Part 2: Differential Diagnosis and Management of EIB
The symptoms of EIB are mimicked by other conditions and diseases. It thus becomes essential and imperative to rule out other diagnoses. For instance, obesity and vocal cord dysfunction can mimic asthma as well as EIB. Generally, EIB is associated with poorly controlled asthma, though in some cases exercise may be the only trigger for asthma.
About 80% of obese individuals complain of exercise-induced symptoms. Hence the need to determine whether the diagnosis is EIB or not.
Differential diagnoses should take into consideration:19, 20
- obesity and general poor physical fitness
- vocal cord dysfunction
- upper airway obstruction
- anxiety associated dyspnea
- cardiac abnormalities
- supraventricular tachycardia
- pulmonary malformations
- pulmonary abnormalities
- chest wall or other musculoskeletal abnormalities
Obesity affects lung mechanics. It increases contractibility and bronchial smooth muscle responsiveness (BHR), and makes breathing more difficult, resulting in symptoms that mimic EIB. Deconditioning may also be correlated with obesity and thus affect breathing. It has been shown that weight loss can improve pulmonary mechanics in obese patients.21
Overweight adolescents with poorly-controlled asthma reported significantly more EIB-related symptoms than those with well-controlled asthma.22
Vocal cord dysfunction is a functional disorder where there is paradoxical closure of the vocal cords on inspiration which results in dyspnea, and shortness of breath.
Hyperventilation due to anxiety, stress and negative emotions can result in symptoms similar to those of EIB.23
Airway and cardiac abnormalities may impair pulmonary mechanics and result in wheeze and mimic EIB.
Asthma and EIB
Next to viral infections, exercise is the most common EIB trigger for patients with asthma, with the EIB level influenced by the level of severity and control. About 90% of individuals with asthma report symptoms induced by exercise.24 The diagnosis of EIB is considered when exercise is the only trigger for bronchoconstriction. Because of the biphasic nature of asthma, EIB symptoms often start again and peak 8 to 15 minutes after exercise, and then resolve spontaneously in about 60 minutes. Repetition of exercise in the 3-hour refractory period after recovery causes less bronchospasm.25, 26
A study of 1517 individuals (250 children, 266 adolescents and 1001 adults) with asthma showed that individuals of all ages whose asthma was either not well controlled or very poorly controlled (defined according to the Expert Panel Report 3) had significantly more EIB related symptoms than individuals with well controlled asthma.22
ffects of EIB
An EIB survey27 showed that the symptoms of EIB caused avoidance of activity in
- 46 % of adults
- 26% of children
- 39% of all asthma patients.
The survey also showed that EIB affected both participation and performance in sports. Table 5 lists the effect of asthma on sports from participation through performance.
Table 5: Effect of asthma on sports
The survey also found that 80% of patients with current asthma report symptoms of EIB both during and after physical activity that includes play, exercise and sports.
EIB also affects quality of life. While about one in five adults without asthma reported that their health interfered with activities, the number of adults with asthma who did so was more than double. A comparison of these two groups indicated limitations as shown in the table below.
Table 6: Comparison of restricted activities with asthma and non-asthma groups
Almost 40% of asthma patients who had symptoms but were not given a diagnosis, as well as 40% of those who had received a diagnosis, reported that they had difficulty keeping up with individuals of corresponding ages in both sports and physical activities. Table 7 indicates the level of interference in relation to symptoms.
Table 7: Effect of EIB on quality of life
The most telling part of the survey was the connection between symptoms and the emotional burden of asthma. Even patients without symptoms felt negative emotions related to their asthma. See Table 8.
Table 8: Reported emotions in asthma
Management of EIB
EIB can be managed both pharmacologically and non-pharmacologically. In asthma, it is essential that the asthma be brought under control using appropriate therapy while including non-pharmacological approaches. See Table 9. EIB can be successfully managed with training and the appropriate use of medications such as beta-agonists, leukotriene modifiers and inhaled corticosteroids.
Table 9: Management of EIB
The short-acting beta agonist (SABA) should be inhaled 15 minutes prior to exercise. Just as all individuals with asthma should have their SABA inhaler available at all times, so too should those individuals with EIB. SABA inhalers should always be immediately at hand, even for athletes, since exercise performance is not enhanced by SABAs.28
If the SABA is required daily or more than once a day, then the ATS Guidelines recommend adding a controller agent such as a long-acting beta agonist (LABA). However, there is a strict warning against using LABA as monotherapy. For patients who are symptomatic despite pre-medicating with a SABA, an inhaled corticosteroid (ICS) is recommended. The ICS will take anywhere from two to four weeks to achieve maximum effectiveness. ICS should not be used only before exercise. Yet another choice is the Leukotriene receptor antagonist (LTRA), that can be used daily. Mast cell stabilizers can be used in a manner similar to SABA. Antihistamines are not recommended for individuals who do not have allergies.29
All individuals with EIB (those with and without asthma), should be encouraged to exercise and to prevent an exacerbation by pre-medicating followed by a slow warm up prior to exercise, and a slow cool down after. The slow warm up includes:
- 5–10 minutes of stretching
- 5–10 minutes jogging
- a few 30-second sprints
The slow cool down is the warm up in reverse, beginning with the sprints and ending with stretching.
The avoidance of triggers is critical both in EIB and to maintain control of asthma. Non-pharmacologic treatment and environmental control also involve the type of exercise that is least likely to induce an asthma exacerbation, such as swimming, team games, calisthenics and intermittent exercise. An environment that is warm and humid is also beneficial in reducing BHR. Individuals who have asthma and BHR can benefit from exercising indoors on days with high pollen counts, and avoiding dry cold surroundings. If exercising in a cold environment, wearing a scarf that covers the nose and the mouth, or use of a mask, will minimize heat and moisture lost through mouth breathing and prevent EIB.
