Linking Hyperoxia and Harm: Consequence or Merely Subsequence?

Pao2 and Mortality in Neonatal Extracorporeal Membrane Oxygenation: Retrospective Analysis of the Extracorporeal Life Support Organization Registry, 2015-2020

OBJECTIVES

Extracorporeal life support can lead to rapid reversal of hypoxemia but the benefits and harms of different oxygenation targets in severely ill patients are unclear. Our primary objective was to investigate the association between the Pao2 after extracorporeal membrane oxygenation (ECMO) initiation and mortality in neonates treated for respiratory failure.

DESIGN

Retrospective analysis of the Extracorporeal Life Support Organization (ELSO) Registry data, 2015-2020.

PATIENTS

Newborns supported by ECMO for respiratory indication were included.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Pao2 24 hours after ECMO initiation (H24 Pao2) was reported. The primary outcome was 28-day mortality. We identified 3533 newborns (median age 1 d [interquartile range (IQR), 1-3]; median weight 3.2 kg [IQR, 2.8-3.6]) from 198 ELSO centers, who were placed on ECMO. By 28 days of life, 731 (20.7%) had died. The median H24 Pao2 was 85 mm Hg (IQR, 60-142). We found that both hypoxia (Pao2 < 60 mm Hg) and moderate hyperoxia (Pao2 201-300 mm Hg) were associated with greater adjusted odds ratio (aOR [95% CI]) of 28-day mortality, respectively: aOR 1.44 (95% CI, 1.08-1.93), p = 0.016, and aOR 1.49 (95% CI, 1.01-2.19), p value equals to 0.045.

CONCLUSIONS

Early hypoxia or moderate hyperoxia after ECMO initiation are each associated with greater odds of 28-day mortality among neonates requiring ECMO for respiratory failure.

Editor's Choice Articles for September

The September 2023 issue and this year has already proven to be important for improving our understanding of pediatric acute respiratory distress syndrome (PARDS); Pediatric Critical Care Medicine (PCCM) has published 16 articles so far. Therefore, my three Editor's Choice articles this month highlight yet more PCCM material about PARDS by covering the use of noninvasive ventilation (NIV), the trajectory in cytokine profile during illness, and a new look at lung mechanics. The PCCM Connections for Readers give us the opportunity to focus on some clinical biomarkers of severity and mortality risk during critical illness.

Association of Arterial Hyperoxia With Outcomes in Critically Ill Children: A Systematic Review and Meta-analysis

IMPORTANCE

Oxygen supplementation is a cornerstone treatment in pediatric critical care. Accumulating evidence suggests that overzealous use of oxygen, leading to hyperoxia, is associated with worse outcomes compared with patients with normoxia.

OBJECTIVES

To evaluate the association of arterial hyperoxia with clinical outcome in critically ill children among studies using varied definitions of hyperoxia.

DATA SOURCES

A systematic search of EMBASE, MEDLINE, Cochrane Library, and ClinicalTrials.gov from inception to February 1, 2021, was conducted.

STUDY SELECTION

Clinical trials or observational studies of children admitted to the pediatric intensive care unit that examined hyperoxia, by any definition, and described at least 1 outcome of interest. No language restrictions were applied.

DATA EXTRACTION AND SYNTHESIS

The Meta-analysis of Observational Studies in Epidemiology guideline and Newcastle-Ottawa Scale for study quality assessment were used. The review process was performed independently by 2 reviewers. Data were pooled with a random-effects model.

MAIN OUTCOMES AND MEASURES

The primary outcome was 28-day mortality; this time was converted to mortality at the longest follow-up owing to insufficient studies reporting the initial primary outcome. Secondary outcomes included length of stay, ventilator-related outcomes, extracorporeal organ support, and functional performance.

RESULTS

In this systematic review, 16 studies (27 555 patients) were included. All, except 1 randomized clinical pilot trial, were observational cohort studies. Study populations included were post-cardiac arrest (n = 6), traumatic brain injury (n = 1), extracorporeal membrane oxygenation (n = 2), and general critical care (n = 7). Definitions and assessment of hyperoxia differed among included studies. Partial pressure of arterial oxygen was most frequently used to define hyperoxia and mainly by categorical cutoff. In total, 11 studies (23 204 patients) were pooled for meta-analysis. Hyperoxia, by any definition, showed an odds ratio of 1.59 (95% CI, 1.00-2.51; after Hartung-Knapp adjustment, 95% CI, 1.05-2.38) for mortality with substantial between-study heterogeneity (I2 = 92%). This association was also found in less heterogeneous subsets. A signal of harm was observed at higher thresholds of arterial oxygen levels when grouped by definition of hyperoxia. Secondary outcomes were inadequate for meta-analysis.

CONCLUSIONS AND RELEVANCE

These results suggest that, despite methodologic limitations of the studies, hyperoxia is associated with mortality in critically ill children. This finding identifies the further need for prospective observational studies and importance to address the clinical implications of hyperoxia in critically ill children.