Study objectives: To assess the impact of routine
thoracentesis on diagnostic assessment and therapeutic measures in
patients with clinically documented pleural effusions.
Design and setting: Prospective, 1-year, three-center study
in medical ICU (MICU) patients with physical and radiographic evidence
of pleural effusion.
Patients: Of 1,351 patients
admitted to three MICUs during the study period, 113 patients had
physical and radiographic evidence of pleural effusion, yielding an
annual incidence of 8.4%.
thoracentesis in 82 patients without contraindications to
Measurements and results: Twenty
patients (24.4%) had a transudate, 35 patients (42.7%) had an
infectious exudate (parapneumonic, n = 21; empyema, n = 14), and 27
patients (32.9%) had a noninfectious exudate. Laboratory
parameters including the leukocyte count, the neutrophil percentage in
pleural fluid, and the fluid/serum protein and lactate dehydrogenase
ratios differed significantly among the three groups. Thoracentesis
yielded improvements in the diagnosis and/or treatment in 46 patients
(56%): the presumptive (prethoracentesis) diagnosis was changed in 37
patients (32 patients with certain benefit and 5 patients with probable
benefit from thoracentesis), of whom 27 patients received a change in
treatment based on the new diagnosis; 9 other patients received a
change in treatment although the diagnosis remained the same. The only
complications were pneumothorax in six patients (7%), all with a
favorable outcome after drainage.
Infection was the main cause of pleural effusions detected based on
physical and radiographic findings in our MICU population. Routine
thoracentesis proved a simple and safe means of improving the diagnosis