Optimal PaO 2 is 130-160 mmHg in the first week for sepsis patients in ICU: a retrospective cohort study based on MIMIC-IV database

Abstract Background The relationship between the partial pressure of oxygen in arterial blood (PaO 2 ) and the prognosis of sepsis patients, and its potential variation over time, remains unclear. The optimal PaO 2 range for sepsis patients has always been a contentious issue, with no consensus. We aimed to explore the association between different levels of PaO 2 exposure over time and the 28-day mortality of sepsis patients, and to identify the optimal PaO 2 range for sepsis patients within a specific time frame. Methods We retrieved data on adult patients diagnosed with sepsis within 24 hours before or after ICU admission from the Medical Information Mart for Intensive Care IV (MIMIC-IV; version 2.2) database. We excluded patients who were not admitted to the ICU for the first time, those with ICU stay <24 hours, and those without PaO 2 results during their ICU stay. We calculated the time-weighted average (TWA) of PaO 2 and used piece-wise exponential additive mixed models (PAMMs) to estimate the time-dependent changes in the association between TWA-PaO 2 and patient prognosis. Results A total of 16,880 sepsis patients were included in the MIMIC cohort. Results indicated that patients' TWA-PaO 2 correlates with increased 28-day mortality after intensive care unit (ICU) admission in sepsis patients, and this association was mainly manifested in the early course of the disease. With a time window of the first 1-7 days after ICU admission, the optimal TWA-PaO 2 range for sepsis patients was ≥130 mmHg and ≤ 160 mmHg. Increased exposure time, proportion of exposure time, and exposure dose of high-risk PaO 2 outside the range were all associated with an increased risk of 28-day mortality. Conclusion PaO 2 in sepsis patients should be closely monitored. During the first 1-7 days of ICU admission, PaO 2 should be maintained within the range of ≥130 mmHg and ≤ 160 mmHg. A dose-dependent relationship exists between high-risk PaO 2 outside the range and patient outcome.