Detecting Alveolar Epithelial Injury following Volatile Anesthetics by 99mTc DTPA Radioaerosol Inhalation Lung Scan

Abstract

Background: Many volatile anesthetics have long been thought to affect alveolar epithelial permeability. Objective: The purpose of this study was to examine the acute effects of volatile anesthetics on the permeability of the alveolocapillary barrier to ^99mTc DTPA. Methods: Twenty-seven patients (24 females, 3 males, age 29–73 years) undergoing operation were enrolled in this study and grouped according to the type of anesthesia received. Group 1 patients were administered 1% halothane. Group 2 patients were given 1.5% isoflurane. Intravenous anesthesia without volatile anesthetics were used for group 3 patients. Before and after anesthesia, ^99mTc DTPA radioaerosol inhalation lung scans were performed to detect alveolar epithelial injury due to volatile anesthetics. The negative slope of the regression line was designated as the ^99mTc DTPA pulmonary clearance rate and was expressed in terms of percentage decrease in radioactivity per minute. Results: In group 1, the ^99mTc DTPA clearance rates were 1.26 ± 0.34 and 1.29 ± 0.38 before and after anesthesia, respectively. The difference was not significant (p > 0.05). In group 2, the rates were 0.76 ± 0.20 and 1.10 ± 0.37, before and after anesthesia, respectively. The difference was significant (p < 0.05). In group 3, the clearance rates were 1.07 ± 0.38 and 1.21 ± 0.48, before and after anesthesia, respectively. The difference was not significant. Conclusions: Following isoflurane administration, the more rapid pulmonary clearance of ^99mTc DTPA indicates that isoflurane increases the permeability of the alveolo-capillary barrier.