PLEURAL EFFUSIONS IN THE MEDICAL ICU - PREVALENCE, CAUSES, AND CLINICAL IMPLICATIONS

Objective: To determine tile prevalence and causes of pleural effusion s in patients admitted to a medical ICU (MICU). Design: Prospective. S etting: MICU in a tertiary care hospital. Patients: One hundred consec utive patients admitted to the MICU at the Medical University of South Carolina whose length of stay exceeded 24 h had chest radiographs rev iewed daily and chest sonograms pet-formed within 10 h of their latest chest radiograph. Results: The prevalence of pleural effusions in 100 consecutive MICU patients was 62%, with 41% of effusions detected at admission. Fifty-seven of 62 (92%) pleural effusions were small. Cause s of pleural effusions were as follows: heart failure, 22 of 62 (35%); atelectasis, 14 of 62 (23%); uncomplicated parapneumonic effusions, s even of 62 (11%); hepatic hydrothorax, five of 62 (8%); hypoalbuminemi a, five of 62 (8%); malignancy, two of 62 (3%); and unknown, three of 62 (5%). Pancreatitis, extravascular catheter migration, uremic pleuri sy, and empyema caused an effusion in one instance each. Heart failure was the most frequent cause of bilateral effusions (13/34 [38%]). Whe n compared with patients who never had effusions during their MICU sta y, patients with pleural effusions were older (54+/-2 years, mean+/-SE M, vs 47+/-2 years [p=0.04]), had lower serum albumin concentration (2 .4+/-0.1 vs 3.0+/-0.01 g/dL [p=0.002]), higher acute physiology and ch ronic health evaluation II scores during the initial 24 h of MICU stay (17.2+/-1.1 vs 12+/-1.2 [p=0.010]), longer MICU stays (9.8+/-1.0 vs 4 .6+/-0.7 days [p=0.0002]), and longer mechanical ventilation (7.0+/-1. 3 vs 1.9+/-0.7 days [p=0.004]). No patient died as a direct result of his or her pleural effusion. Chest radiograph readings had good correl ation with chest sonograms (p<0.0001). Conclusion: Pleural effusions i n MICU patients are common, and most are detected by careful review of chest radiographs taken with the patient in erect or semierect positi on. When clinical suspicion for infection is low, observation of these effusions is warranted initially, because most are caused by noninfec tious processes that should improve with treatment of the underlying d isease.