August 1997
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Salmeterol may be particularly effective for children who have
gym class in the morning.
SAN DIEGO — A child with exercise-induced asthma who does not readily respond to two puffs of an aerosol inhaler may require unusual treatment modalities.
"This particularly becomes a problem in the elite athlete," said Laurie J. Smith, MD, assistant chief of the allergy clinical immunology department at Walter Reed Army Medical Center in Washington, D.C.
"These individuals choose to push themselves to peak endurance. They are asking a lot of their bodies. Very often, a routine asthma therapy is not going to manage them."
Smith, who spoke here at the recent meeting of the American Academy of Pediatrics, shared the example of a 15-year-old boy who swims for his high-school swim team and is training for a national competition. The swimmer relates that his asthma is not controlled by two puffs of albuterol during his long training sessions. Furthermore, he denies experiencing asthma symptoms any other time.
"This is an interesting case because many of us are taught that swimming is a good exercise for asthma and, typically, will not cause exercise-induced asthma," said Smith. However, any arm exercise can be asthmogenic. "So it simply depends on whether the moisture and warm air counteract the activity."
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Factors That Affect Exercise-Induced Asthma |
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Intensity, duration, stress and environment are four factors that can render the traditional two-puff therapy insufficient.
"The longer you are out from taking medication, the less efficacious your average inhaled bronchodilator will be in terms of blocking exercise-induced asthma," noted Smith. Consequently, for competition that lasts more than an hour, "the two puffs that were taken at the very beginning simply may not be sufficient to persist."
In addition to taking a careful history and a physical examination, spirometry is extremely helpful in identifying abnormal lung function. "If it's not normal, it must be normalized before you are going to be successful," said Smith.
Many cases of inhaler failure stem from inadequate inhalation technique. If the technique is proper, Smith adds a cromolyn drug. She recommends two puffs of a b-agonist, along with four puffs of a cromolyn, 15 to 30 minutes before exercise.
For children who do not respond effectively to such treatment, Smith suggests considering further testing: peak-flow monitoring at the exercise site, inspiratory/expiratory flow volume loops and even an exercise challenge.
"The reason for this is because symptoms may be masquerading as exercise-induced asthma, when in fact they are not," she said, citing cases of panic attacks and atypical seizures. "There is the entity of vocal cord dysfunction which can present like asthma, but will simply not respond to inhalation of any asthma medications."
In situations of uncertain diagnosis and normal office spirometry, Smith prefers that the athlete measure a peak flow in the field during symptoms. However, for the test to be valid, "he must measure his peak flow, morning and evening, for a time so that he gets use to it. He has to do it correctly, he has to mark it down and he has to find out what normal is for him," she stated. "You cannot have a spontaneous valid peak-flow measure."
If the peak flow is 400 both before exercise and during symptoms, "clearly, you are not dealing with exercise-induced asthma," she said.
Salmeterol (Serevent, Glaxo Wellcome) is a long-acting b-agonist that lasts about 12 hours. Although indicated for children older than 12, "I have used it in younger children with precaution," said Smith. In these cases, "my greatest criteria is my perception of the individual that I am giving it to. The agent must be used correctly and cannot be used more than once every 12 hours."
Remind parents and children that salmeterol is a prophylactic drug, and cannot help relieve acute episodes.
Salmeterol is particularly effective in situations where the child has morning gym, in which case the parent can give the agent prior to school, and for prolonged exercise periods, such as swimming and hockey, said Smith. Regardless, "the drug must be prescribed with a short-acting rescue agent."
Adding inhaled corticosteroids in moderate to high doses may also be warranted for episodic unstable asthma. Two other treatments to consider are theophylline and inhaled ipratropium.
A non-drug manipulation is a pre-exercise warm-up: five minutes (80% maximum exertion) every 40 minutes or two to three minutes followed by a three-minute rest. "There is evidence that if you exercise to below the asthma-trigger threshold, you can induce a refractory period," said Smith.
Breathing through the nose, breathing warm humidified air and/or avoiding hyperventilation during warm-up may also lessen exercise-induced asthma.
"When children with asthma really want to compete and participate, they may end up on five or six or seven medications. You can almost always get them to the point where they can participate," said Smith.
For more information:
- Mendelson LM, Smith LJ. Office allergy for the pediatrician. Presented at the American Academy of Pediatrics. May 10-13. San Diego.
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