C23-21 Retrospective Analysis of Intrapleural Fibrinolytic Therapy and Intrapleural Hemorrhage Rates at Los Angeles General Medical Center

Rationale Intrapleural fibrinolytic therapy (IPFT) using tissue plasminogen activator and deoxyribonuclease administered via chest tubes has become a mainstay in managing pleural infections, malignant effusions, and retained hemothorax. The MIST-2 trial demonstrated that combination IPFT significantly reduced the need for surgical intervention and shortened the hospital length of stay. However, intrapleural hemorrhage has been described in case reports, though the true incidence remains uncertain. We sought to determine the historical rate of IPFT-associated intrapleural hemorrhage and identify risk factors for it at Los Angeles General Medical Center (LAGMC). Methods We performed a retrospective review of patients who received IPFT at LAGMC between December 2015 and March 2024, randomly selecting two-thirds of cases (276 total) for analysis. Poisson regression with robust standard errors modeled hemorrhage rates by age, number of fibrinolytic doses, serum urea nitrogen, creatinine, hemoglobin, platelet count, albumin, INR, RAPID score, and antiplatelet or anticoagulant use. Medication exposure was categorized as present, recent, or none. These associations were further examined by indication: pleural infection, malignant effusion, retained hemothorax, or multiple/other. Results The overall intrapleural hemorrhage rate was 5.4% (95% CI: 3.3%-8.9%). When stratified by treatment indication, rates were 2.2% for retained hemothorax, 5.6% for malignant effusion, 5.7% for multiple or other indications, and 6.3% for pleural infection. In the univariate Poisson regression models, older age (p = 0.019), elevated serum urea nitrogen (p = 0.019), creatinine (p = 0.015), and INR (p = 0.030) were all significantly associated with increased hemorrhage risk (Table 1). Hemoglobin, platelet count, albumin, RAPID score, and number of fibrinolytic doses were not significant. Aspirin use was significantly associated with increased rates of bleeding. Patients with present exposure to aspirin had a 4.84-fold higher hemorrhage rate (95% CI: 1.74-13.43; p = 0.003), and those with recent exposure had a 6.78-fold higher rate (95% CI: 1.10-41.60; p = 0.039), compared to those with no aspirin exposure. When stratified by fibrinolytic treatment indications, serum urea nitrogen and creatinine were positively associated with higher hemorrhage rates in pleural infections and inversely associated in retained hemothorax. Higher hemoglobin levels were associated with reduced intrapleural hemorrhage risk in pleural infection. Conclusions Intrapleural hemorrhage after IPFT occurred in 5.4% of cases at our institution. Older age, renal dysfunction, elevated INR, and aspirin exposure were associated with increased hemorrhage rates, identifying a modifiable risk factor for clinical practice. These findings highlight the importance of individualized risk assessment before IPFT.