Mannitol as a challenge test to identify exercise-induced bronchoconstriction in elite athletes

Bronchial provocation tests provide objective criteria for asthma and exercise-induced bronchoconstriction (EIB) and were recommended to justify the use of inhaled beta2-agonists by athletes at the Winter Olympics 2002. Eucapnic voluntary hyperpnea (EVH) was one test recommended to identify EIB. Provocation with EVH requires a special dry gas mixture limiting its availability. Provocation tests with osmotic aerosols require less expensive equipment that is easily portable. We assessed the sensitivity of a challenge with mannitol to identify responsiveness to EVH in 50 elite summer sport athletes who were unselected if they had respiratory symptoms. Asthma was previously diagnosed by a doctor in 27 subjects, and 21 subjects were currently under treatment for EIB or asthma. The mean predicted FEV1 was 103.6 +/- 10.8%, FVC was 99 +/- 13.3%, and mean forced expiratory flow during the middle half of the FVC was 104 +/- 22.7%. A total of 25 subjects were positive to EVH challenge (mean percentage of fall in FEV1 was 25.4 +/- 15% SD), and 26 subjects had a positive mannitol challenge (geometric mean [95% confidence interval] provoking dose causing a 10% fall in forced expiratory volume in one second [PD10] was 202 mg [134, 300], with 24 of the subjects positive to both challenges). Mannitol had a sensitivity of 96% and specificity of 92% to identify a positive response to EVH and, as such, could be used as an alternative to EVH to identify EIB.

Recognition and management of exercise-induced bronchospasm

Exercise-induced bronchospasm is an obstruction of transient airflow that usually occurs five to 15 minutes after physical exertion. Although this condition is highly preventable, it is still underrecognized and affects aerobic fitness and quality of life. Diagnosis is based on the results of a detailed history, including assessment of asthma triggers, symptoms suggestive of exercise-induced bronchoconstriction, and a normal forced expiratory volume at one second at rest. A trial of therapy with an inhaled beta agonist may be instituted, with the subsequent addition of inhaled anti-inflammatory agents or ipratropium bromide. Nonpharmacologic measures, such as increased physical conditioning, warm-up exercises, and covering the mouth and nose, should be instituted. If symptoms persist, pulmonary function testing is warranted to rule out underlying lung disease.

Inspiratory stridor in elite athletes

STUDY OBJECTIVES

Diagnosis and medical intervention for exercise-induced bronchospasm (EIB) are often based on self-reported symptoms, without spirometric confirmation. Inspiratory stridor (IS), a symptom of vocal cord dysfunction (VCD), is frequently mistaken for EIB wheeze. Athletes with exercise IS that spontaneously resolves on activity cessation are suspect for VCD and may not have EIB. This study estimated IS prevalence in elite athletes and determined its relationship to EIB.

SUBJECTS/METHODS

Three hundred seventy athletes (174 female and 196 male subjects) provided a medical history, and underwent spirometry before and after exercise challenge. Exercise challenges were conducted in cold, dry ambient conditions. EIB positive (EIB +) was defined as a > or = 10% postexercise fall in FEV(1). Athletes were monitored for IS during exercise; 78.4% of the athletes in this study (n = 290) were tested on multiple occasions.

RESULTS

EIB was identified in 30% of 370 athletes tested (58 female and 53 male subjects). IS was observed in 5.1% (18 female and 1 male subjects) during exercise and spontaneously resolved in these subjects within 5 min after exercise cessation. Ten IS-positive (IS +) athletes (52.6%) were EIB +, and 8 of these athletes had a previous EIB diagnosis; however, beta(2)-agonist treatment resolved IS in only 2 subjects. Eight of nine IS +/EIB-negative (EIB -) athletes had a previous EIB diagnosis; seven subjects received beta(2)-agonist treatment with no IS resolution. Resting spirometric measurements did not distinguish IS, but postexercise mid-flow (FEF(50)/FIF(50)) ratio > 1.5 was more frequent (33%, p < 0.05) among IS + athletes. The FEF(50)/FIF(50) ratio was higher for IS +/EIB + athletes than for IS -/EIB + athletes (1.97 +/- 1.69 vs 0.81 +/- 0.39, p < 0.05). The postexercise fall in FVC was greater (p < 0.05) for IS +/EIB - athletes (9.2 +/- 5.0%) than for IS-negative (IS -) /EIB - athletes (5.3 +/- 4.3%). No difference in postexercise FEV(1) was identified between IS + and IS - athletes (within EIB + or EIB - groups).

CONCLUSIONS

Five percent of athletes were IS +, with EIB comorbidity observed in 53% of these subjects. Misdiagnosis of IS as EIB is common. The lack of a beta(2)-agonist response in combination with postexercise serial spirometry can be useful in excluding solitary IS and confirming EIB diagnosis.

Is asthma over- or under-diagnosed in athletes?

A high prevalence of asthma has been reported in athletes. However, studies in this population usually show an even higher prevalence of airway hyperresponsiveness (AHR) and exercise-induced bronchoconstriction (EIB). This report compares studies on self-reported or physician-diagnosed asthma in athletes with those using objective measures of airflow limitation or airway responsiveness. The higher prevalence of AHR (or EIB) measured in athletes, when compared with the prevalence of self-reported or physician-diagnosed asthma, suggests that abnormal airway responses are common in athletes, although they are infrequently associated with troublesome respiratory symptoms. This may indicate underdiagnosis of asthma in athletes, possibly due to an underreporting of respiratory symptoms or a reduction in perception of nociceptive sensations with repeated exercise over time, or it may simply mean that high-level training is associated with asymptomatic AHR. In athletes, as in the general population, the use of subjective methods such as surveys and questionnaires results in an underestimation ofthe prevalence of airway dysfunction when compared with objective measurements. The significance of these observations is unknown, and there is a need to determine their long-term consequences for athletes.

[Exercise-induced asthma]

Physical exercise and, in particular, sport activities put strain on the respiratory system due to increased. Though healthy subjects undergo a light distension of the respiratory passages, those with bronchial hyperreactivity experience a decrease of lung function. The main triggers responsible are the relative cooling down, drying up and--compared to healthy subjects--overfast airway rewarming. Though, for this reason, basically every asthma patient can expect to suffer the effects of exercise-induced asthma, the solution is not in overprotection and the avoidance of all physical effort. Thanks to dosed, physical activity training programs, any asthmatic can be included in school sports or, as an adult, take part in sports and leisure activities, even at an above-average level.

