A modified single breath nitrogen test was used in an emphysema screening center to assess the value of the analysis of the alveolar plateau in the early diagnosis of airway obstruction. Predicted values for the slope of the alveolar plateau (the increase in nitrogen concentration per 1,000 ml) were first constructed using a population of 134 nonsmoking males and 203 nonsmoking females. Data obtained from 530 cigarette smokers attending the screening center were then compared with these predicted values and with predicted values for closing volume, expressed as a percentage of vital capacity, and closing capacity, expressed as a percentage of total lung capacity, derived from virtually the same population of nonsmoking adults. Of the cigarette smokers, 47% had an abnormal slope of the alveolar plateau, 44% had an abnormal ratio of closing capacity to total lung capacity, 35% had an abnormal ratio of closing volume to vital capacity, and 11% had an abnormal forced expiratory volume in one sec. When the slope of the alveolar plateau, the closing capacity, and the closing volume were taken in conjunction, 64% of the smokers were found to have one or more abnormal test results. The practical importance of this technique may be that it is suitable for use as a screening test and that the one test can be used to evaluate 3 very different parameters of lung function, namely, the uniformity of alveolar ventilation, the lung volume at which dependent lung zones cease to ventilate, and residual volume.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Dec 1 1973|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine