Aerodynamic evaluation of crystalloid and colloid flush perfusion for lung preservation

Abstract

To assess the effectiveness of pulmonary perfusion we evaluated the lung mechanics of 36 canine lungs in an isolated perfused working lung (IPWL) model. Four groups of lungs ( n = 9 each) were preserved by pulmonary artery flushing with either high-potassium colloid (UW), high-potassium crystalloid (EuroCollins', EC), low-potassium crystalloid control (lactate), or low-potassium substrate-enhanced crystalloid (RPMI) followed by 130 ± 10 min of cold storage. Ventilation remained constant (TV 10 ml/kg at 14 breaths/min with 5 cm H 2O PEEP). Assessed data included lung resistance ( R), timed expiratory volume (EV 0.3 sec as %TV), lung compliance ( C), elastic work ( W el), and flow-resistive work ( W res). Immediately following storage, R and W el were similar for all groups (16 ± 3 cm H 2O/liter/sec and 149 ± 18 gm/min). UW preserved lungs were less compliant (1.5 ± 0.1 × 10 −2 liter/cm H 2O) and required more inspiratory work ( W res 5.8 ± 0.8 gm/min) compared to the low-potassium crystalloid (Lactate) group (2.0 ± 0.1 × 10 −2 liter/cm H 2O and 3.4 ± 0.6 gm/min, respectively, P < 0.05). For 3 hr of reperfusion, crystalloid lungs showed no significant change in R, C, W el, or W res. In contrast, R of the UW group increased significantly to 32 ± 5 and 40 ± 8 cmH 2O/liter/sec at 1 and 3 hr, respectively. By 90 min, the latter lungs became less compliant (1.0 ± 0.1 × 10 −2 liter/cm H 2O) and required more work to accommodate the same TV ( W el 170 ± 8 vs 144 ± 8 gm/min at start) and to overcome expiratory flow resistance ( W res 9.8 ± 1.5 vs 5.8 ± 0.8 gm/min at start). From these data, it may be concluded that colloid-preserved lungs are stiffer, less compliant, and require greater amount of work, for the same TV to expand or to overcome flow possibly due to inadequate peribronchial preservation. Aerodynamic variables are easily measured, sensitive indicators of lung damage in the IPWL model.