Vocal cord dysfunction induced by methacholine challenge testing

STUDY OBJECTIVES

To determine whether methacholine challenge testing (MCT) provokes vocal cord dysfunction (VCD), as evidenced by inspiratory vocal cord closure on direct laryngoscopy, and whether spirometry and flow-volume loops (FVLs) demonstrate any changes that are suggestive of VCD.

DESIGN

Prospective, controlled study.

SETTING

Army medical center.

PATIENTS

Thirty-four subjects all with normal baseline spirometry. Ten subjects had documented evidence of VCD, 12 subjects had exercise-induced asthma (EIA) and reactive MCT, and 12 subjects served as healthy asymptomatic control subjects.

METHODS

Measurement of spirometry with FVLs and direct laryngoscopy of the vocal cords performed immediately before and after subjects had undergone MCT.

RESULTS

Evidence of inspiratory vocal cord adduction was found in four VCD patients. Two patients had adducted vocal cords at baseline, and their conditions were unchanged after undergoing MCT. Two other patients had normal conditions at baseline and demonstrated acute inspiratory vocal cord adduction after undergoing MCT. None of the patients in the EIA or control groups had evidence of VCD at baseline or after undergoing MCT. Truncation of the inspiratory limb of the FVL after MCT was noted in five patients, which correlated with evidence of VCD in 60% of these patients. One EIA patient had truncation of the inspiratory FVL after MCT, and no changes were found in the control group. A comparison of spirometry between EIA patients and VCD patients with and without evidence of inspiratory vocal cord adduction during MCT showed no significant differences.

CONCLUSIONS

The findings suggest that MCT may cause an acute episode of vocal cord adduction and that positive results may not reflect underlying reactive airways disease. However, a flattening or truncation of the inspiratory FVL after the patient undergoes MCT is not diagnostic for the presence of inspiratory vocal cord adduction.

[Prevalence of exercise-induced asthma in school children]

BACKGROUND

Although asthma is the most common pulmonary condition in pediatrics, the incidence of exercise-induced asthma (EIA) in school children is not well documented and few studies have been devoted to the condition. There are considerable variations in morbidity and mortality between countries. This study was designed to evaluate the prevalence of EIA in children in the 6th grade (11-14 year-olds) in one French department (Haute-Vienne) and to identify undiagnosed cases.

METHODS

The representative sample was obtained over a period of 28 days (February 2(nd) to April 10(th) 1998) by cluster sampling method, stratified by size of the schools. The number of subjects planned was 891. The selected children filled in a questionnaire on their asthma history and were subjected to an outdoor exercise test (6 minute run). Respiratory function was measured with a peak flow-meter.

RESULTS

Seven hundred and eighty two school children were included in this survey. Participation rate was 87.8%. The prevalence of asthma from the questionnaire was 10.7% (CI 95%: 8.7 - 12.8). After exercise, 68 school children presented exercise-induced bronchospasm: the prevalence of the EIA was 8.7% (CI 95%: 6.9 - 10.5). Among these 68 school children, 27 were known asthmatics and 41 were not. With the 10 treated asthmatics, the overall prevalence of EIA was therefore estimated at 9.9% (CI 95%: 8.2 - 11.7).

CONCLUSION

The prevalence of asthma and EIA was close to that found in other studies using a similar methodology. EIA remains under-diagnosed since 41 undeclared asthmatic school children were identified in our population. Nurses'information is necessary to initiate the use of systematically testing respiratory function (with a peak flow meter) at least once a year. Efficient management of the asthmatic child requires cooperation between the various professionals dealing with school children.

Exercise-induced asthma: diagnosis and management

OBJECTIVE

To review the diagnosis and management of exercise-induced asthma (EIA).

DATA SOURCES

Computer-assisted literature searches on MEDLINE for articles, abstracts, and other relevant data on exercise-induced asthma

STUDY SELECTION

Published articles, abstracts, and conference proceedings were selected.

RESULTS

EIA is seen in 40 to 90% of asthmatic patients. Exercise can be the sole trigger or be one of multiple triggers of asthma exacerbations. A good history and physical examination can diagnose most cases of EIA. Spirometry can confirm the diagnosis. Exercise testing may be necessary in certain cases. Prevention through both pharmacologic and nonpharmacologic measures is the key to EIA management. Inhaled beta-agonists remain the medications of choice for EIA prophylaxis. Inhaled cromolyn and antileukotrienes are alternatives. Good long-term control of asthma with anti-inflammatory medications such as inhaled steroids will also decrease the incidence of EIA.

CONCLUSIONS

Early diagnosis and proper preventive and maintenance therapy can reduce episodes of EIA and enable patients to continue to engage in sports and lead an active life.

[Exercise-induced laryngomalacia]

Exercise-induced laryngomalacia is a rare differential diagnosis of exercise-induced asthma. We report the case of a previously fit 14-year-old female patient who presented with dyspnoea on intense exertion and whose condition had not improved with treatment prescribed for a misdiagnosed exercise-induced asthma. A diagnosis of exercise-induced laryngomalacia was eventually made when a variable extra-thoracic airway obstruction on the flow-volume loops was obtained after an incremental exercise test. Flexible fiberoptic rhinolaryngoscopy confirmed this abnormality and demonstrated an anterior prolapse of the arytenoid region, partially obstructing the airway. The patient therefore underwent laser aryepiglottoplasty which produced a satisfactory anatomical outcome in the larynx but which only resulted in a partial functional improvement. Laryngomalacia is rare and its pathophysiology is not well understood. However, it should be considered in patients presenting with exertional dyspnoea, particularly if there is inspiratory embarrassment, who fail to improve with beta-2-adrenergic agonists. The diagnosis can be made from the flow-volume loop and direct laryngoscopy, before and after exercise.

