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.