Pulmonary vascular compliance and pleural effusion duration after the Fontan procedure

Preoperative risk analysis for Fontan candidates is still less than optimal in that patients with apparently low risks may have a poor outcome, such as prolonged pleural drainage, protein-losing enteropathy, pulmonary thromboembolism and death. We hypothesized that low pulmonary vascular compliance (PVC) is a risk factor for persistent pleural effusion after the Fontan operation.

A retrospective review of 85 patients who underwent the extracardiac Fontan procedures (median age: 3.87 years) was performed. Fontan risk score (FRS) was calculated from 12 categorized preoperative anatomical and physiological variables. PVC (mm(2)/m(2) x mmHg) was defined as pulmonary artery index (mm(2)/m(2)) divided by total pulmonary resistance (Wood Unit x m(2)) and pulmonary blood flow (L/min/m(2)), based on the electrical circuit analogy of the pulmonary circulation. Chest tube indwelling time was log-transformed (log indwelling time, LIT) to fit normal distribution, and the relationship between perioperative predictors and LIT was analyzed by multiple linear regression.

Preoperative PVC, chest tube indwelling time and LIT ranged from 6 to 94.8 mm(2)/mmHg/m(2) (median: 24.8), 3 to 268 days (median: 20 days), and 1.1 to 5.6 (mean: 2.9, standard deviation: 0.8), respectively. FRS, PVC, cardiopulmonary bypass time (CPB) and central venous pressure at postoperative 12 h were correlated with LIT by univariable analyses. By multiple linear regression, PVC (p=0.002) and CPB (p=0.003) independently predicted LIT, explaining 22% of the variation. The regression equation was LIT=2.744-0.016 PVC+0.007 CPB.

Low pulmonary vascular compliance is an important risk factor for prolonged pleural effusion drainage after the extracardiac Fontan procedure.