It remains unclear whether conservative oxygen therapy (COT) or liberal oxygen therapy (LOT) is more beneficial to the clinical outcomes of intensive care unit (ICU) patients. We systematically reviewed the efficacy and safety of conservative versus liberal oxygen therapy for ICU patients.

We systematically searched PubMed, Embase, Web of Science, Scopus, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, MedRxiv, and BioRxiv for reports on randomized controlled trials (RCTs) that compared the effects of COT versus LOT on the clinical outcomes of ICU patients published in English before April 2024. The primary outcome was the mortality rate, secondary outcomes included ICU and hospital length of stay, days free from mechanical ventilation support (MVF), vasopressor-free time (VFT), and adverse events.

In all, 13 RCTs involving 10,632 patients were included in analyses. Meta-analysis showed COT did not reduce mortality at 30-day (risk ratio [RR] = 1.01, 95% confidence interval [CI] 0.94 to 1.09, I ²  = 42%, P = 0.78), 90-day (RR = 1.01, 95% CI 0.95 to 1.08, I ²  = 9%, P = 0.69), or longest follow-up (RR = 1.00, 95% CI 0.95 to 1.06, I ²  = 22%, P = 0.95) compared to LOT in ICU patients. In subgroup analyses, no significant difference was observed between the two groups in terms of the different ICU, baseline P/F, and actual PaO ₂ . In addition, COT did not affect ICU length of stay, hospital length of stay, or VFT, it only affected MVF days.

COT did not reduce all-cause mortality in ICU patients. Further RCTs are urgently needed to confirm the impact of COT strategy on specific populations.