Pulmonary function after biventricular bypass for autologous lung oxygenation

Objective: Biventricular bypass (BVB) with autologous lung perfusion is an attractive concept to ameliorate systemic inflammatory response by eliminat ing the oxygenator from the extracorporeal circulation. The effect of biven tricular bypass as compared to heart-lung bypass (HLB) on pulmonary functio n parameters was therefore studied in an experimental model. Methods: Heart -lung bypass using a membrane oxygenator or biventricular bypass using the autologous lung for gas exchange was performed for 120 min in an alternatin g series of 12 mongrel dogs with the heart arrested for 90 min by crystallo id cardioplegia and 30 min reperfusion, followed by a 120 min observation p eriod. Systemic (CO, SVR) and pulmonary hemodynamics (PVR), extravascular l ung water (EVLW, double indicator), gas exchange (FiO(2), PaO2, PaCO2), lun g compliance (PC), and ventilation (RMV) at FiO(2) = 0.5 required to mainta in PaCO2 at 40 mmHg, were measured. Blood cell counts (Leuco, Thrombo) were performed. Results: All animals were weaned from extracorporeal circulatio n without inotropes, no differences were observed in cardiac output and blo od pressures. The following data were obtained in % change from pre-bypass values 60 min after extracorporeal circulation (*:P < 0.05, HLB vs. BVB): P VR, + 108 vs. +45*; EVLW, +21 vs. -2*; PC, -12 vs. +4*; PaO2, -8 vs. +21; R MV, +21 vs. +2*; Leuco, -65 vs. - 12*; Thrombo, -62 vs. -35*. Conclusion: D uring and after heart-lung bypass the lung is subject to severe ischemia-re perfusion injury as indicated by edema, cell trapping, and impaired gas exc hange. The data demonstrate superior preservation of pulmonary mechanics an d function after biventricular bypass as compared to heart-lung bypass and support the clinical strategy of using biventricular bypass in patients wit h impaired lung function. (C) 2000 Elsevier Science B.V. All rights reserve d.