• The normal range for dynamic expiratory lung volume in healthy adults is unknown. • In a group of 27 healthy male occupational divers, we observed a mean decrease of 14.7% in EELV at maximum load compared to baseline. • The upper limit of normal for the change in EELV from baseline to maximum load in this group was at least -5.8%. • Changes in EELV smaller than this require further diagnostic evaluation before a diver can be deemed fit to dive. In respiratory patients, the end-expiratory lung volume (EELV) during exercise (dynamic EELV) is measured to quantify dynamic hyperinflation. In COPD patients, an increase in EELV of less than 5% is considered normal. However, whether this holds for healthy individuals remains to be determined. This study aimed to determine the upper limit of normal (ULN) for changes in dynamic EELV in a healthy population. The percentage changes in EELV were measured in 27 healthy Caucasian male divers before and during maximal cycle exercise testing. In addition to EELV, spirometry was also performed. The ULN was estimated using the bias-corrected and accelerated bootstrap resampling method. All spirometry data were within the normal Z-scores. A significant mean decrement of at least 14.7% in EELV was found at maximal load. This yielded a ULN of -5.8%. When corrected for outliers, the ULN was -7.1%. In a healthy Caucasian male diving population, the ULN for dynamic EELV is at least a change of -5.8%, preferably -7.1%, compared with the EELV at rest. Any change smaller than these values may warrant further diagnostic evaluation to assess potential diving-related risks.
Ooij et al. (Wed,) studied this question.