Risk factors for spontaneous bacterial empyema in cirrhotic patients with hydrothorax

Spontaneous bacterial empyema (SBEM) is a rare complication of portal hypertension. The characteristics and risk factors for SBEM are not well known. This study was performed to investigate the risk factors for SBEM in cirrhotic patients with hydrothorax.

From July 1996 to December 1998, 862 cirrhotic patients were studied. All patients underwent chest radiography, abdominal sonography or computed tomography after admission to detect the existence of pleural effusion. Pleural fluid was obtained after thoracentesis and sent for analysis. The clinical and laboratory data from patients with sterile hydrothorax and from SBEM at the time of first episode were compared.

Seventeen patients had 26 episodes of SBEM during the study period, 56% (14 of 26) of these SBEM episodes were associated with spontaneous bacterial peritonitis (SBP) and 31% (8 of 26) were associated with bacteremia. The incidence of SBEM was 2% (17 of 862) in cirrhotic patients and 13% (17 of 132) in cirrhotics with hydrothorax. Patients with SBEM had a higher Child-Pugh score, lower serum albumin, prolonged prothrombin time, lower pleural fluid protein, and higher rate of associated SBP than patients with sterile hydrothorax. Multivariate analysis revealed that pleural fluid protein level (p = 0.0035) and presence of SBP (p = 0.0062) were predictive factors of SBEM. The hospitalization mortality rate of SBEM was 38%.

Patients with advanced liver disease, low pleural fluid protein level, or SBP are predisposed to SBEM. A diagnostic thoracentesis should be performed in cirrhotic patients with pleural effusion when infection is suspected or clinical deterioration occurs.