Exercise-induced bronchoconstriction

Exercise-induced asthma, or more appropriately, exercise-induced bronchoconstriction (EIB), occurs in 80 to 90% of individuals with asthma and in approximately 11% of the general population without asthma. EIB is characterised by post-exercise airways obstruction resulting in reductions in forced expiratory volume in 1 second (FEV(1)) of greater than 10% compared with pre-exercise values. The mechanism of EIB remains elusive, although both cooling and drying of airways play prominent roles. Cold, dry inhaled air during exercise or voluntary hyperventilation is the most potent stimulus for EIB. Inflammatory mediators play central roles in causing the post-exercise airways obstruction. Diagnosis of EIB requires the use of an exercise test. The exercise can be a field or laboratory based test, but should be of relatively high intensity (80 to 90% of maximal heart rate) and duration (at least 5 to 8 minutes). Pre- and post-exercise pulmonary function should be compared, and post exercise pulmonary function determined over 20 to 30 minutes for characterisation of EIB. A pre- to post-exercise drop in FEV(1) of greater than 10% is abnormal. Approaches to treatment of EIB include both nonpharmacological and pharmacological strategies. A light exercise warm up prior to moderate to heavy exercise reduces the severity of EIB. More recently, studies have supported a role for dietary salt as a modifier of the severity of EIB, suggesting that salt restrictive diets should reduce symptoms of EIB. Short acting, inhaled beta(2)-agonists constitute the most used prophylactic treatment for EIB. However, antileukotriene agents are emerging as effective, well tolerated, long-term treatments for EIB.

Exercise-induced asthma in children

Exercise-induced asthma (EIA) is a relatively common problem in children, but may not be recognized because children either do not report their symptoms, or avoid activities that cause it. Clarifying the diagnosis of EIA, in particular separating EIA from other causes of exertional dyspnea, is essential. Treating EIA in children is challenging because of the nature of their physical activities, which are often not planned, and may be prolonged. Keeping children active is an important goal to ensure healthy physical and social development. Many children with EIA are well managed with an inhaled short-acting beta(2)-adrenoceptor agonist before exercise or if symptoms develop. The approach to more troublesome EIA depends on whether the child has persistent asthma and requires better prevention, or the EIA is an isolated clinical problem. The options for treatment also depend on the timing, frequency, and duration of activity that induces EIA. Options include the addition of a cromone, a leukotriene modifier, an inhaled corticosteroid, or switching to use a long-acting beta(2)-adrenoceptor agonist. The use of warm-up exercises has been shown to be helpful by using the refractory period but is not practical for most children with EIA. A final consideration for successful management of EIA in children is that the delivery of medication needs to be age-appropriate.

Exercise-induced asthma in children: a marker of airway inflammation

What we know: Exercise-induced asthma (EIA) occurs in up to 23% of schoolchildren. In 40% of children with demonstrable EIA, no clinical diagnosis of asthma has been made. Children with asthma and EIA have eosinophils in their sputum, consistent with active asthma. EIA is well controlled in 50%-65% of children with moderate to severe asthma, so that only a minority will need prophylactic therapy immediately before exercise. Beta(2)-agonists are not the most suitable therapy for preventing EIA if they need to be used on a daily basis. The severity of EIA appears to be an indirect index of the severity of airway inflammation. What we need to know: Do non-symptomatic children with EIA require treatment for asthma? Does failure to identify and treat children unaware of their airways narrowing after exercise lead to airflow limitation in the long term, particularly in the small airways? Can exercise, or surrogate tests used to identify EIA, also be used to assess children with asthma? What is the minimum dose of steroid required to inhibit EIA, as high doses of steroids may be inappropriate in children? What is the best prophylactic treatment for EIA in children whose asthma is otherwise well controlled by inhaled steroids? What is the best prophylactic treatment for EIA in children with frequent episodic asthma or mild persistent asthma? Are leukotriene antagonists alone better than beta(2)-agonists alone in preventing EIA throughout the day? How many children taking long-acting beta(2)-agonists twice daily, either alone or in combination with an inhaled steroid, experience breakthrough EIA during school and require rescue medication?

Racing Alaskan sled dogs as a model of "ski asthma"

Athletes who play sports in cold weather, particularly skaters and cross-country skiers, have an increased prevalence of lower airway disease that is hypothesized to result from repeated penetration of incompletely conditioned air into the lung periphery. In this study, we investigated the hypothesis that canine winter athletes also suffer from increased prevalence of lung disease secondary to hyperpnea with cold air. Bronchoscopy and bronchoalveolar lavage was conducted in elite racing sled dogs 24 to 48 hours after completion of a 1,100-mile endurance race. Bronchoscopic abnormalities were classified as none, mild, moderate, or severe, based on the quantity and distribution of intralumenal debris. Eighty-one percent of the dogs (48 of 59) examined had abnormal accumulations of intralumenal debris, with 46% (27 of 59) classified as moderate or severe, indicating significant accumulation of exudate. Bronchoalveolar lavage obtained from dogs after the race had significantly higher nucleated macrophage and eosinophil counts compared with sedentary control dogs. Our findings support the hypothesis that strenuous exercise in cold environments can lead to lower airway disease and suggest that racing sled dogs may be a useful naturally occurring animal model of the analogous human disease.

Exercise-induced bronchospasm in the elite athlete

The term exercise-induced bronchospasm (EIB) describes the acute transient airway narrowing that occurs during and most often after exercise in 10 to 50% of elite athletes, depending upon the sport examined. Although multiple factors are unquestionably involved in the EIB response, airway drying caused by a high exercise-ventilation rate is primary in most cases. The severity of this reaction reflects the allergic predisposition of the athlete, the water content of the inspired air, the type and concentration of air pollutants inspired, and the intensity (or ventilation rate) of the exercise. The highest prevalence of EIB is seen in winter-sport populations, where athletes are chronically exposed to cold dry air and/or environmental pollutants found in indoor ice arenas. When airway surface liquid lost during the natural warming and humidification process of respiration is not replenished at a rate equal to the loss, the ensuing osmolarity change stimulates the release of inflammatory mediators and results in bronchospasm; this cascade of events is exacerbated by airway inflammation and airway remodelling. The acute EIB response is characterised by airway smooth muscle contraction, membrane swelling, and/or mucus plug formation. Evidence suggests that histamine, leukotrienes and prostanoids are likely mediators for this response. Although the presence of symptoms and a basic physical examination are marginally effective, objective measures of lung function should be used for accurate and reliable diagnosis of EIB. Diagnosis should include baseline spirometry, followed by an appropriate bronchial provocation test. To date, the best test to confirm EIB may simply be standard pulmonary function testing before and after high-intensity dry air exercise. A 10% post-challenge fall in forced expiratory volume in 1 second is used as diagnostic criteria. The goal of medical intervention is to limit EIB exacerbation and allow the athlete to train and compete symptom free. This is attempted through daily controller medications such as inhaled corticosteroids or by the prophylactic use of medications before exercise. In many cases, EIB is difficult to control. These and other data suggest that EIB in the elite athlete is in contrast with classic asthma.

