Abstract
Abnormal oxygenation may influence thrombosis, but evidence in catheterized critically ill patients remains limited. We examined whether the first arterial partial pressure of oxygen (PaO
2
) measured within 24 hours after qualifying invasive venous catheter insertion was associated with documented acute upper-body deep or central venous thrombosis during hospitalization. This retrospective observational cohort study used the Medical Information Mart for Intensive Care IV database, version 2.2 (MIMIC-IV v2.2) (2008–2019). Adult intensive care unit admissions were included when a qualifying invasive venous catheter was present and an arterial PaO
2
measurement was obtained after insertion, within 24 hours, and while the catheter remained in situ. PaO
2
was analyzed continuously and categorically (≤80, 81–100, and >100 mmHg). Logistic regression models sequentially adjusted for patient characteristics, laboratory measurements, catheter characteristics, measurement timing, inspired oxygen concentration, respiratory support, and non-respiratory organ dysfunction. Multiple imputation addressed missing covariate data, and patient-clustered robust standard errors accounted for repeated admissions. The cohort included 11,277 hospital admissions from 10,789 patients; 195 admissions (1.73%) had the primary outcome. In the unadjusted model, higher PaO
2
was associated with lower odds of the outcome (odds ratio [OR] per 10-mmHg increase, 0.970; 95% confidence interval [CI], 0.952–0.987), but this association attenuated after adjustment. In the fully adjusted model, PaO
2
was not associated with the outcome (OR, 1.008; 95% CI, 0.989–1.027; P = 0.430). Most secondary analyses supported the primary result, although the 60-minute sensitivity analysis yielded adjustment-dependent estimates. In the complete cohort, a single early post-insertion PaO
2
measurement was not independently associated with documented acute upper-body deep or central venous thrombosis. These findings do not support PaO
2
-based thrombosis risk stratification or modification of oxygen therapy for thrombosis prevention. Future studies should incorporate repeated oxygenation measurements and accurately timed, imaging-confirmed thrombotic outcomes.