oxygen saturation is appropriate to minimize retinopathy without increasing adverse outcomes.

 Methods .  We performed a randomized trial with a 2-by-2 factorial design to compare target ranges of oxygen saturation of 85 to 89% or 91 to 95% among 1316 infants who were born between 24 weeks 0 days and 27 weeks 6 days of gestation. 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.

Results.   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.

Conclusions.   A lower target range of oxygenation (85 to 89%), as compared with a higher range (91 to 95%), did not significantly decrease the composite outcome of severe retinopathy or death, but it resulted in an increase in mortality and a substantial decrease in severe retinopathy among survivors. The increase in mortality is a major concern, since a lower target range of oxygen saturation is increasingly being advocated to prevent retinopathy of prematurity.

Comments:  Oh No!  Say it ain't so.  Could it be true that targeting Oxygen saturations in the high 80s INCREASES MORTALITY in VLBW babies?  I'm really not ready to accept that conclusion.  For the past decade or so, this has been one of our principle strategies for reducing CLD and ROP rates in these babies. 

 In an accompanying commentary  (http://tinyurl.com/2fvyq89), Dr Colin Morley reminds us that this result just barely reached statistical significance (p= 0.04),  and that no difference in survival was found is several previous studies (Tin  [Free Full Text],  Askie [Free Full Text], Chow  [Free Full Text]).  Dr Morley also points out that the actual oxygen saturation ranges achieved in this study were higher than targeted, especially in the low saturation group.  The unmasked trial data showed that the study actually compared saturation levels of about 89 to 97% (low saturation group) with saturation levels of 91 to 97%  (high saturation group).  It's hard for me to believe that this tiny difference in oxygen saturation ranges could be responsible for increasing mortality. 

So what should we do now?   Do we continue to accept oxygen saturations in the 80s for VLBW infants and possibly risk an increase in their mortality?  Or do we revert to keeping their oxygen saturations in the 90s risking more severe ROP and CLD?     Let's hear from those in the Respiratory Care group.   How about those of you who participated in previous respiratory focus groups (ReLi, Breathsavers, etc)?  Or anyone who has implemented an Oxygen With Love (OWL) protocol in thier NICU?  Should this study change our strategy about oxygen targeting?   Please chime in and let us know what you think. 

Andy Kairalla MD

Date: 06 Jul 2010
Time: 18:30:59

Really this article delivers a dilemma: what to do with oxygen? Which SO2 should be targeted? There is no easy answer. It seems to me there can be 2 possible ways of optimization of oxygen delivering: 1) still comparing SO2 with PO2 not allowing PO2 to rise too high as well as fall below 45 torr;   2) use another target SO2, for instance 87-90% which must be proven in the appropriate trial.

UserName: Yuriy Korzhynskyy
Institution: Danylo Halytskyy Lviv National Medical University, Lviv, Ukraine
telephone: +38032 2941624, mob +380505013399

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