Value of a negative aeroallergen skin-prick test result in the diagnosis of asthma in young adults: correlative study with methacholine challenge testing

BACKGROUND

None of the existing tests for the diagnosis of asthma are considered to be definitive. Certain circumstances require prompt diagnosis, and a test able to predict the absence of asthma would be very useful.

OBJECTIVE

To evaluate the contribution of a skin-prick test (SPT) to the diagnostic workup of subjects with suspected asthma.

PATIENTS AND METHODS

The study included three groups of subjects aged 18 to 24 years: group A, asthmatic patients (n = 175); group B, control subjects (n = 100); and group C, subjects with suspected asthma (n = 150) with normal spirometry findings and a negative exercise challenge test result. All underwent an SPT to a battery of common aeroallergens, and group C underwent a methacholine challenge test (MCT) in addition. The sensitivity, specificity, positive predictive value, and negative predictive values (NPV) of the SPT were calculated using provocative concentrations of methacholine causing a 20% fall in FEV(1) (PC(20)) of < 4 mg/mL and < 8 mg/mL as diagnostic cutoff values for asthma in the MCT. Bayes' formula was used to determine posttest probabilities of having asthma, both for positive and negative SPT results.

RESULTS

A positive SPT result to at least one allergen was found in 95.5%, 54%, and 69% of patients in the three groups, respectively. The sensitivity, specificity, and NPV of the SPT were 90.7%, 52.0%, and 84.8%, respectively, with a cutoff value of PC(20) < 8 mg/mL. The lower cutoff, PC(20) < 4 mg/mL, increased the sensitivity and NPV to 98.2% and 97.8%, respectively. A negative SPT result decreased the probability of having asthma by 10-fold to 20-fold in subjects whose pretest probability was low to moderate.

CONCLUSIONS

Incorporating an SPT into the workup of subjects with suspected asthma can reduce the cost of this process significantly. The SPT may be used as a simple, fast, safe, inexpensive, and reliable method to predict the absence of asthma in young adults.

Exercise in elite summer athletes: Challenges for diagnosis

BACKGROUND

There is a high prevalence of asthma and exercise-induced bronchoconstriction (EIB) in elite athletes when the diagnosis is based on symptoms and medication use. Objective measurements are now required by some sporting bodies to support a diagnosis of asthma or EIB to justify use of beta-agonists. Such measurements could include bronchial provocation with methacholine, with eucapnic voluntary hyperpnea (EVH) of dry air (a surrogate for exercise), or both.

OBJECTIVE

The aim of the study was to investigate the relationship between asthma symptoms and responses to methacholine and the EVH challenge in a group of unselected elite summer-sport athletes. The outcome would be to inform practitioners of a suitable objective approach to identifying those with asthma and EIB.

METHODS

Fifty elite summer-sport athletes with or without asthma were recruited from sporting teams and sports medicine centers throughout Melbourne, Australia. All subjects completed a respiratory questionnaire and, on separate days, underwent a bronchoprovocation challenge test with methacholine and EVH.

RESULTS

Forty-two subjects reported one or more respiratory symptoms in the past year, 9 had positive methacholine challenge results (mean PD(20) of 1.69 +/- 2.05 micromol), and 25 had positive EVH challenge results (mean fall in FEV(1) of 25.4% +/- 15%). Although all subjects with positive methacholine challenge results had positive EVH challenge results, methacholine had a negative predictive value of only 61% and a sensitivity of 36% for identifying those responsive to EVH.

CONCLUSION

These findings suggest that the pathogenesis of EIB in elite athletes might be different from that of asthma, and as such, neither symptoms nor the methacholine challenge test should be used exclusively for identifying EIB.

A sport-specific protocol for diagnosing exercise-induced asthma in cross-country skiers

OBJECTIVE

This study evaluates a sport-specific protocol to evaluate cross-country skiers for exercise-induced asthma (EIA).

STUDY DESIGN

Participants completed an asthma symptom questionnaire prior to participation. They were then tested by portable digital spirometer with measurements prior to exercise and at 5-minute increments following a 15-minute cross-country skiing exercise session on a groomed ski trail.

SETTING

All spirometry measurements were collected indoors at Nordic ski areas in the Duluth, Minnesota, area. Each ski area was groomed for both skating and classical technique.

SUBJECTS

99 high school skiers, 55 female and 44 male, of various skill levels were tested. All were members of their respective high school cross-country ski team. Testing was open to all ski team members. Skiers from seven different high schools participated.

MAIN OUTCOME MEASURES

Bronchial hyperresponsiveness to exercise measured by the change in forced expiratory volume at 1 s (FEV1) following exercise. A result was considered positive if the decrement in FEV1 was greater than 10% in any two of the postexercise test increments in comparison with the preexercise baseline.

RESULTS

28 of 99 (28%) skiers met the criteria for EIA. No significant differences were found with regards to gender, age, or previous experience. Several individual items on the Asthma Symptom Questionnaire were associated with a positive spirometry test.

CONCLUSIONS

Using a simple protocol of pre- and postexercise spirometry with a defined exercise challenge, a large number of athletes were screened objectively for this condition. Both the equipment and protocol worked well in the field environment and could easily be adapted to most any sports environment.

[Asthma and exercise]

Exercise-induced asthma (EIA) is defined as the clinical occurrence of shortness of breath, cough or wheeze that occurs typically 5-15 minutes after the cessation of the exercise. In most patients with EIA, bronchoconstriction is followed by a refractory period, during which repeated exertion causes less bronchoconstriction. The occurrence of this type of asthma is influenced by the intensity and the duration of exercise. It is now generally believed that EIA affects all patients with asthma if challenged with exercise of sufficient intensity. The estimate prevalence varies from 7 to 15% in the general population. EIA appears also to affect 3-14% of athletes. It is now clear that hyperventilation and hypertonicity of airway-lining fluid provide the stimulus for EIA with release of constrictor mediators. Recently, incidence of new diagnoses of asthma is associated with heavy exercise in communities with high concentrations of ozone, thus, air pollution and outdoor exercise could contribute to the development of asthma in children. Beta-agonists and/or disodium cromoglycate remain the preferred first-line therapy for EIA but now antileukotrienes provide an attractive therapeutic alternative. General recommendations can help reduce its severity: warm-up; breath through mask when exercising in cold, dry conditions; in recent years some reports have suggested that training and conditioning may help athletes and non-athletes with asthma have fewer symptoms after exercise, increase the threshold of exercise necessary to induce airway obstruction and finally improve their well-being. Scuba diving stays an absolute contra-indication if asthma.

