Challenges in the Management of Exercise-induced Asthma

William Storms, MD

Disclosures

Expert Rev Clin Immunol. 2009;5(3) 

In This Article

Challenges in Treating EIA & EIB

As with asthma, treating EIA and EIB involves nonpharmacologic, pharmacologic and educational components.

Nonpharmacologic Approaches

Warm-up. Exercise or physical activity is a trigger of asthma symptoms that cannot be avoided for most patients. However, an appropriate warm-up to 90% of the maximum heart rate prior to formal exercise can reduce the severity of EIA and, in some cases, may completely mitigate EIA symptoms. This refractory period of protection can last for as long as 2 h, but the effect is not consistent between individuals, or for the same individual on different days. Thus, warming up should be used to reduce the risk of EIA symptoms, but should not be relied on as a primary means of EIA prophylaxis.[3,6]

Environmental Control. It is recommended that all asthma patients avoid their environmental triggers that might increase airway hyper-reactivity and, thereby, increase susceptibility to exercise-induced symptoms. However, this may not be possible for all patients. Some recommendations for recreational athletes and children at play include the following:

  • For patients with seasonal allergies, exercise outdoors when allergens are at their lowest (i.e., in the early morning or evening).[2] Allergic patients should always be treated for their allergies. If outdoor exercise must be conducted during a period of high seasonal allergen counts (e.g., track meets in the autumn or spring), wearing a mask may be helpful. However, the use of a mask is not usually practical since many patients, particularly children, will not wear one;

  • Avoid pollution, both outdoors and indoors. Air pollution can be subtle. Air quality data from the Environmental Protection Agency (EPA) confirms that students attending schools located near to industry and in areas of high exhaust from traffic may be exposed to toxic levels of air pollutants while on school property, including playing fields.[101] Asthmatic patients should be counseled to avoid exercising when air quality is impaired and/or under extreme conditions of temperature and humidity.[6] However, avoiding high levels of air pollution was not possible for many of the athletes competing in outdoor events at the 2008 summer Olympic games in Beijing, China; news reports showed some competitors wearing masks. Exposure to indoor air pollutants can be difficult to control, particularly for swimmers and ice skaters, as chemical fumes tend to accumulate just above the surface of the water or ice. For these individuals, appropriate warm-up and pharmacotherapy are essential.[6] If symptoms cannot be controlled, the individual should look for other ways to enjoy exercise;

  • Avoid cold air. Appropriate warm-up and breathing through the nose to condition the cold air when exercising may be helpful. Wearing a mask or scarf over the nose and mouth may also help reduce the effects of cold air. However, individuals who remain sensitive to exercising in cold air despite warming up and appropriate pharmacotherapy should be advised to pursue other activities.[1,6,16]

Pharmacologic Therapy

Controller Therapy. The most commonly used pharmacologic therapy for EIB is an inhaled SABA, which can be used to both prevent and treat symptoms. For some patients, a SABA taken 10–15 min prior to exercise may be all that is needed to control their EIB. However, current guidelines recommend that SABAs, while effective first-line therapy for exercise-induced symptoms, should not be used more than three times a week because of the tolerance that develops with constant β2-agonist use.[1,3,16] Most patients with EIA who exercise frequently should receive regular controller therapy for asthma (e.g., inhaled corticosteroids [ICS] or montelukast). Controller therapy should also be considered for patients who have EIB and who exercise regularly (i.e., daily – either year-round or in-season). These patients may have an underlying airway inflammatory condition, even without expressing other asthma symptoms, and should be treated according to the recommendations of current practice guidelines.[1,3,16] In this case, controller therapy is used to minimize – ideally to prevent – exercised-related symptoms, as opposed to controlling daily asthma symptoms.[3] These recommendations are in agreement with the January 2008 IOC Consensus Statement, which states that athletes who use β2-agonists (either SABAs or long-acting β2-agonists [LABAs]) daily be told that 'their effectiveness to prevent EIB will diminish over time' and that 'frequent use of β2-agonists may increase the bronchoconstrictor response to exercise and allergens'.[102]

The goal of controller therapy for all patients with exercise-induced symptoms is to reduce BHR and enhance disease control overall by treating the underlying airway inflammation, thereby permitting a greater level of physical activity. The preferred controller treatment is an ICS but other options (e.g., montelukast, cromolyn or nedocromil) may better meet the needs of some patients.[1,2,16]

Through increased penetration and better distribution throughout the lungs, small-particle ICS formulations might provide added clinical benefit and address some of the subtle inflammatory changes associated with EIA and EIB. For example, because of a reduced particle size and reformulation into a solution, rather than a suspension, microfine hydrofluoroalkane beclomethasone dipropionate (HFA-BDP) shows comparable clinical efficacy to the older chlorofluorocarbon (CFC) formulation but at half the dose.[17,18] Approximately 55– 60% of inhaled HFA-BDP reaches the lung and distributes diffusely, reaching both central and peripheral airways, compared with 4–7% of CFC-BDP, which deposits primarily in the central airway.[18,19] HFA-BDP has been suggested to reduce small-airway remodeling[20] and, as such, might have an impact on epithelial changes associated with the mechanical shear caused by high minute ventilation. More studies are warranted. Deposition of HFA-BDP is good even in patients with a poor inhaler technique,[18] such as those who might use an inhaler 'on the run.'

