Rapid improvement in abnormal pulmonary epithelial permeability after stopping cigarettes

A new, non-invasive method of measuring pulmonary epithelial damage in man was compared with traditional tests of small-airway function. Pulmonary epithelial permeability was expressed as the half-time clearance from the lung into blood of (99m)Tc-diethylene triaminepenta-acetic acid ((99m)Tc-DTPA) deposited predominantly in the alveoli from an inhaled aerosol.Recovery from abnormal pulmonary permeability was recorded after stopping smoking for 21 days in a group of young symptomless cigarette smokers. Before stopping smoking there was a significant correlation between half-time lung clearance of (99m)Tc-DTPA and carboxyhaemoglobin concentration (r=0.69; p <0.05). There was no correlation between carboxyhaemoglobin value and closing volume, the only other abnormal test of airway function. Twenty-four hours after stopping smoking the mean half-time lung clearance of (99m)Tc-DTPA had increased significantly (p <0.001) from a baseline of 15.8 min (SEM 1.3 min) to 25.5 min (SEM 2.5 min). The mean half-time clearance continued to increase to a maximum of 35.5 min (SEM 3.1 min) at seven days, but was significantly less than the reported half-time clearance for non-smokers (59 min, SEM