Pulmonary problems and management concerns in youth sports

In the overwhelming majority of exercising youngsters, exercise tolerance is limited by cardiovascular and muscular factors, not the lungs. Even at exhaustion, pulmonary reserve is considerable. Yet some young athletes do experience respiratory problems with exercise. These problems can be assigned to several categories, including those related to underlying acute and chronic respiratory conditions (principally respiratory tract infections, asthma, cystic fibrosis, chest wall deformities, and neuromuscular disorders), and apparent but nonpathological problems (the heavy breathing of anaerobic exercise, relative deconditioning, and anxiety). There are also situations that seem to be problematic but need not be (having the diagnosis of asthma or cystic fibrosis). Pharmacologic management of respiratory problems and perceived problems can be difficult and is discussed with the particular disorder.

Exercise-induced asthma among Thai asthmatic children

BACKGROUND

Approximately seventy per cent of asthmatic children from temperate climates, with normal lung function, have exercise-induced asthma (EIA). There is certain evidence to suggest that EIA may be less frequently encountered among children who live in tropical climates. Prevalence of EIA in Asian asthmatic children has never been thoroughly studied.

OBJECTIVE

To study the prevalence of EIA among Thai asthmatic children.

METHOD

A prospective study was performed to determine the prevalence of EIA in 44 Thai asthmatic children who were able to perform the spirometric maneuver. Subjects were randomly selected asthmatic children from the Pediatric Allergy Clinic, Department of Pediatrics, Siriraj Hospital. They were subjected to exercise testing on a steady state, motor-driven treadmill for 6 minutes (mean speed +/- SD = 3.7 +/- 0.4 km/h, mean level of inclination + SD = 15.0 +/- 5.2 degrees). The testing was conducted in a temperature-controlled (mean temperature +/- SD = 24.4 +/- 0.8 degrees C) and humidity-controlled environment (mean relative humidity +/- SD = 41.7 +/- 2.1%). Lung function tests were performed before exercise, immediately after and at 3, 5, 10, 15, 20 and 30 minutes after exercise. Results of the lung function test were calculated as per cent falls of forced expiratory volume in 1 sec (FEV1), peak expiratory flow rate (PEFR), and forced expiratory flow at 25 per cent-75 per cent (FEF50) from baselines. EIAs were diagnosed when drops of FEV1, PEFR and FEF50 were greater than 20 per cent, 25 per cent and 25 per cent from baseline values, respectively.

RESULTS

Of the 44 patients studied (31 boys and 13 girls; mean age 11.9 years), 34 per cent had mild asthma. Fifty-nine per cent had moderate asthma and 7 per cent had severe asthma. Eleven patients (25%) had EIA diagnosed by significant falls of FEV1's (26 +/- 12.6%), whereas, 13 patients (30%) and 20 patients (45%) had EIA defined by significant drops of PEFR's and FEF50's, respectively. A total of 23 patients (52%) had EIA by one or more diagnostic criteria. Peak times for EIA as diagnosed by FEV1, PEFR and FEF50 occurred at 3, 10, and 10 minutes respectively, after exercise. Most EIA episodes observed were of mild degree.

CONCLUSIONS

The prevalence of EIA in Thai children is much lower than figures reported in studies from Western countries. By using a significant fall of FEV1's as the diagnostic criteria, only 25 per cent were diagnosed as having EIA. By PEFR and FEF50 criteria, percentages of EIA increased to 30 per cent and 45 per cent respectively. Screening for EIA, therefore, may not be an appropriate diagnostic tool for the diagnosis of childhood asthma in tropical climates.

Exercise-induced asthma

Exercise-induced asthma (EIA) is common in asthmatic children and adolescents. Since it may cause limitations to daily life activities in up to 30%, mastering EIA is important in asthma management. EIA consists of bronchial obstruction occurring immediately, or soon after, physical exercise as a result of increased respiratory water and heat loss due to increased ventilation during exercise, with the subsequent release of mediators and stimulation of airways receptors. Diagnosis is best made by standardised exercise tests, preferably running on a treadmill for 6-8 minutes at an exercise load of 95% of maximum. The sensitivity of the test may be increased by cold air inhalation. EIA is best treated by inhaled steroids in addition to pre-treatment before exercise by inhaled beta(2)-agonists, short or long acting, and/or leukotriene antagonists. Physical training may improve physical fitness and quality of life in asthmatic children but baseline lung function and bronchial responsiveness are not improved.

A study of the association between exercise-induced wheeze and exercise versus methacholine-induced bronchoconstriction in adolescents

Among asthmatics, exercise-induced wheeze (EIW) is a frequent symptom, and 40-77% of asthmatics demonstrate exercise-induced bronchoconstriction (EIB). In the North-Trøndelag population-based survey of 8,571 adolescents (YOUNG-HUNT), 26% reported wheeze during the previous 12 months (current wheeze). Of those subjects, 50% reported EIW. The aim of the present study was to investigate the association between EIW and EIB in randomly selected adolescents with EIW as the only or predominant asthma-like symptom, and to relate our findings to results from methacholine bronchoprovocation tests (MT) and measurements of exhaled nitric oxide (ENO). Sixty-three subjects with current wheeze induced by exercise, but not by allergen exposure, were investigated using a treadmill exercise test (ET) and measurements of ENO. Fifty-eight subjects completed a MT on a separate study day. EIB was defined as a fall of >or= 10% in the forced expiratory volume in 1 second (FEV1) after exercise (DeltaFEV1%ex). Twenty-one subjects (33%) had EIB and 33 (57%) had a positive MT. The degree of reported dyspnea during the ET was not correlated to the DeltaFEV1%ex. The correlation between EIB and methacholine-induced bronchoconstriction (MIB) was poor, and the DeltaFEV1%ex was more pronounced in smokers than in non-smokers. Moreover, ENO was not increased in subjects with positive vs. negative ET. Hence, EIW, when reported as the only or predominant asthma-like symptom, was linked to EIB in only one-third of the patients. We conclude that EIW is a poor predictor of EIB in epidemiological studies. The poor correlation between EIB and MIB indicates that these two tests measure different mechanisms of bronchial hyper-responsiveness.

