HIGH AIRWAY PRESSURE INDUCED LUNG INJURY IS NOT PREVENTED BY PERFLUOROCARBON ASSOCIATED GAS EXCHANGE (PAGE). 2037

Abstract

Healthy lungs subjected to mechanical ventilation with high airway pressure-high tidal volume develop high permeability edema. We investigated whether the same type of ventilation on perfluorocarbon filled lungs would result in similar damage. Adult rats (350- 500 gm) (BW) were randomized to intermittent positive pressure ventilation with low inspiratory pressure (PIP)- tidal volume (VT) (IPPV) or high pressure - high tidal volume(HIPPV). Within each group, half were randomized to have their lungs initially filled with perfluorocarbon (PF)(APF-140, Air Products and Chemicals. Allentown PA) to functional residual capacity (1ml/100gm BW). Rates were 60 and 25 breaths/ min for the low VT and high VT groups. Arterial blood gases, lung compliance(Cdyn) and pulmonary airway resistance (Raw) were serially measured. After 30 min, the animals were sacrificed and wet and dry lung weights measured to assess extravascular lung water (Qwl) (corrected for lung hemoglobin and fluorocarbon content). Microvascular permeability was assessed by the 30-min 125I-albumin uptake by the lungs and measured as lung (extravascular) albumin space (Alb.Sp). PF normo-ventilation required higher PIP for normocapnea because of significantly higher Raw but did not result in more lung injury. There was no protective effect of PF at high volume ventilation. Table