Sidestream smoke inhalation decreases respiratory clearance of 99mTc-DTPA acutely.
BACKGROUND
The permeability of the alveolar-capillary barrier to an inhaled aerosol of technetium 99m labelled diethylenetriamine penta-acetate (99mTc-DTPA) is used as an index of alveolar epithelial injury. Permeability is greatly increased in active smokers.


OBJECTIVE
To determine the effect of sidestream smoke inhalation on permeability as this has not been described previously.


METHODS
We measured lung clearance of inhaled 99mTc-DTPA aerosol in 20 normal non-smoking subjects before and after exposure to one hour's sidestream smoke inhalation.


RESULTS
Measured carbon monoxide (CO) levels rose to maximum of 23.5 +/- 6.2 ppm (mean +/- SD) from baseline values of 0.6 +/- 1.3 (p < 0.001) and plasma cotinine levels to a maximum of 9.5 +/- 4.5 nmol/L (mean +/- SD). The half time (T1/2 in minutes) for 99mTc-DTPA clearance rose from baseline 69.1 +/- 15.6 (mean +/- SD) to 77.4 +/- 17.8 (p < 0.05) after smoke exposure. No effect of 99mTc-DTPA scanning or of sidestream smoke was demonstrated on lung function.


CONCLUSIONS
We conclude that low level sidestream smoke inhalation decreases 99mTc-DTPA clearance acutely in humans. The mechanism of this unexpected result is not established but may include differences in constituents between sidestream and mainstream smoke, alterations in pulmonary microvascular blood flow, or changes in surfactant due to an acute phase irritant response.
Yates
D H
DH
Department of Respiratory Medicine, Concord Hospital, Sydney, NSW.
Havill
K
K
Thompson
M M
MM
Rittano
A B
AB
Chu
J
J
Glanville
A R
AR
D000328:Adult; D015824:Blood-Air Barrier / Q000502:physiology*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D010539:Permeability; D011650:Pulmonary Alveoli / Q000378:metabolism*; D015656:Respiratory Mechanics; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D014028:Tobacco Smoke Pollution; D016284:Technetium Tc 99m Pentetate