A physiological comparison of flutter valve drainage bags and underwater seal systems for postoperative air leaks

摘要

BACKGROUND—A study wasundertaken to compare the relative physiological effects of underwaterseal (UWS) versus flutter valve (FV) pleural drainage systems in thetreatment of postoperative air leaks.
METHOD—Fourteenpatients with air leaks of 1-11 days duration, following lobectomy (n = 5), bullectomy (n = 4), decortication (n= 4), and pleural biopsy (n = 1) were analysed. Intrapleural pressure (IPP) measurements were madeusing an in-line external strain gauge connected directly to theintercostal tube. Patients were connected simultaneously to both UWSand FV drainage systems and pressures were measured sequentially,isolating each system in turn. Maximum (IPPmax) and minimum (IPPmin)intrapleural pressures were calculated from graphic traces. The degreeof lung expansion was recorded by chest radiography.
RESULTS—At restingtidal volume IPPmax was significantly higher with the UWS system (meandifference 0.8 mm Hg, 95% CI 0 to 1.6, p= 0.046) and IPPmin wassignificantly lower with the FV system (1.8 mm Hg, 95% CI 0.3 to 3.3, p = 0.023). The lung was fully expanded in 50% of patients at the timeof study. The mean difference in IPPmin between systems wassignificantly increased when the lung was fully expanded (mean 2.8 mmHg, 95% CI 0.1 to 5.5, p= 0.042). The mean difference in IPPmax wasnot affected by the degree of lung expansion (0.79, 95% CI -0.83 to2.4, p = 0.31).
CONCLUSION—The resultsof this study suggest that, when postoperative air leak exists withouta persistent pleural space, the flutter valve may provide aphysiologically more effective alternative to the underwater sealdrainage system.