Exercise-induced airflow obstruction in a healthy military population

Exercise-Induced Bronchoconstriction in Iraq and Afghanistan Veterans With Deployment-Related Exposures

INTRODUCTION

Acute exposure to high-levels of ambient fine particulate matter while exercising results in airway narrowing, but the long-term effects of repeated exposure on exercise-induced bronchoconstriction (EIB) are not well known. The goal of this preliminary study is to determine the rate of EIB among a sample of non-treatment seeking veterans deployed to Iraq and Afghanistan.

MATERIALS AND METHODS

Twenty-four veterans (median [interquartile range]: 35.0 [27.3, 45] years) without history of asthma volunteered for this study. Spirometry was assessed before and after a standardized exercise challenge. A positive EIB response was defined as an exercise-induced fall in forced expiatory volume in 1 second ≥10%. Secondary criteria (peak flow ≥10% or mid-expiratory flow ≥15%) were also considered as an estimate of probable EIB.

RESULTS

A positive EIB response was observed in 16.7% and probable EIB response was observed in 41.7% of our sample. Median deployment length to Iraq or Afghanistan was 13.0 [10.3, 17.5] months and the median time since deployment was 4.2 [2.7, 7.7] years. At the time of testing, veterans reported persistent cough (58.3%), wheeze (37.5%), and shortness of breath (37.5%). During deployment, veterans reported exposure to dust and sand (70.8%), smoke from burn pits (66.7%), vehicle exhaust (83.3%), and regional air pollution (26.0%) on most days or daily.

CONCLUSIONS

Approximately 17% of our sample of non-treatment seeking deployed Iraq and Afghanistan veterans demonstrated EIB, similar to the general population prevalence. However, persistent respiratory symptoms and alternative indices of probable EIB supports continued monitoring of this population.

Regional lung function testing in children using electrical impedance tomography

OBJECTIVE

To evaluate regional lung function in lung-healthy children before and after exercise challenge using electrical impedance tomography (EIT).

METHODS

Regional lung function was examined using EIT in 100 lung-healthy children (three age subgroups: 74-121, 122-155, 156-195 months) at baseline and 10 min after exercise. Global lung function was assessed by spirometry using Z-Scores of FEV₁ , FVC, FEV₁ /FVC, and FEF₇₅ . The same lung function measures were determined in 912 EIT image pixels to enable the spatial and temporal ventilation distribution analysis. Coefficients of variation (CV) of these pixel values were calculated and histograms of pixel FEV₁ /FVC and times required to exhale 50% and 75% of pixel FVC (t₅₀ and t₇₅ ) generated. Additionally, we compared the findings of the studied population with three cystic fibrosis (CF) children.

FINDINGS

Z-Scores corresponded to the worldwide reference values in all studied age groups at baseline. Global lung function was not affected by exercise, only the youngest group exhibited higher FVC and lower FEF₇₅ , FEV₁ /FVC attributable to the training effect. The overall degree of ventilation heterogeneity assessed by CV showed no exercise dependency. The histograms of pixel values of FEV₁ /FVC, t₅₀ , and t₇₅ revealed a slight modulating effect of exercise on regional ventilation distribution in all subgroups. EIT identified the distinctly higher ventilation heterogeneity in the CF children.

CONCLUSION

Global and regional lung functions were not affected by exercise in lung-healthy children. Exercise did not increase ventilation inhomogeneity. The obtained EIT-derived regional lung parameters can serve as reference values for future studies in children with lung diseases.

Methacholine challenge is insufficient to exclude bronchial hyper-responsiveness in a symptomatic military population

BACKGROUND

Bronchial hyper-responsiveness in a military population has been evaluated by direct and indirect challenge methods. We hypothesized that negative methacholine challenge testing (MCT) was not sufficient to exclude significant bronchial hyper-responsiveness in a symptomatic military population with exertional dyspnea. The purpose of our study was to identify bronchial hyper-responsiveness in symptomatic military recruits and active duty personnel with normal baseline spirometry and negative pharmacologic bronchoprovocation testing.

METHODS

We performed a retrospective single center electronic chart review of symptomatic service members with a negative MCT who completed a subsequent exercise challenge test (ECT).

RESULTS

ECT was positive in 45 (26.4%) of 171 subjects (98 recruits). Subjects with a positive ECT had lower baseline forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and FEV1/FVC than those with a negative ECT, and these differences were statistically significant. The mean drop in FEV1 with exercise challenge positive patients was 17.9 ± 9.2%, and the mean drop in FEV1 with MCT was significantly greater in exercise challenge positive patients (-9.5 ± 5.5 vs. -7.6 ± 5.5, p = 0.042). Exercise-induced bronchoconstriction (EIB) was observed in 41% of all recruits who subsequently did not complete training. Only 1 recruit subject of 28 with EIB completed training.