Pre-exercise Medication. Pre-exercise medication usually involves treatment with an inhaled SABA 10–15 min prior to exercise. Another option is inhalation of the mast-cell stabilizer, cromolyn sodium, four to eight puffs 15 min prior to exercise. Cromolyn sodium can be used by itself or it may be added to a SABA in patients with more severe symptoms.[2] The leukotriene receptor antagonist, montelukast, an oral medication, may be helpful for some patients, particularly those who have difficulty using inhalers. For exercise, it should be taken once daily, at least 2 h prior to exercise.[16,21] Patients who are well controlled on their regular daily asthma medication may not always need pre-exercise therapy. For example, a well-controlled patient may be able to hike in warm weather, but might need premedication before exercising in cold, dry air. Nonetheless, no one can predict when symptoms will occur. As such, all patients with EIA or EIB should have a rescue inhaler easily available when exercising.

Albuterol metered dose inhalers (MDIs), propelled by CFCs, were phased out at the end of 2008 owing to their ozone-depleting chemistry. HFA-propelled MDIs are an ozone-friendly alternative with similar convenience and delivery systems. Albuterol HFA MDIs have been shown to deliver comparable doses to the lung and to have similar safety and efficacy profiles as the older CFC MDIs.[22] However, albuterol HFA MDIs may feel different on inhalation to some patients, owing to a more 'mist-like' spray. The new inhalers have been described as feeling 'more gentle' or 'warmer', probably related to a lower spray force than the CFC inhalers.[23] This may be preferred for some patients, as the gentler spray is less likely to cause coughing.

As noted above, daily use of SABAs (or LABAs) should be avoided owing to the possibility of tachyphylaxis and partial loss of the effectiveness of the β2-agonist over time. Tolerance can develop, even when β2-agonists are used in combination with an ICS.[3,16] Patients who exercise daily and need premedication may need to start or increase appropriate controller medication in order to minimize their usage of β2-agonists.[16,24]

Treating Breakthrough Symptoms. β2-agonists also are the best studied and most commonly used medications for relieving breakthrough symptoms of EIA (and EIB), and current guidelines recommend that every asthma patient has a SABA inhaler for acute symptoms.[2,16] By using a SABA and reducing the intensity of their activity for a short period of time, the average noncompetitive athlete with EIB can usually continue to exercise even after experiencing breakthrough symptoms. Inhaled SABAs have an almost immediate onset of action that lasts up to 4 h. LABAs are not recommended for treating breakthrough symptoms.[2,16]

For the patient with persistent asthma, breakthrough symptoms or poor endurance can be an indication of poor control and the need to increase daily controller therapy. Appropriate controller therapy should minimize the need for reliever medication.[2,16] Consultation with a respiratory specialist should be considered if the patient does not respond to treatment.

Monitoring EIA

Patients with EIA need to be monitored according to the guidelines for managing asthma, while those with EIB can be followed up, by phone or office visit, sooner, since the medications for EIB alone work quickly.[2] Follow-up should evaluate whether a step-up or step-down in therapy is needed, the patient's technique for using his or her inhaler (as appropriate) and whether there are any comorbid conditions to be addressed. EIA symptoms may become more prevalent at certain times of the year – specifically, in the winter owing to cold air, during the patient's allergy season, when humidity changes, during times of stagnant air and pollution, following a viral respiratory infection, or with allergic rhinitis. At these times, airway hyper-reactivity and the risk of breakthrough symptoms can increase and the patient may need to adjust his or her therapy. Treatment changes may be needed whenever the patient changes the intensity of their exercise. Temporarily limiting activity or changing sports or type of exercise can be considered as a last resort during times of severe symptoms; most patients should be able to exercise at their maximum level with proper treatment.

Patient Education

Patient education for EIA should include discussion of which activities are most likely to cause symptoms and under what conditions, thereby increasing the patient's awareness of his or her symptoms and how they respond to various environmental triggers. Discussion of how or when to avoid environmental triggers is critical, and should include allergens, irritants and air pollution.

Information should also be provided on the role of pharmacotherapy, particularly controller medications, in treating EIA, and consideration of nonpharmacologic approaches to minimizing EIA symptoms. Discussion of nonpharmacologic approaches should include demonstration of appropriate warm-up techniques and, for some patients, discussion of nasal breathing to warm and humidify the inspired air. Patients should likewise be aware of any nasal symptoms or other cormorbidities (e.g., GERD and upper respiratory infections) that may increase the severity of their EIA, and should learn how to treat them promptly and appropriately.[1,3]

Patients should recognize that different levels of exercise and training require a step approach to managing EIA; medications need to be increased or decreased according to the intensity of the exercise. Just as training for a marathon differs from warming up for a five-mile jog, so too does managing EIA for these circumstances. Patients and physicians should know that even Olympic athletes who have asthma can compete, and that every patient should be able to perform at his or her desired level of activity with proper medical therapy.

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