Attenuation of lung reperfusion injury by modified ventilation and reperfusion techniques

Background: High ventilation and perfusion pressures after lung transplantation may have deleterious effects. We hypothesized that using combined protective approaches for ventilation and perfusion would be optimal for reducing injury and improving function after ischemia-reperfusion. Methods: Using an isolated, blood-perfused, rabbit lung model, lungs underwent 120 minutes of reperfusion either immediately (Sham) or after 18 hours of cold ischemia (IR). Groups Sham-P and IR-P underwent protective ventilation and reperfusion, and Groups Sham-C and IR-C underwent conventional ventilation and reperfusion. Protective ventilation involved gradually increasing the flow rate during 5 minutes to 1.8 fiters/min, and conventional ventilation entailed immediate initiation of flow at 1.8 liters/min. Protective reperfusion involved gradually increasing perfusion during 5 minutes to 60 ml/min, and conventional reperfusion entailed immediate perfusion at 60 ml/min. Two other groups underwent either protective ventilation with conventional perfusion or vice versa. Airway pressure, pulmonary artery pressure, and arterial blood gases were measured throughout reperfusion. Wet/dry weight, highest oxygenation index, and bronchoalveolar lavage (BAL) protein were also measured. Results: Protective ventilation and perfusion after ischemia (IR-P) resulted in significant improvements in lung function as measured by increased PO2 and decreased PCO2, airway pressure, and highest oxygenation index compared with conventional reperfusion (IR-C). Injury was significantly reduced in IR-P lungs as measured by reduced edema (wet/dry weight) and vascular leakage (BAL protein). In most cases, IR-P lungs performed better, with less injury than protective ventilation or perfusion alone. Conclusions: This protective approach of ventilation and perfusion after ischemia may improve lung function after transplantation, a simple method that could easily be applied clinically.