1. Among critically ill patients receiving mechanical ventilation, differing oxygenation targets did not alter the number of ventilator-free days.

2. The risks of mortality and complications were similar across all studied oxygenation targets.

Evidence Rating Level: 1 (Excellent)

Study Rundown: A significant proportion of patients with critical illnesses require hospitalization and invasive mechanical ventilation. The mortality rate of hospitalized critically ill patients is up to 35%. In these patients, the fraction of inspired oxygen (FIO2) is adjusted to an arterial oxygenation saturation, as often measured by pulse oximetry (SpO2). Nevertheless, the optimal target for critically ill adult patients remains unclear, as there is a need to maintain adequate tissue oxygenation while minimizing the risk of hyperoxia and oxidative damage. The current study was a pragmatic trial examining the effect of lower (90%), intermediate (94%), and higher (98%) SpO2 targets on survival outcomes in critically ill adults receiving mechanical ventilation. By 28 days, no statistically significant differences were observed among the three groups in the number of days alive and free of mechanical ventilation. Furthermore, the incidences of complications were also similar among the groups. Although the single-center design may limit generalizability, it provided evidence demonstrating that varying oxygenation targets between low, intermediate, and high did not impact the survival and ventilator-free outcomes among critically ill adult patients.

Click here to read the study in NEJM

Relevant Reading: Lower or Higher Oxygenation Targets for Acute Hypoxemic Respiratory Failure

In-Depth [randomized controlled trial]: The present study is a pragmatic, open-label, cluster-crossover trial to investigate the impact of varying mechanical oxygenation targets on the survival outcomes of hospitalized patients with critical illnesses. Adult patients located in the medical intensive care unit (ICU) or the emergency department with planned admission to the ICU were enrolled when they first received invasive mechanical ventilation. Exclusion criteria were pregnancy and incarceration. Overall, 2,541 patients were randomized as clusters to lower (90%), intermediate (94%), or higher (98%) SpO2 targets. The primary outcome was the number of days alive and free of mechanical ventilation (or ventilator-free days) by day 28. The secondary outcome was death from any cause by day 28. Data censor occurred on day 28 or discharge, whichever occurred first. The median number of ventilator-free days was 20 (interquartile range [IQR], 0 to 25) in the lower-target group, 21 (IQR, 0 to 25) in the intermediate-target group, and 21 (IQR, 0 to 26) in the higher-target group (p=0.81). The mortality rate in the hospital was 34.8% in the lower-target group, 34% in the intermediate-target group, and 33.2% in the higher-target group. Incidences of complications including cardiac arrest, myocardial infarction, ischemic stroke, and pneumothorax were similar across groups. This trial added to the emerging evidence showing that varying oxygenation targets in critically ill adults did not influence survival outcomes.

Image: PD

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