Pathophysiology of EIA & EIB
An underlying pathology of asthma is airway inflammation. While the mechanism is not completely understood, in the patient with EIA, the airway physiological response to exercise triggers or exacerbates the underlying inflammation of asthma.[1,3]
Evidence indicates that alterations in airway humidity and temperature contribute to EIA. Vigorous physical activity is associated with increased inhalation by frequency and volume; the increased ventilatory rate results in evaporative changes affecting the respiratory mucosa. This airway drying leads to increases in the osmolarity of respiratory epithelial cells and subsequent inflammatory changes, including the activation of epithelial cells and airway mast cells, and the release of histamine, leukotrienes and other chemokines. Additionally, vascular dilation of small blood vessels involved in rewarming the airways following exercise may contribute to congestion and further release of inflammatory mediators.[3,8] In patients who have asthma, these changes in airway osmolarity and temperature are believed to trigger the characteristic symptoms of BHR. Increased levels of airway inflammatory cells and mediators have been observed in exercising athletes with and without BHR.[9,10]
Exercise-induced changes in airway function are exacerbated in cold and/or dry air, possibly reflecting the involvement of additional physiologic pathways (e.g., cholinergic stimulation, pulmonary vasoconstriction and secondary reactive hyperemia).[4,8]
Expert Rev Clin Immunol. 2009;5(3) © 2009
Cite this: Challenges in the Management of Exercise-induced Asthma - Medscape - May 01, 2009.