Severity of Impaired Oxygenation and Conservative Oxygenation Targets in Mechanically Ventilated Children: A Post Hoc Subgroup Analysis of the Oxy-PICU Trial of Conservative Oxygenation

Objectives: A conservative oxygenation strategy is recommended in adult and pediatric guidelines for the management of acute respiratory distress syndrome to reduce iatrogenic lung damage. In the recently reported Oxy-PICU trial, targeting peripheral oxygen saturations (Spo2) between 88% and 92% was associated with a shorter duration of organ support and greater survival, compared with Spo2 greater than 94%, in mechanically ventilated children following unplanned admission to PICU. We investigated whether this benefit was greater in those who had severely impaired oxygenation at randomization.

Design: Post hoc analysis of a pragmatic, open-label, multicenter randomized controlled trial.

Setting: Fifteen PICUs across England and Scotland.

Patients: Children between 38 weeks old corrected gestational age and 15 years accepted to a participating PICU as an unplanned admission and receiving invasive mechanical ventilation with supplemental oxygen for abnormal gas exchange.

Interventions: A mixed-effects ordinal regression model was used to explore the effect of severity of lung injury, dichotomized to an oxygen saturation index (OSI) less than 12 or greater than or equal to 12 at randomization, the trial group allocation, age, and Pediatric Index of Mortality-3 on the composite ordinal outcome measure of duration of organ support at day 30 and mortality, with death being the worst outcome. An interaction term was included to specifically understand the effect of trial arm allocation on those with and OSI less than 12 and OSI greater than or equal to 12.

Measurements and main results: Data were available for 1775 of 1986 eligible children. Two hundred twelve of 1775 children had an OSI greater than or equal to 12 at randomization. The trial primary outcome did not vary significantly according to OSI category. Both children with OSI less than 12 (odds ratio [OR], 0.85; 95% CI, 0.71-1.01) and OSI greater than or equal to 12 (OR, 0.95; 95% CI, 0.49-1.84) benefited from conservative arm allocation, with relative benefit greater for those with an OSI less than 12.

Conclusions: These data do not provide evidence that a conservative oxygenation strategy should be limited to mechanically ventilated children with severely impaired oxygenation.