CONCLUSIONS

Methacholine challenge is an insufficient screening test to detect bronchial hyper-responsiveness in a symptomatic military population. In military recruits, EIB is associated with training failure.

Exercise induced bronchospasm in physically fit female students of Kerman University and their pulmonary function tests

INTRODUCTION

High prevalence of respiratory symptoms and bronchial hyper-responsiveness has been reported in professionals athletes, particularly in relation to climate and environment. However, the airway response to exercise in active population has been poorly investigated especially in women. The aim of this study was to examine pulmonary function test changes in physically fit female students of Kerman University.

METHODS

Sixty physically fit female students (19 ± 1.12 years old) were randomly selected out of 500 students. Each subject underwent the physical fitness test (Couper test) of the maximal distance running in 12 min. The exercise induced bronchospasm (EIB) symptoms including coughing, wheezing, chest tightness, dyspnea, previously diagnosed asthma and allergy, the use of anti-asthmatics medication and the family history of asthma were recorded using a questionnaire. Pulmonary function tests including; forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), peak expiratory flow (PEF), and maximal expiratory flow at 50% of the FVC (MEF(50)) were measured at rest (baseline), immediately, 5, and 15 min after an exercise test.

RESULT

The result of this study showed that the prevalence of the symptoms of EIB was 40.0%. There was not any significant difference in baseline PFT values between symptomatic and asymptomatic subjects. However, All PFT values of symptomatic subjects were significantly lower than asymptomatic immediately after exercise (p < 0.05 to p < 0.01). In addition, PFT values were significantly reduced in all times intervals for the symptomatic subjects (p < 0.05 to p < 0.01).

CONCLUSION

The results showed a high prevalence of respiratory symptoms and EIB in healthy female students.

Salt intake, asthma, and exercise-induced bronchoconstriction: a review

Despite the heterogeneous treatment options for patients with asthma, there remains a substantial burden of unaddressed disease, even with optimal treatment. Epidemiological studies indicate that patients frequently resort to complimentary and alternative therapies when being treated for asthma and other chronic health conditions. Changes in diet associated with the development of a more affluent lifestyle is one of the environmental factors considered to contribute to the increased prevalence of asthma in the past few decades. Dietary sodium in particular has been considered to be a dietary constituent implicated in this phenomenon. This article reviews the studies conducted that have questioned whether reducing dietary salt intake potentially improves pulmonary function and airway hyper-responsiveness in asthmatics, as well as studies evaluating dietary salt intake on the severity of exercise-induced bronchoconstriction (EIB). The data presented supporting dietary salt restriction for reducing airway hyper-responsiveness in asthmatics is encouraging, though not clinically convincing. Studies conducted previously have been limited for a variety of reasons, including limitations related to the experiment and populations studied. However, in studies that evaluated the severity of EIB in asthmatic individuals and involved altered dietary salt intake, data have been more convincing. A low-sodium diet maintained for 1 to 2 weeks decreases bronchoconstriction in response to exercise in individuals with asthma. There are no data regarding the longer-term effects of a low-sodium diet on either the prevalence or severity of asthma or on EIB. As a low-sodium diet has other beneficial health effects, it can be considered a therapeutic option for adults with asthma, although it should be considered as an adjunctive intervention to supplement optimal pharmacotherapy, and not as an alternative.

Diagnostic tests for asthma in firefighters

BACKGROUND

Subjects with asthma do not meet medical requirements for professions such as firefighting.

OBJECTIVE

To prospectively determine the diagnostic value of respiratory symptoms and various tests used in the assessment of asthma in a cohort of firefighters.

METHODS

A questionnaire, spirometry, direct and indirect airway challenge tests, exhaled nitric oxide, and skin-prick tests were administered prospectively to 101 of 107 firefighters employed in Basel, Switzerland. Asthma was defined as the combination of respiratory symptoms with airway hyperresponsiveness.

RESULTS

Six of 101 firefighters (6%) had physician-diagnosed asthma, which could be confirmed in 4 firefighters. In contrast, asthma was diagnosed in 14% (14 of 101 firefighters). Wheezing was the most sensitive symptom for the diagnosis of asthma (sensitivity, 78%; specificity, 93%). Other respiratory symptoms showed a higher specificity than wheezing but a markedly lower sensitivity. Bronchial airway challenge with mannitol was the most sensitive (92%) and specific (97%) diagnostic test for asthma. Using a cutoff point of 47 parts per billion, nitric oxide had a similar specificity (96%) but lower sensitivity (42%) compared to the direct (methacholine) and indirect (mannitol) airway challenge tests.