Asthma screening of high school athletes: identifying the undiagnosed and poorly controlled

BACKGROUND

It is believed that there are many high school-age athletes who have undiagnosed asthma or exercise-induced asthma (EIA). The screening of these athletes for EIA will allow them to be identified and treated.

OBJECTIVES

1) To obtain reliable peak expiratory flow rate (PEFR) measurements and administer questionnaires to high school-age athletes to evaluate their asthma risk. 2) To identify high-risk athletes for having EIA or asthma by a free run challenge test. 3) To evaluate whether an athlete's present asthma control is adequate. 4) To evaluate these tools for their value as screening tools for asthma or EIA.

METHODS

Eight hundred one student athletes from 10 suburban Pittsburgh schools were screened for more than 18 months for asthma as part of their preparticipation sports physicals. The screening included all athletes from all high school sports. The athletes were given a brief questionnaire, had PEFR measured, and then participated in a free running exercise challenge.

RESULTS

Forty-six of 801 athletes had asthma or EIA, Of the remaining 755 athletes, 49 athletes were identified as having undiagnosed asthma. In the previously unrecognized athletes with EIA, the positive and negative predictive value of the questionnaire was 42% and 97%, respectively. Eighty-five percent (39 of 46) of the known asthmatic athletes, using their recommended medication, failed their free running test by a >15% drop of their PEFR.

CONCLUSIONS

The free running test is a good test for identifying and assessing the athlete with EIA. The PEFR meter is not a good screening tool for EIA in the high school athlete. A questionnaire may be a good negative screening tool, but further development is needed before it can be used for widespread screening.

Evidence-based management of exercise-induced asthma

Exercise-induced asthma (EIA) is a common, yet often unrecognized condition occurring in both known asthmatics and otherwise healthy individuals. Misdiagnosis, both over- and underdiagnosis, is not uncommon. In order to accurately diagnose EIA, a bronchoprovocation challenge test must be performed; the current recommended test is a eucapnic hyperventilation (EVH) challenge test. Although there are a number of treatment options available, both pharmacologic and nonpharmacologic, in most cases medications are required. A range of medications are currently available to either treat or prevent EIA. It is important that the medications used are individualized to the patients needs and monitored to ensure efficacy.

Atopy may be related to exercise-induced bronchospasm in asthma

BACKGROUND

Recent studies suggest that atopy may be associated with exercise-induced bronchospasm (EIB) in asthma. However, it is not clear whether atopy is related to EIB, regardless of airway hyper-responsiveness (AHR) to methacholine, because asthmatic subjects often show AHR to exercise and methacholine simultaneously.

OBJECTIVE

To investigate whether atopy is related to EIB in asthmatic subjects, independently of AHR to methacholine.

METHODS

Fifty-eight male asthmatic subjects were studied. Initial spirometry was performed. Skin prick test was carried out, using 53 common allergens including mites dust antigen. Atopy score was defined as a sum of mean weal diameters to all allergens tested. Methacholine bronchial provocation testing was performed. Twenty-four hours later, free running test was performed. Positive EIB was defined as a 15% reduction or more in FEV1 from baseline after exercise.

RESULTS

All subjects had AHR to methacholine. The degree of AHR to methacholine in asthmatics with EIB was similar to that in asthmatics without EIB. However, atopy score and skin reaction to Dermatophagoides pteronyssinus significantly increased in asthmatics with EIB compared with those without EIB (P < 0.05, respectively). Furthermore, the degree of EIB significantly correlated with atopy score in all subjects (r = 0.35, P < 0.01). This relationship was maintained even after the exclusion of EIB-negative asthmatic subjects.

CONCLUSION

Atopy defined as skin test reactivity may contribute to the development of EIB in asthma, independently of AHR to methacholine.

Seasonal difference in the occurrence of exercise-induced bronchospasm in asthmatics: dependence on humidity

BACKGROUND

Most studies on the effects of temperature and humidity on exercise-induced bronchospasm (EIB) in asthmatics have been carried out under indoor conditions. However, any asthmatic patient is exposed to varying climatic conditions.

OBJECTIVE

To investigate whether temperature or relative humidity plays a more important role in determining the degree of EIB in asthmatics under naturally exposed climate conditions.

METHODS

To exclude the effects of pollen on EIB, we enrolled 69 subjects with perennial asthma (mean +/- SD: 20.1 +/- 1.5 years). The subjects performed outdoor free running tests. They were divided into winter (n = 25), spring/autumn (n = 22), and summer (n = 22) groups according to the season when they performed the tests. Initial spirometry and skin prick tests were performed. Methacholine bronchial challenge testing and, one day later, the free running tests were done.

RESULTS

There were significant differences in temperature and relative humidity among the three groups: However, the relative humidity in winter did not differ from that in spring/autumn. There were no differences in pulmonary functions, airway responsiveness, and atopy score among the three groups. The percentage of cases of positive EIB --fall in forced expiratory volume in 1s FEV(1) of >15% from baseline --in winter (84%, p < 0.05) or spring/autumn (86.4%, p < 0.05) was higher than that in summer (50%). However, the percentage of subjects with a positive EIB in winter did not differ from that in spring/autumn. The maximal percent fall in FEV(1) after exercise in winter did not differ from that in spring/autumn.

CONCLUSIONS

The occurrence of EIB is associated with environmental temperature and humidity. Under such climatic conditions as in Korea, relative humidity may be a more important factor than temperature in contributing to EIB in patients with perennial asthma.

Defining asthma in the preschool-aged child

A physician faces many challenges in making a definitive diagnosis of asthma in young children. Although there are clinical and historical features consistent with asthma, identical features are present in many other diseases. Furthermore, there is no specific test for asthma. Other diseases must always be ruled out before a definitive diagnosis of asthma is made. Determining whether cough or wheeze is the primary symptom is important because asthma is primarily a wheezing disease. Sweat chloride testing, chest radiography, and allergy skin testing should be performed in children with persistent wheezing to rule out other causes and help support a diagnosis of asthma. Allergy skin testing provides particularly useful information for making a diagnosis of asthma in the preschool-aged child. A chart review of patients presenting consecutively to the Division of Allergy and Pulmonary Medicine provides insight and information on an approach to make an asthma diagnosis for this population.

