Lung Function in Asymptomatic Cigarette Smokers—The Single Breath Nitrogen Test

Abstract
The modified single breath nitrogen (SBN) test and simple spirometry were used to study the lung function (LF) of 101 asymptomatic, cigarette smoking and 20 nonsmoking men aged 18-39 yr. Abnormal LF was demonstrated in 39% of smokers. An abnormal SBN test was found in 28% of the light and 56% of the heavy smokers but only 3% were spirometrically abnormal. Only 1 non-smoker had an abnormal SBN test. Closing volume and slope of the alveolar plateau, which are both measured from the SBN test, correlated poorly suggesting that the abnormality caused by smoking may differ among smokers. The SBN test is a simple test which is sensitive enough to detect LF abnormalities in young smokers. The significance of the detected abnormalities in relation to the development of chronic obstructive lung disease is not presently known.