PURPOSE: Hemothorax is defined as pleural fluid/serum hematocrit (HCT) ratio > 50%. The pleural fluid findings in acute hemothorax are clearly defined in the literature, but findings in chronic hemothorax are not as well established.
METHODS: We identified six cases of hemothorax by clinical history, radiographic imaging and pleural fluid analysis from a database of 1133 cases undergoing thoracentesis from 2001 to 2010 at the Medical University of South Carolina.
RESULTS: In four of the six cases, time from injury to diagnostic/therapeutic thoracentesis was within seven days (1, 4, 4, 5). The fluid was exudative with a pH range of 7.32 to 7.41. Lactate dehydrogenase (LDH) was elevated with a range of 210 to 884 and absolute neutrophil count (ANC) was elevated with a range of 1196 to 3631. In the remaining two cases, time from injury to thoracentesis was one week and 60 days. In these cases the pH range was 6.91 to 7.18, LDH range was 961 to 1679, and ANC range was 5943 to 8134. The microbiology and pathology were negative in all cases.
CONCLUSIONS: The development of inflammation and subsequent acidemia correlates to the duration of blood in the pleural space. In chronic hemothorax (greater than one week), the pleural fluid analysis resembles that of a sterile empyema showing a low pH, elevated LDH, and significantly elevated absolute neutrophil count.
CLINICAL IMPLICATIONS: Multiple mechanisms may explain the pleural fluid findings in chronic hemothorax: 1. impaired clearance of carbon dioxide and lactate due to development of a fibrinous membrane, 2. diminished erythrocyte Duffy Antigen Receptor for Chemokines (DARC) in old, lysed red blood cells leading to impaired chemokine scavenging allowing for uncontrolled neutrophil recruitment. Early drainage is essential to prevent the development of pleural fibrosis, and it’s end-stage complication of fibrothorax.
DISCLOSURE: The following authors have nothing to disclose: Matthew Divietro, John Huggins, Peter Doelken, Puncho Gurung, Steven Sahn
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