The nature of the increased lung volume in asthma

Thirty-two asthmatic patients were studied during an acute exacerbation and subsequently during remission. Four were found to increase their Total Lung Capacity during acute exacerbation when measured by a closed circuit helium dilution technique. However, concomitant use of a radiologic method for estimating total lung capacity showed no increase in TLC. It is suggested that the difference is an artifact due to helium swallowing or gas leak.