[Prevalence of respiratory symptoms and clinical conditions and associated asthma in schoolchildren in Rio de Janeiro, Brazil]

OBJECTIVE

We compared the prevalence of respiratory symptoms and clinical conditions associated to bronchial asthma and exercise-induced bronchospasm (EIB) in schoolchildren from public and private schools.

METHODS

We conducted a cross-sectional questionnaire (ATS-DLD-78 C modified) survey in 2941 children 6-14 years of age attending public (n = 1951) and private (n = 1350) elementary and secondary schools in Rio de Janeiro.

RESULTS

Wheezing was found in 842 (28.6%) students; 684 students (23.3%) showed symptoms of EIB; 342 (11.6%) children related hospitalization owing to respiratory problems; previous use of bronchodilators (BD) was reported by 1072 (36.5%) children; bronchiolitis, pneumonia and rhinitis were observed in respectively 40 (1.4%), 185 (6.3%) and 1088 (37%) children. Family history of atopy and immunotherapy were related by 1794 (61%) and 577 (19.6%) students, respectively. Asthma diagnosed by a physician was observed in 779 (26.5%) children. Using questionnaire criteria we found 638 (21.7%) children with asthma; 354 in public and 284 in private schools. Data statistical analysis showed a higher frequency of EIB, hospitalization and pneumonia in students attending public schools (26.3%, 15.9% and 7.2%, respectively). Children in private schools showed a higher frequency of family history of atopy and immunotherapy (63.7% and 23.6%, respectively).

CONCLUSIONS

We found a high prevalence of asthma among students of public and private elementary and secondary schools in Rio de Janeiro, without statistical differences between the two groups of children. Episodes of EIB were also highly prevalent in this study, with a higher frequency among students of public schools.

Exhaled nitric oxide decreases during exercise-induced bronchoconstriction in children with asthma

Nitric oxide (NO) produced in the airways can be either detrimental or protective to the host. To investigate the role of NO in the pathogenesis of exercise-induced bronchoconstriction (EIB), we measured exhaled NO (ENO) after exercise challenge in 39 asthmatic and six normal children. FEV(1) and ENO were measured before and at 0, 5, 10, and 15 min after exercise performed on a treadmill for 6 min. EIB was defined as a decrease in FEV(1) of more than 15% after the exercise. Normal children (control group) did not have EIB. Twenty-one patients with asthma had EIB (EIB group) whereas the remaining 18 patients did not (non-EIB group). The baseline ENO value was significantly higher in the asthmatic children than in the normal children, and there was a positive correlation between the maximal percent decrease in FEV(1) and the baseline ENO value (r = 0.501, p = 0.012). At the end of the exercise, ENO had decreased in all the subjects. In the non-EIB and control groups, ENO rebounded to above the baseline at 5 min after the exercise and thereafter. In contrast, ENO remained at a decreased level in the EIB group. The change in ENO did not correlate with the change in minute ventilation, and beta-agonist inhalation at the peak of EIB that accelerated the recovery of FEV(1) did not affect the depressed level of ENO, demonstrating that the reduction of ENO is not a simple consequence of increased ventilation nor airway obstruction. Among the EIB group, steroid-treated patients showed sooner recovery in ENO after the exercise than steroid-naive patients. Our study suggests that NO production in response to exercise may be impaired in patients with EIB, and that ENO represents not only airway inflammation but also a protective function of NO in EIB.

A treatment for vocal cord dysfunction in female athletes: an outcome study

OBJECTIVES

This article reports the outcome of a speech pathology treatment program for vocal cord dysfunction (VCD) in 20 adolescent female athletes.

STUDY DESIGN

A retrospective, nonrandomized group design was used to collect the outcome data.

METHODS

Twenty consecutive referrals of female athletes diagnosed as having symptoms of VCD during exercise were assessed, treated, and followed for at least 6 months after treatment.

RESULTS

Ninety-five percent of the participants reported the ability to control symptoms of VCD during exercise up to 6 months after treatment. Asthma medications were no longer used by 80% of the athletes. All of the females continued to participate in athletics.

CONCLUSION

Speech pathology intervention focusing on respiratory control of VCD in adolescent female athletes is an effective treatment resulting in the athletes' ability to control the symptoms of VCD in exercise for at least 6 months after treatment.

Provocation by eucapnic voluntary hyperpnoea to identify exercise induced bronchoconstriction

The International Olympic Committee Medical Commission (IOC-MC) requires notification for use of a beta(2) agonist at the Winter Olympic Games in Salt Lake City. This notification will be required seven days before the event and must be accompanied by objective evidence that justifies the need to use one. The IOC-MC has expressed the viewpoint that, at present, eucapnic voluntary hyperpnoea (EVH) is the optimal laboratory challenge to confirm that an athlete has exercise induced bronchoconstriction (EIB). The EVH test recommended was specifically designed to identify EIB. EVH has been performed in thousands of subjects in both the laboratory and the field. The test requires the subject to hyperventilate dry air containing 5% carbon dioxide at room temperature for six minutes at a target ventilation of 30 times the subject's forced expiratory volume in one second (FEV(1)). The test conditions can be modified to simulate the conditions that give the athlete their symptoms with exercise. A reduction in FEV(1) of 10% or more of the value before the test is considered positive.

Exercise-induced asthma: an overview

Asthmatic attack in exercise-induced asthma is brought about by hyperventilation (not necessarily to exercise), cold air, and low humidity of the air breathed. The effects are an increase in airway resistance, damage to bronchial mucosa, and an increase in bronchovascular permeability. The mechanism of these changes is the release of mediators such as histamine, leukotrienes, nitric oxide, sensory neuropeptides, the inhibition of neuronal activity, and bronchovascular permeability. The cause of asthma and exercise-induced asthma is unknown. It is probably an abnormality of vascular control in the peribronchium and/or an alteration in local adrenergic function. The importance of exercise-induced asthma definition and the use of stimulants in sport and antidoping in sport are discussed.

[Pathogenesis of exercise induced asthma]

Exercise induced asthma is an exaggerated airway response to airway dehydration and the following mediators release from the inflammatory cells. The airway narrowing is primarily caused by bronchial smooth muscle contraction, but in milder form mucus production, airway edema and cough can be observed. In this study we have described some previously and currently proposed hypotheses which may explain pathomechanism of this form of bronchial hyperreactivity.