Salt too has a role to play in EIB. In the diet, salt is known to speed weight gain, increase plasma volume and urinary output in individuals with asthma. Studies have shown that, in patients with asthma, an increase in dietary salt increases airway inflammation after exercise, while a reduction in dietary salt reduces it. The mechanism by which salt modifies EIB is not yet known but salt is known to change vascular pressure and volume, and this may have an effect on airway function after exercise.30, 31
Another non-pharmacological approach is to increase the use of fish oil in the diet. A diet rich in fish oil improves pulmonary function and attenuates the EIB response. It has been shown that the addition of fish oil reduces medication use and airway narrowing.32 Dietary supplementation with Lycopene is not recommended but supplementation with ascorbic acid is suggested.29
While it seems obvious that intense exercise should increase bronchial hyperresponsiveness (BHR), it appears paradoxical that exercise itself may reduce the risk for BHR. An investigation of more than 5000 adults who participated in the European community Respiratory Health Survey found that BHR was associated with decreased physical activity.33 In fact, both the duration and frequency of physical activity were inversely related to BHR. As such, regular physical activity may have an anti-inflammatory effect on the airways34 for it is known to reduce systemic inflammation as evinced by markers of inflammation.
BHR is a problem common to patients with and without asthma. Because it is linked to exercise, resulting in EIB, the automatic patient response is to reduce the amount and intensity of exercise. Yet physical activity is beneficial, particularly for the patient with asthma. It has been shown to reduce BHR in children with asthma (but not in children without asthma).33 Increasing the intensity and duration of exercise also lessens BHR in adults, even after taking into account gender, body mass index, smoking and the presence or absence of asthma.
Part of the solution to EIB then is to actually exercise after controlling the asthma. This would eliminate physical inactivity as a risk factor for asthma – a simple solution with far-reaching effects. Of course, the benefits of exercise are not limited to those who suffer from asthma. In the area of public health, exercise has implications for both morbidity and mortality and may be today's equivalent to the fountain of youth.
BHR: Bronchial hyperreponsiveness
EIA: Exercise Induced Asthma
EIB: Exercise Induced Bronchoconstriction
FEV1: Forced Expiratory Volume in One Second
ICS: Inhaled Corticosteroid
LABA: Long-acting beta agonist
LTRA: Leukotriene Receptor Antagonist
SABA: Short-acting beta agonist
19. Weiss P, Rundell KW. Imitators of exercise-induced bronchoconstriction. Allergy Asthma Clin Immunol. 2009 Nov 17;5(1):7. doi: 10.1186/1710-1492-5-7.
20. Weinberger M, Abu-Hasan M. Pseudo-asthma: when cough, wheezing, and dyspnea are not asthma. Pediatrics. 2007; 120(4):85-864
21. Karason K, Lindroos AK et al. Relief of cardiorespiratory symptoms and increased physical activity after surgically induced weight loss: results from the Swedish Obese Subjects Study. Arch Intern Med 2000; 60: 1797-1802.
22. Ostrom NK, Parsons JP et al. Exercise-induced bronchospasm, asthma control, and obesity. Allergy Asthma Proc. 2013; 34(4):342-8. doi:10.2500éaap.2013.34.3674
23. Rietveld S, van Beest I. Roller coaster asthma: when positive emotional stress interferes with dyspnea perception. Behav Res Ther. 2007;45(5):977-987.
24. Maurer M, Simonett D, Brutsche MH. Challenge of exercise-induced asthma and exercise-induced bronchoconstriction. Expert Rev Respir Med 2009; 3(1):13-19.
25. Randolph C. An update on exercise-induced bronchoconstriction with and without asthma. Curr Allergy Asthma Rep. 2009; 9(6): 433-438.
26. Randolph C. Exercise-induced bronchospasm in children. Clin Rev Allergy Immunol. 2008; 34(2):205-216.
27. Exercise Induced Bronchospasm (EIB): A landmark survey of asthma patients. www.eiblandmarksurvey.com. Accessed May 8, 2015
28. Carlsen KH, Anderson SD et al. Treatment of exercise-induced asthma, respiratory and allergic disorders in sports and the relationship to doping: Part II of the report from the Joint Task Force of European Respiratory Society (ERS) and the European Academy of Allergy and Clinical Immunology (EAACI) in cooperation with GA(2)LEN. Allergy 2008; 63(5): 492-505. Abstract.
29. Parsons J, Hallstrand TS et al. An Official American Thoracic Society Clinical Practice Guideline: Exercise-induced Bronchoconstriction. Am J Respir Crit Care Med 2013; 187(9): 1016-1027.
30. Mickleborough TD, Lindley MR, Ray S. Dietary salt, airway inflammation, and diffusion capacity in exercise-induced asthma. Med Sci Sports Exerc. 2005;37(6):904-914.
31. Mickleborough TD, Fogarty A. Dietary sodium intake and asthma: an epidemiological and clinical review. Int J Clin Pract. 2006;60(12):1616-1624.
32. Mickleborough TD, Rundell KW. Dietary polyunsaturated fatty acids in asthma- and exercise-induced bronchoconstriction. Eur J Clin Nutr. 2005;59(12):1335-1346.
33. Shaaban R, Leynaert B, Soussan D, et al. Physical activity and bronchial hyperresponsiveness: European Community Respiratory Health Survey II. Thorax. 2007; 62(5):403-410. doi:10.1136/thx.2006.068205
34. Mahler DA. Is physical activity anti-inflammatory on the airways? Thorax 2007; 62(5): 376 doi: 10.1136/thx.2006.074021