DESATURATION EVENTS, THEIR PREDICTORS, AND ASSOCIATION WITH ADVERSE OUTCOMES IN HOSPITALIZED MEDICAL PATIENTS

Background: Intermittent desaturation events (SpO₂ <90%) are common in hospitalized medical patients and may occur even in patients with normal admission oxygen saturation. Each desaturation event may cause or exacerbate tissue hypoxia, myocardial ischemia, arrhythmias, and neurological dysfunction. However, the frequency, predictors, and clinical significance of desaturation events in hospitalized medical patients at Royal Medical Services have not been well characterized.
Objective: To evaluate the frequency, predictors, and clinical significance of desaturation events (SpO₂ <90%) in hospitalized medical patients.
Methods: A retrospective observational cohort study was conducted at King Hussein Medical Center, Jordan. Adult patients (≥18 years) admitted to internal medicine departments between February 2021 and November 2025, with serial SpO₂ monitoring, were included. Data extracted included demographics, admission diagnosis, AACCI, CFS, GFRS, admission SpO₂, all documented SpO₂ values, number of desaturation events (SpO₂ <90%), deep desaturation events (SpO₂ <85%), inflammatory markers (SII, NLR), nutritional status (albumin, GNRI), fluid balance (HHR), length of stay, ICU transfer, mechanical ventilation, and in-hospital mortality. Poisson regression assessed the association between number of desaturation events and outcomes.
Results: Among 847 patients (mean age 68.4±14.2 years, 54.6% male), at least one desaturation event occurred in 42.4% (n=359). Deep desaturation (SpO₂ <85%) occurred in 18.7% (n=158). Independent predictors included: admission SpO₂ <92% (OR=3.45), pneumonia (OR=2.84), COPD (OR=2.56), heart failure (OR=2.12), CFS ≥5 (OR=1.98), elevated SII (OR=1.85), hypoalbuminemia (OR=1.78), and fluid overload (OR=1.68). Patients with desaturation had longer stays (median 14 vs. 8 days, p<0.001), higher ICU transfer (28.4% vs. 6.8%), higher ventilation (18.4% vs. 3.5%), and higher mortality (14.5% vs. 3.5%). Each additional desaturation event was associated with a 12% increase in mortality risk (aRR=1.12, 95% CI: 1.06–1.18).
Conclusion: Desaturation events (SpO₂ <90%) are common in hospitalized medical patients, affecting 42.4%, and are independently associated with adverse outcomes in a dose-response manner. Admission SpO₂ <92%, pneumonia, COPD, heart failure, frailty, elevated SII, hypoalbuminemia, and fluid overload are independent predictors.