ATS Pulmonary Function Laboratory Manual

ATS Pulmonary Function Laboratory Management & Procedure Manual | 3rd Edition

Effective Date: 2014 Version #1

Chapter 14

Procedure Name: Exercise Challenge Test

Purpose or Principle The purpose of this airway challenge test is to determine whether the patient has exercise-induced airway nar- rowing. The identification of hyperreactive airways using an exercise stimulus can play an important role in the diagnosis and management of asthma (1–3). The preferred term for bronchoconstriction that occurs during or after short-term exercise is exercise-induced bronchoconstriction (EIB). Although historically referred to as exercise- induced asthma (EIA), it is probably more appropriate to call this condition EIB, because the response to exercise is actually bronchoconstriction and not all people with asthma have EIB (4–6). However, EIB has been reported to occur in up to 90% of children with asthma in some selected series (1, 7, 8), but population-based studies indicate a prevalence of about 50% (9). Several cross-sectional screening studies have found rates of EIB between 10 and 18% in the general population (10, 11). Data from published studies suggest that the severity of asthma correlates with the severity and degree of EIB (1–3). Atopy is a recognized risk factor for EIB, suggesting that patients with allergic rhinitis or atopic dermatitis with exercise-related symptoms may have EIB (12–14). The pathophysiology of the airway response to exercise has been highly debated (1, 2, 15–17). One theory pos- tulates that the initiating stimulus for bronchoconstriction is the increased ventilation induced by exercise, which induces airway heat loss due both to convection and evaporation. Convective heat loss is related to the heat capac- ity of gas, and evaporative heat loss is related to the heat of vaporization of water (18). Direct measurements have demonstrated temperature changes in the airway mucosa in humans during exercise (19, 20). There is also strong evidence that EIB is a manifestation of airway inflammation, since patients with EIB, relative to individuals with asthma without this syndrome, have higher levels of cysteinyl leukotrienes and 8-isoprostanes (21–23, 82). The level of exhaled nitric oxide (eNO) is also correlated with the severity of EIB (24–29). Some studies indicate that EIBmay result from injury to the airways, since this syndrome occurs frequently in elite athletes, without prior history of asthma, after exposure to training environments in which they inspire large volumes of cold dry air (30–35). Indications The indications for exercise challenge testing are provided in Table 14.1, and the relative contraindications are pre- sented in Table 14.2. The list of possible contraindications may not be all-inclusive and therefore is not a substitute for clinical judgment.

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