Obstructive Sleep Apnea in Critically Ill Patients: A Structured Narrative Review of Prevalence, Diagnostic Barriers, and Clinical Implications in the ICU.

Obstructive sleep apnea (OSA) is a highly prevalent yet frequently underdiagnosed condition that is associated with significant cardiopulmonary, metabolic, and neurocognitive outcomes. Risk factors for OSA overlap with illnesses commonly observed in intensive care unit (ICU) patients, resulting in a disproportionately elevated burden on healthcare. This structured narrative review synthesizes current evidence regarding the prevalence, diagnostic challenges, and clinical implications of obstructive sleep apnea (OSA) in critically ill adults admitted to intensive care units (ICUs) using PubMed, EMBASE, and Scopus. Key search terms included "obstructive sleep apnea," "ICU," and "critical illness." Results showed that OSA is present in up to 60-70% of ICU patients, yet only ~5% are formally diagnosed during hospitalization. Underdiagnosis is linked to prolonged mechanical ventilation, extubation failure rates as high as 30%, 2-fold higher perioperative complication rates, cardiovascular instability, 1.8-fold greater 30-day ICU readmission rates, and 2.2-fold mortality. Standard screening tools have limited applicability in ICU patients. Emerging alternatives, such as overnight oximetry, polygraphy, and machine learning models lack validation. Our analyses reveal that current diagnostic and treatment strategies are poorly adapted to critically ill patients. Integration of OSA as a part of ICU management, diagnosis, and intervention may reduce readmissions and mortality.