The association of arterial partial oxygen pressure with mortality in critically ill sepsis patients: a nationwide observational cohort study

Abstract

Background: Although several trials were conducted to optimize the oxygenation range in intensive care unit (ICU) patients, no studies have yet reached a universal recommendation on the optimal a partial pressure of oxygen in arterial blood (PaO₂) range in patients with sepsis. Our aim was to evaluate whether a relatively high arterial oxygen tension is associated with longer survival in sepsis patients compared with conservative arterial oxygen tension.

Methods: From the Korean Sepsis Alliance nationwide registry, patients treated with liberal PaO₂ (PaO₂ ≥ 80 mm Hg) were 1:1 matched with those treated with conservative PaO₂ (PaO₂ < 80 mm Hg) over the first three days after ICU admission according to the propensity score. The primary outcome was 28-day mortality.

Results: The median values of PaO₂ over the first three ICU days in 1211 liberal and 1211 conservative PaO₂ groups were, respectively, 107.2 (92.0-134.0) and 84.4 (71.2-112.0) in day 1110.0 (93.4-132.0) and 80.0 (71.0-100.0) in day 2, and 106.0 (91.9-127.4) and 78.0 (69.0-94.5) in day 3 (all p-values < 0.001). The liberal PaO₂ group showed a lower likelihood of death at day 28 (14.9%; hazard ratio [HR], 0.79; 95% confidence interval [CI] 0.65-0.96; p-value = 0.017). ICU (HR, 0.80; 95% CI 0.67-0.96; p-value = 0.019) and hospital mortalities (HR, 0.84; 95% CI 0.73-0.97; p-value = 0.020) were lower in the liberal PaO₂ group. On ICU days 2 (p-value = 0.007) and 3 (p-value < 0.001), but not ICU day 1, hyperoxia was associated with better prognosis compared with conservative oxygenation., with the lowest 28-day mortality, especially at PaO₂ of around 100 mm Hg.

Conclusions: In critically ill patients with sepsis, higher PaO₂ (≥ 80 mm Hg) during the first three ICU days was associated with a lower 28-day mortality compared with conservative PaO₂.

Keywords: Hyperoxia; Hypoxia; Intensive care medicine; Oxygen; Sepsis.

Fig. 1

Flow chart of analysis population. PaO₂, Partial Pressure of Oxygen in Arterial Blood

Fig. 2

Kaplan-Meier estimates of cumulative probabilities of 28-day survival in propensity-score matched cohort. PaO₂, Partial pressure of oxygen in arterial blood; HR Hazard ratio; CI Confidence interval

Fig. 3

The results of prespecified subgroup analyses of 28-day mortality. PaO₂, Partial pressure of oxygen in arterial blood; HR, Hazard ratio; CI, Confidence interval; ARDS, Acute respiratory distress syndrome

Fig. 4

Dose Response Association of PaO₂ value per ICU day with 28-day mortality. Restricted Cubic Spline Models of Hazard Ratios of PaO₂ value per ICU day and 28-day Mortality. (A) ICU day 1, (B) ICU day 2, (C) ICU day 3. Knots set at the 5th, 35th, 65th, and 95th percentiles of PaO₂. Reference is the 5th percentile. Solid lines, hazard ratios; shadow, 95% confidence interval. Model adjusted for age, sex, comorbidities (Lung, Neurology, Liver, Kidney, and Hematology malignancy), infection site, initial sequential organ failure assessment score, lactate level, treatments (steroid and source control), organ support at ICU Day 1 (mechanical ventilation, continuous renal replacement therapy, and vasopressor)