CONSEQUENCES OF VASCULAR FLOW ON LUNG INJURY-INDUCED BY MECHANICAL VENTILATION

To investigate whether the magnitude of blood flow contributes to vent ilator-induced lung injury, 14 sets of isolated rabbit lungs were rand omized for perfusion at either 300 (Group A: n = 7) or 900 ml/min (Gro up B: n = 7) while ventilated with 30 cm H2O peak static pressure. Con trol lungs (Group C: n = 7) were ventilated with lower peak static pre ssure (15 cm H2O) and perfused at 500 ml/min. Weight gain, changes in the ultrafiltration coefficient (Delta K-f) and lung static compliance (CL), and extent of hemorrhage (scored by histology) were compared. G roup B had a larger decrease in CL (-13 +/- 11%) than Groups A (2 +/-. 6%) and C (5 +/- 5%) (p < 0.05). Group B had more hemorrhage and gain ed more weight (16.2 +/-: 9.5 g) than Groups A (8.7 +/- 3.4 g) and C ( 1.6 +/- 1.0 g) (p < 0.05 for each pairwise comparison between groups). Finally, K-f (g.min(-1.)cm H(2)O(-1.)100 g(-1)) increased the most in Group B (Delta K-f = 0.26 +/- 0.20 versus 0.17 +/- 0.10 in Group A an d 0.05 +/- 0.04 in Group C; p < 0.05 for B versus C). We conclude that the intensity of lung perfusion contributes to ventilator-induced lun g injury in this model.