Exercise Induced Asthma in Schoolchildren

Male: What is exercise-induced asthma? Michael Marcus: Exercise-induced asthma is a problem where patients who reach a certain level of exercise will start having difficulty breathing and tightness of the chest or cough and these symptoms will then limit their ability to be active or to compete at the same level of other people of their same age. Male: Why does that happen? Michael Marcus: It happens because the lungs are having an abnormal response to the exercise level. Normally, when you or I would exercise, what occurs is that the smooth muscle in the airways of the lungs relaxes so that more air can come into the lungs to help support the exercise level that we’re trying to achieve. And patients with exercise-induced asthma, the exact reverse happen, that is when we reach that exercise level, the smooth muscles of the lungs constrict narrowing the airways and limiting the amount of air that can come into the lungs. Male: How can you diagnose this correctly? Michael Marcus: The best way to diagnose this is to use very specific types of exercise testing. We always start with a good history of exactly what is happening during the exercise period, the timing of the breathing difficulty and the symptoms the patient has because we need to identify whether the patient is having breathing difficulty because they are truly having a medical problem or that they merely have poor conditioning and need to exercise more. Once that history suggest that we may be dealing with an exercise related breathing problem, we then put them through an exercise challenge test where we do breathing test before an exercise period then put them on a type of exercise such as a treadmill or an exercise bike for a period of 10 or 15 minutes, really pushing them to the limit of their exercise tolerance. After that exercise period, we then continue to monitor breathing tests for a 30-minute period and if the patient has exercise-induced asthma, the lungs will narrow during this 30-minute period with a decrease in the lung function. If the patient does not have this narrowing then we know that the symptoms they’re having are not caused by exercise-induced asthma. Male: Are there any conditions that can mimic exercise-induced asthma? Michael Marcus: There are several and in fact, a study was done which showed that less than 50% of patients who are referred for testing actually are proven to have exercise-induced asthma, that’s why the testing is very important. Some of the symptoms that might mimic it would be gastroesophageal reflux, acid reflux. When some patients exercise, the acid comes up from their stomach and this can lead to a feeling of tightness in the chest which the patients perceive is coming from the lungs, yet it’s really coming from the food pipe. That acid could also get up into the throat causing some spasm of the muscles of the throat leading to breathing difficulty. Patient might also have allergies causing breathing difficulty and the breathing difficulty may be occurring outdoors when they’re exposed to pollen in their allergy season. Yet, during the rest of the time a year, they don’t have problems. This would be more allergy mediated. There are also several other potential causes of exercise-induced asthma, type symptoms where they don’t truly have the disease but I believe the most common cause of breathing difficulty in patients who don’t have exercise-induced asthma is merely poor cardiopulmonary conditioning. In other words, the patient is out of shape and is reaching an exercise level that their body hasn’t prepped for, and so, they’re getting fatigued and tired and having difficulty of breathing. In that situation, the breathing test will be normal and the cure is to do more exercise but to do the breathing test tells us it’s safe to do more breathing, more exercise. Male: There are some cardiac conditions which can mimic this and kind of silent and they put through athletic activity and that might be in large, whatever, whatever the condition is, how can we exclude that is a possibility? Michael Marcus: Heart problems are a reason why some patients might have tightness in the chest or easy fatigue with exercise, without question a cardiac evaluation is important, especially if that exercise test is normal. The cardiac evaluation starts with a good exam, listening to the hearts sounds carefully, an EKG, electrocardiogram and if necessary, an echocardiogram so that we have a good picture of what the heart looks like.