CONCLUSION

Asthma was considerably underdiagnosed in firefighters. The combination of a structured symptom questionnaire with a bronchial challenge test allows to identify patients with asthma and should routinely be used in the assessment of active firefighters and may be of help when evaluating candidates for this profession.

Increased airway hyperreactivity with the M40 protective mask in exercise-induced bronchospasm

OBJECTIVE

Exercise-induced bronchospasm (EIB) has a prevalence of 6% to 7% in United States Army personnel and 3% to 13% in professional athletes. There are reported concerns that military personnel with EIB will have increased airway hyperreactivity or significant dyspnea while wearing the standard military M40 protective mask. The objective of this study is to determine whether the M40 protective gas mask increases airway hyperreactivity in military personnel with exertional dyspnea and the diagnosis of EIB.

METHODS

Ten active duty military with EIB (defined as history of exertional dyspnea, normal spirometry, and reactive methacholine challenge test) and 10 normal control subjects were evaluated. Both the participants and control subjects underwent baseline exercise challenge testing (ECT) with and without the M40 protective mask. Forced expiratory volume in one second (FEV1) (percent predicted) post ECT was compared to baseline FEV1 within and between groups along with exercise time.

RESULTS

There was no statistical difference in between individuals and between groups wearing the M40 mask. None of the study group had a positive ECT exercising without the M40 mask while 20% of the study group with EIB had a positive ECT wearing the M40 mask.

CONCLUSION

Military personnel with EIB who exercised with the M40 protective mask did not overall have significantly increased airway hyperreactivity compared to control subjects. Screening ECT may be beneficial in identifying those susceptible persons who report symptoms while wearing the M40 protective mask.

Questionnaire responses that predict airway response to hypertonic saline

BACKGROUND

Airway hyperresponsiveness to hypertonic saline (HS) is associated with airway inflammation. We investigated if responsiveness to HS was predicted by asthma symptoms in the last 3 months.

OBJECTIVES

To investigate if responsiveness to HS can be estimated by questionnaire items investigating asthma symptoms of the last 3 months.

METHODS

Six hundred and four patients with physician-diagnosed asthma being assessed for asthma severity were studied. Bronchial provocation with 4.5% saline was performed, and a questionnaire was administered. The response to 4.5% saline was reported as the provoking dose to cause a 15% fall in the forced expiratory volume in 1 s FEV(1) (PD(15)) and the response-dose ratio (RDR).

RESULTS

Based on the GINA guidelines, asthma severity was intermittent in 497 patients, mild in 107 patients, moderate in 3 patients and severe in 1 patient. A PD(15) to 4.5% saline was recorded in 234 of the 604. Questions on self-recognition of asthma, dust as a trigger, food as a trigger, and frequency of bronchodilator use were significant predictors for a PD(15), and currently taking steroids decreased the likelihood of a positive response to 4.5% saline. Using a multiple-linear regression model, a difference in the RDR could be calculated between those who answered positively compared with the reference group, who answered negatively. This difference could be used as a guide for predicting abnormal reactivity. An increase in RDR in response to 4.5% saline, compared with the reference group, was demonstrated in the presence of self-recognition of asthma severity, dust and cats as a trigger or use of bronchodilator during sleep hours.

CONCLUSIONS

Because of the high positive predictive value of HS for identifying patients with asthma it might be that the need for bronchodilator use at night not only predicts airway hyperresponsiveness to HS, it also could reflect the severity of asthma.

Airway hyperresponsiveness by methacholine challenge testing following negative exercise challenge

BACKGROUND

Exercise challenge testing (ECT) to diagnose exercise-induced bronchospasm has been demonstrated to be an insensitive screening test to demonstrate the presence or absence of airway hyperreactivity. Previous studies have not compared this procedure to methacholine challenge testing (MCT) in a clinical setting.

OBJECTIVE

To determine the frequency of positive MCT in subjects with exertional dyspnea, normal baseline spirometry, and negative ECT.

METHODS

Observational study of 215 military patients at an Army Community Hospital referred for evaluation of exertional dyspnea with normal baseline spirometry. Subjects were further evaluated with ECT on a graded treadmill with pre- and postexercise spirometry. Those without evidence of bronchial hyperreactivity as defined by a 15% decrease in FEV1 postexercise were evaluated with methacholine challenge testing (MCT).

RESULTS

Two hundred ten military subjects were evaluated. Eighty-two patients underwent ECT as the only method of bronchoprovocation testing with 25 positive tests (57 were negative but not referred for further testing). The remaining 128 patients with a negative ECT underwent MCT. Seventy-six (59%) had a negative MCT and 52 (41%) had a positive MCT. