Exercise-induced airway obstruction.

Many previous discrepancies and conflicts concerning the pathophysiology of EIAO have been explained or reconciled by the observation that respiratory heat loss and concomitant airway cooling relate directly and probably causally to both the occurrence and magnitude of the airway obstruction that develops. Recent measurements have documented and quantitated observations made centuries ago. Controversy continues concerning the role of mediator release and the relative contribution of vago-vagal reflexes to the response induced by airway cooling. Recent attempts to study the effects of cooling on both the responsiveness and metabolic processes of airway smooth muscle may well ascend the phylogenetic scale to the intact organism, eventually allowing the testing of hypotheses raised along the way. Meanwhile, we think it likely that airway cooling and the response to it will represent another example of nonspecific airway responsiveness, and that the links between this stimulus and the subsequent response will be multifactorial. The relative roles and interactive potentials of diverse processes will make the next step in understanding difficult, though not impossible.