Risk factors of prolonged postoperative pleural effusion after repair of tetralogy of Fallot.

Background: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, and total correction is the definitive treatment. Chest tube drainage of pleural effusion (PE) is essential after surgery. Prolonged PE (> 7 days) is one of the complications; it may increase hospital stay and the risks of morbidity and mortality. The aim of this study was to investigate and analyze the possible risk factors for prolonged PE after total correction of TOF.
Methods: Thirty-seven patients who received total correction of TOF between July 1999 and April 2001 were included in this study. They were divided into 2 groups according to the duration of chest tube drainage for postoperative PE: Group I had postoperative PE < or = 7 days; Group II had postoperative PE > 7 days. Detailed records were taken on patients' demographic characteristics, blood parameters, surgery, electrocardiographic and radiologic data, and angiographic and echocardiographic findings. The data of the 2 groups were compared using the Wilcoxon rank-sum test and Fisher's exact test. Risk factors were analyzed by logistic regression and model selection.
Results: Of the 37 patients, 16 were male and 21 were female. There were 32 patients (86.5%) in Group I and 5 (13.5%) in Group II. Mean patient age at repair was 1.82 +/- 1.29 years (range, 0.53-3.11 years). Significant differences (p < 0.05) between the 2 groups were noted for gender, age at repair, body weight, presence of wound infection, duration on heart-lung machine (bypass time), oxygen saturation before surgery, duration of endotracheal intubation, length of hospital stay, and Nakata index. These risk factors were analyzed by logistic regression and model selection. Two models were set up: Model 1--oxygen saturation before surgery, presence of wound infection, age at repair; Model 2--oxygen saturation before surgery, presence of wound infection.
Conclusion: Prolonged PE is a significant morbidity after TOF repair. The risk factors for prolonged PE are gender, age at repair, body weight, bypass time, low oxygen saturation before surgery, wound infection after surgery, duration of endotracheal intubation, length of hospital stay, and Nakata index. Oxygen saturation before surgery and wound infection were major risk factors while age at repair was a confounder.