Exercise-induced asthma
Exercise-induced asthma is a feeling of shortness of breath, with the presence of cough, wheezing, and chest tightness after physical effort.
Normally the bronchial tree responds to exercise with increasing radius of the interior of the bronchi (bronchodilation), but those affected by exercise-induced asthma occurs otherwise narrow and produces bronchoconstriction.
CAUSES
The exercise-induced asthma (EIA) is due to cooling and drying air relative (loss of H2O) by increased ventilation during exercise. The cooling and drying cause changes in the osmolarity of the mucosa, leading to one hand, there is a mast cell degranulation with release of mediators, and second, to the occurrence of direct vagal stimulation. The result is the emergence of bronchoconstriction. Cold air inspired Low humidity of inspired air, Loss of heat from the air. Exercise-induced asthma
Symptoms
The defining characteristics of the IEA are:
Can occur at any age, and is as common in adults and children. Fleshy settings (wide body constitution) are prone.
May appear isolated or associated with any clinical form of bronchial asthma. In most asthmatics, exercise causes broncho constriction.
The severity of EIA is not predictable from baseline function. Patients with normal lung function at rest may have important IEA.
Phase characteristics of the IEA:
Initial broncho dilation (asymptomatic). As in non-asthmatics, in patients with asthma exercise initial bronchodilation occurs without symptoms.
Clinical bronchospasm. After 5-10 minutes after the effort began, when the heart rate reaches about 160 beats per minute, appears bronchoconstriction.
Recovery phase. Between 30 and 60 minutes after starting the exercise, it begins a return to normality in bronchial caliber and dyspnea disappears.
Refractory period. In more than half the cases of EIA, there is a period of 2-4 hours, during which it will revert to the bronchospasm, although it should be continue to exercise. The refractory period is due to depletion of mediators of bronchoconstriction and / or generation of bronchodilator prostaglandin (PGE2) during exercise. The refractory period can be induced by preheating, and used for the asthma is not impaired athletic performance.
The EIA can be prevented by inhalation or after taking certain medications. Are used for this purpose ß2-mimetic action short and long cromolyn, and leukotriene inhibitors.
Diagnosis
A history of cough, dyspnea, wheezing, chest tightness or performance problems during exercise suggests IEA.
Confirmation of the diagnosis usually requires an exercise test, which can be made:
Under laboratory conditions, using treadmill or bicycle ergometer and heart and respiratory monitoring. The child should run in a sufficiently intense to increase in heart rate by 80% or less, for 4-6 minutes.
In outdoor race, trying to reproduce the situation that causes the symptoms. We evaluate the distance covered in 10-12 minutes and relevant incidents during this test.
In either case, are performed spirometry before and after exercise at intervals of five minutes and for 20-30 minutes. A 15% decrease in FEV, is the criterion for diagnosing exercise-induced asthma (EIA).