[Exercise-induced asthma, a complex pathology. New answers, new questions]

This is a short review for general practitioners about the clinical features of exercise induced asthma (EIA), sometimes unusual in presentation, chiefly among children. Some most currently accepted theories explaining the disease are recalled. The ambiguous relationship between asthma and exercise is pointed out: Exercise is a major comportent of asthma treatment but asthma seems more and more a prominent complication of high level sport practice in some disciplines. The need for a clear international definition of EIA is outlined as bronchial hyperactivity alone does not seem a clear-cut criterion for asthma in the general population as well as in athletes. Some useful drugs for the control of EIA are mentioned. A final question: EIA an under- or overdiagnosed disease?

Preventing and managing exercise-induced asthma

Managing exercise-induced asthma is a challenge for the patient and the clinician. As the incidence of exercise-induced asthma increases, health care providers need effective protocols to diagnose and treat these patients in outpatient settings. This article discusses the incidence, risk factors, pathophysiology, diagnosis, and treatment of exercise-induced asthma. Both traditional and new methods of disease diagnosis and treatment in the outpatient setting are explored.

Exercise-induced laryngochalasia: an imitator of exercise-induced bronchospasm

BACKGROUND

Patients with exercise-induced laryngochalasia present with dyspnea and stridor during exercise. Symptoms are due to a subtotal occlusion of the larynx resulting from mucosal edema from the aryepiglottic folds being drawn into the endolarynx.

METHODS

We report on three patients with exercise-induced bronchospasm, refractory to standard therapy.

RESULTS

Spirometry with flow-volume loops revealed truncation of the inspiratory limb. Abnormal movement of the arytenoid region was visualized on laryngoscopy. A diagnosis of exercise-induced laryngochalasia was made.

CONCLUSIONS

Evaluation of laryngeal motion in patients with refractory exercise-induced bronchospasm is important. Surgical correction with laser laryngoplasty is effective in carefully selected cases.

[Dysfunction of the vocal cords simulating exercise-induced asthma]

Vocal cord dysfunction is a respiratory condition characterized by anomalous adduction of the vocal cords during inspiration, causing significant air flow limitation in the larynx. Few such cases have been described in which dysfunction is triggered by exercise. We report the case of a young women with severe dyspnea appearing as a result of physical activity. We first deal with issues of differential diagnosis in relation to several other diseases, particularly exercise-induced asthma and then discuss therapeutic approaches.

Exercise-induced asthma: is it the right diagnosis in elite athletes?

Exercise-induced asthma, as recognized in asthmatic subjects, is an exaggerated airway response to airway dehydration in the presence of inflammatory cells and their mediators. The airway narrowing is primarily caused by contraction of bronchial smooth muscle. The milder airway narrowing documented in response to exercise in elite athletes and otherwise healthy subjects may simply be the result of the physiologic responses and pathologic changes in airway cells arising from dehydration injury. These changes, which include excessive mucus production and airway edema, would serve both to cause cough and to amplify the narrowing effects of normal bronchial smooth muscle contraction, resulting in symptoms. These changes are more likely to occur in healthy subjects who exercise intensely for long periods of time breathing cold air, dry air, or both. Under these conditions, the ability to humidify inspired air may be overwhelmed, causing significant dehydration of the airway mucosa and an increase in osmolarity, even in small airways. In addition to dehydration injury, airway narrowing to pharmacologic and physical agents may occur as a result of injury caused by large volumes of air containing irritant gases, particulate matter, or allergens being inspired during exercise. As a result, the airways may become inflamed, and the airway smooth muscle may become more sensitive. These events could result in the same exaggerated airway response to dehydration, as documented in asthmatic subjects.

[Exercise-induced bronchospasm and its prevention]

Exercise-induced bronchospasm (EIB) is a type of nonspecific bronchial hyperreactivity. It affects mostly children and younger adults with asthma (75%-95%) and allergic rhinitis (40%), but it is also found in 3-11% of the nonasthmatic and nonatopic younger population. Pathophysiology of this phenomenon is not clear and there are some attempts to explain it with hyperosmolality of bronchial epithelia, exchange of heat and water (reactive hyperemia) in airways and reflex vagal bronchospasm. Unrecognized and uncontrolled symptoms of EIB can lead patients to avoid general and occupational physical activities and sports. Diagnosis of EIB is focused on medical history and on pulmonary function testing after standardized exercise testing protocols on treadmill, cycle ergometer or by free running. Non-pharmacological and pharmacological prophylactic measures are the most important approach in the therapy of EIB. Inhalation of beta 2-agonists or cromolyns is the first choice in pharmacological prevention of EIB. With adequate therapy, symptoms of EIB can be controlled enough to maintain everyday as well as sports activities.

[Pneumothorax as a complication to occupational asthma]

A case of occupational asthma complicated by pneumothorax is reported. The disease was caused by work at a fish filleting station. The diagnosis was based on measurements of lung function and specific IgE against plaice. Occupational asthma must be considered in workers exposed to organic dust and the serious potential consequences of prolonged exposure be borne in mind.

Exercise-induced bronchoconstriction depends on exercise load

Exercise-induced bronchoconstriction (EIB) is often used as a measure of bronchial hyperresponsiveness and employed in epidemiological studies. Different tests are used, including free running tests with poor standardization of exercise load. The present study aimed to assess the role of exercise load in relationship to level of EIB.

METHODS

20 asthmatic children, 9-17 years old with a history of EIB, underwent two treadmill test with 85% and 95% exercise load. The children ran with increasing speed for the first 2 min until reaching a heart rate of 85% or 95% of calculated maximum (220-age) and maintained this speed for the last 4 min. Lung function was measured before running, and 0, 3, 6, 10 and 15 min after the run. Borg scale for perceived exertion was employed for children's self-evaluation of exercise load.

RESULTS

Peak heart rate, mean Borg score during 85% exercise load was 178.7/13.6 and during 95% was 194.3/18.2 (P<0.001). Maximum fall in FEV1 after 85% exercise load was 8.84% vs. 25.11% after 95% (P<0.001). Nine subjects (40%) fell > or = 10% in FEV1 after 85% exercise load vs. 20 subjects (100%) after 95% exercise load. EIB from the 95% exercise load test had markedly higher correlation with serum ECP (r=0.77, P<0.001).

CONCLUSION

Exercise load is essential for the interpretation of EIB, and strict standardization of exercise tests should be undertaken. The EIB from the high exercise load tests seemed better correlated to inflammatory activity than the low exercise load test.