Objective To investigate the effects of
desflurane inhalation on pulmonary alveolar-capillary membrane
permeability and the
inflammatory cell counts in broncho-alveolar lavage fluid (BALF) during endotoxin-induced acute lung injury in rats. Methods Forty-eight Wistar rats weighing 200-290 g were anesthetized with intraperitoneal pentobarbital 100mg·kg-1 , tracheotomized and mechanically ventilated. PETCO2 was maintained at 35-45 mm Hg (VT 8 ml·kg-1 , RR 65-70 bpm). Right carotid artery and left femoral vein were cannulated for BP monitoring and fluid and drug administration. The animals were randomly divided into four group with 12 animals in each group : (1) control group received normal saline (NS) 1.2 ml i.v. followed by 4 h mechanical ventilation; (2) LPS group received LPS (055:B5, Sigma) 5 mg·kg-1 followed by 4h mechanical ventilation; (3)
Desflurane group A and B received LPS 5 mg· kg-1 followed by desflurane inhalation for 4 h at 1 MAC (desflurane group A) or 1.5 MAC (desflurane group B) . Six animals in each group received Evans blue 50 mg·kg-1 at the beginning of the experiment for determination of pulmonary alveolar-capillary membrane
permeability at the end of the experiment. The animals were sacrificed by exsanguinations at the end of 4h mechanical ventilation. Blood was collected for determination of total plasma protein concentration. Lungs were removed. The right lung was lavaged and BALF was collected for determination of protein content, and differential inflammatory cell counts. The left lung was used for microscopic examination. The morphologic changes were scored 0-3 (0 = normal, 3 = severe morphologic changes). In addition wet/dry lung weight ratio, pulmonary permeability index (BALF protein concentration /total plasma protein concentration×10-3 ) and mortality rate were also determined. Results In group 3 (desflurane 1 MAC) W/D lung weight ratio and lung water content significantly increased compared with those in LPS group. In group 4 ( desflurane 1.5 MAC) W/D lung weight ratio, lung water content, pulmonary permeability index, Evans blue content in lung tissue, morphological change scores and mortality rate were all significantly increased compared with LPS group (group 2). There was no significant difference in total and differential inflammatory cell counts in BALF between group 2 and 4.Conclusion Desflurane inhalation is detrimental to the lungs acutely injured by endotoxin in a dose-dependent manner.