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👉In a very well-designed study, Matthew W. Semler et al. addressed this critical question.

👉They investigated the effects of lower, intermediate, and higher SpO₂ targets on clinical outcomes among critically ill adults receiving mechanical ventilation.

👉They evaluated three ranges of SpO₂ targets in intubated patients:

• lower SpO₂ target (90%; goal range, 88 to 92%),
• intermediate SpO₂ target (94%; goal range, 92 to 96%)
• higher SpO₂ target (98%; goal range, 96 to 100%)

👉It was a pragmatic, cluster-randomized, cluster-crossover trial conducted in the emergency department and medical intensive care unit at a single center (the Vanderbilt University Medical Center) from 2018 to 2021 (36 months of enrollment).

👉Inclusion criteria were adults (≥18 years of age) in the medical ICU or the ED at the time of the first receipt of invasive mechanical ventilation. In addition, patients were excluded if they were pregnant or incarcerated. Covid-19 patients were not included.

👉Intervention:

• FIO₂ was adjusted to maintain SpO₂ within the target range.
• SpO₂ was assessed using continuous pulse oximetry, with an alarm set for values lower or higher than the goal range. 

👉Results:

• 2987 patients were included from a total of 3024 eligible patients (exclusion of 1.2%).  From these, 2541 (85%) were included in the primary analysis: 808 (31.8%) to the lower-target group, 859 (33.8%) to the intermediate-target group, and 874 (34.4%) to the higher-target group. The groups had similar characteristics at baseline.
•  More than 7 million SpO₂ and FIO₂ values were measured between enrollment and cessation of invasive MV as they were sampled were automatically extracted from the bedside monitor at a frequency of every 1 minute!
•  There were no statistically significant differences for the primary outcome, ventilator-free days, nor for the secondary one, mortality. Figure below

• At 28 days, 281 patients (34.8%) in the lower target group, 292 patients (34.0%) in the intermediate-target group, and 290 patients (33.2%) in the higher-target group had died before hospital discharge.
• The incidences of cardiac arrest, arrhythmia, myocardial infarction, ischemic stroke, and pneumothorax or pneumomediastinum were similar in the three groups. In subgroup analysis (patients with cardiac arrest, ARDS, acute myocardial infarction, sepsis/septic shock, and receipt of vasopressor no significant differences were found.

😎Strengths. The study is outstanding in evaluating three different targets for SpO₂. Furthermore, it was very well designed and powered to detect meaningful differences among the three groups.

😓 Limitations: It is a single-center study reducing its generalizability. It did not evaluate the long-term effects of the three ranges of SpO₂.

🧐 Our opinion: It provides robust evidence that, within the range of SpO₂ from 90 to 98%, the choice of oxygen target does not affect short-term important clinical outcomes for a broad population of critically ill adults. It seems reasonable to choose levels around 92 to 96% in most individuals with acute respiratory failure needing ventilatory support to avoid the risks of unintentional hyperoxia or hypoxia.

👉Click on the link below to see the original study in the New England Journal of Medicine

Oxygen-Saturation Targets for Critically Ill Adults Receiving Mechanical Ventilation