Fawzia abo aliProf.of allergy &clinical immunology Faculty of medicine Ain shams university
Exercise-induced asthma & bronchospasm• Definition: Airway obstruction, and hyper responsiveness, triggered by exercise - EIA: exercise induces symptoms of asthma in patients who have asthma (90% of patients) - EIB: exercise induces bronchospasm in patients without chronic asthma, for example, an elite athlete.
physical activity is the second leading cause of airway constriction after upper respiratory tract infections. EIA: symptoms start after exercise, peak 8 to 15 minutes after exercise and spontaneously resolve in 60 minutes. EIA is diagnosed by a 15% decrease in FEV1. EIA is most frequently seen in children and young adults because of their high levels of physical activity.
Epidemiology EIA affects: 90% of asthmatics 40-50% of patients with allergic rhinitis 3-13% of the general population 10-20% of athletes
Asthmogenic exercise: The type of exercise performed directly affects the intensity and duration of an EIA episode. Asthmogenic sports are characterized by sustained hyperpnea (deep, rapid breathing during intense, prolonged aerobic activity) - basketball - cycling - running - hockey
Less asthmogenic sports:sport that produces intermittent bursts of hyperpnea, such as baseball, weight lifting or tennis. In addition, activities such as bike-riding and swimming are less likely to induce EIA than running.Swimming appears to be the least asthmogenic sport, which may in part be related to the inhalation of humidified air.
The sequence of events in EIA is characteristic: 1. Airways dilate during exercise (FEV1 increases by 5% in normal people). 2. When the exercise is over, airway obstruction begins and progresses until it reaches a peak in 5-10 minutes 3. Spontaneous resolution occurs in 30 minutes. The tendency toward spontaneous remission is a hallmark of EIA: one needs only to reverse the acute event and the patient will then remain free of symptoms.
Pathogenesis There are 2 theories for EIA pathogenesis: thermal osmoticThermal hypothesis, there is no role for biochemical mediators. Osmotic theory has been gaining a wider acceptance in recent years.
Several studies have noted an increase in the concentration of cysteinyl leukotrienes (CysLTs) in the airways of patients with EIB. a recent study found that the fraction of exhaled nitric oxide (FENO) is elevated in asthmatic patients with EIB, Angiopoetin 2, a mediator that enhances microvascular permeability, is increased in the airways in EIB Mast cell infiltration of the airways has also been implicated in EIB.
Duration of EIA Symptoms• Symptoms begin during or after exercise and usually worsen 5-20 minutes after stopping activity• Some people experience a “late-phase reaction” 4- 12 hours after exercising. Symptoms usually less severe.
Diagnosis Exercise-induced asthma can be diagnosed by history only and formal testing is usually required only in competitive athletes. Points in the patient history: - Onset during or after exercise - EIB not affect first 5 minutes of exercise - Symptoms duration longer than 5 minutes
Testing for EIA - FRAST: free running asthma screening test - Treadmill exercise test - Cycling FRAST A simple screening test in children: 1. Establish a baseline PEF. 2. Have the child run continuously for 7 minutes (same duration as treadmill exercise test), OR have the child run until he/she has symptoms. 3. Check PEF, more than 15% decrease in PEF is diagnostic of EIA.
Exercise Challenge TestDiagnosis: 10 - 15% reduction of PEFR or FEV1 after 6 minutes treadmill exercise at 85- 90% maximal heart rate
Bronchial provocation tests used to diagnose asthma in athletes• Methacholine challenge• Exercise challenge• Mannitol inhalation• Eucapnic voluntary hyperpnea• Hypertonic saline challenge
Management Non-pharmacological treatment: - Ensure patient has taken asthma medicine• Warm-up and Cool down periods• Hydrate before, during and after exercise• Check pollen and air quality• Cold Weather• - breath through the nose
Pharmacological treatment Mnemonic for drugs used for treatment of EIB - CLIMB: Cromolyn Leukotriene receptor antagonist (LTRA), montelukast Inhaled steroids (ICS) Mast cell stabilizers other than cromolyn Beta-2 agonists, albuterol
In conclusion• EIA is common affecting10-20% of the general population, and up to 90% of unselected asthmatics• It is easily managed with warm-up and cool- down, nasal breathing and pre-medication.• Cough post exercise best predictor for positive exercise challenge test• 90% can be successfully treated with pre exercise MDI• Return to play usually safe• Control of Exercise-induced asthma affords a healthy lifestyle in which exercise is performed without restrictions.
Resources• American College of Allergy, Asthma, and Immunology – http://www.acaai.org• American College of Chest Physicians – http://www.chestnet.org• American Thoracic Society – http://www.thoracic.org• The Centers for Disease Control and Prevention – http://www.cdc.gov/asthma• National Asthma Education and Prevention Program – http://www.nhlbi.nih.gov/about/naepp/• Asthma and Allergy Foundation of America – http://www.aafa.org• American Lung Association – http://www.lungusa.org• American Academy of Allergy, Asthma, and Immunology – http://www.aaaai.org• Allergy and Asthma Network/Mothers of Asthmatics, Inc. – http://www.aanma.org