Prevalence, characteristics, drainage and outcome of radiologically diagnosed pleural effusions in critically ill patients

Objective: Pleural effusions in the intensive care unit (ICU) are clinically important. However, there is limited information regarding effusions in such patients. We aimed to estimate the prevalence, patient characteristics, mortality, effusion duration, radiological resolution, drainage, and reaccumulation rates of pleural effusions in ICU patients. Methods: This retrospective cohort study assessed all patients admitted to a tertiary hospital ICU from 1 January to 31 December 2015 with a chest x-ray report of pleural effusion. All chest x-ray reports were reviewed and data were combined with an established clinical ICU database. Statistical analysis of the combined dataset was performed. Results: Among 2094 patients admitted to the ICU, 566 (27%) had pleural effusions diagnosed by chest x-ray. The effusion median duration was 3 days (IQR, 1-5 days). Radiologically documented clearance of the effusion occurred in 243 patients (43%) and drainage was performed in 52 patients (9%). Among patients with effusion clearance, 80 (33%) reaccumulated the effusion. Drainage was more common in patients who experienced reaccumulation (19% v 7%; P = 0.004). Overall, 89 patients (16%) died, with 20% mortality among those with reaccumulation versus 9% among patients without reaccumulation (P = 0.037). Conclusion: Pleural effusions are common in ICU patients and drainage is infrequent. One-third of effusions reaccumulate, even after drainage, and one in six patients with an effusion die in hospital. This information helps clinicians estimate resolution rates, advantages and disadvantages of effusion drainage, and overall prognosis.