A novel paracorporeal method for isolated rodent lung reperfusion

Background The isolated perfused lung model is commonly used in small anima ls to study lung function after preservation and cold storage. Measurements of oxygenation, compliance, and capillary filtration coefficient (K-f) per mit analysis of preservation solutions or modifications of these solutions. However, inter-investigator variability using different Perfusates makes c omparisons difficult. Whole blood perfusion more closely mimics the in vivo situation, but extracorporeal circulation may alter the physiologic integr ity of the model. Paracorporesal support has been used, but this technique required mechanical ventilation of the support rodent sand did not incorpor ate a method for determining K-f We evaluated a less-invasive technique, of providing cross-circulatory syngeneic support, maintaining the ability to compute K-f Methods. Angiocatheters were inserted into both femoral arteries and one fe moral. vein of the support rat. The venous cannula was connected to the pul monary artery of the ex vivo lung block to provide inflow, pulmonary efflue nt blood from the lung block was collected via a left atrial cannula and re turned to the support rat via the femoral artery. A separate, height-adjust able column was included in the circuit for measurement of K-f Results. Each support rat was used to sequentially perfuse three double-lun g blocks. The inflow sample to each lung block was analyzed for pH, pO(2), pCO(2), and hematocrit to follow alterations in support rat physiology, The re were no statistical differences in the pH, pO(2), or hematocrit, No sign ificant differences were noted in the pO(2) of the pulmonary effluent blood or the K-f analyzed to determine whether the sequence of reperfusion affec ted the pulmonary function assessment, Conclusions. The syngeneic support rat delivers constant pressure systemic venous blood at stable physiologic parameters to the ex vivo lung block, Re circulation of the perfusate through the support rat diminishes the need to pool blood from donors, detoxifies and deoxygenates pulmonary effluent blo od, and permits examination of sequential lung blocks. This technique repre sents a hybrid model between isolated perfused and orthotopic transplant mo dels, maintaining K-f determination, a sensitive indicator of reperfusion i njury. This technique could be applicable to reperfusion injury models of o ther organs (using arterial inflow instead) and may permit increased standa rdization among investigators.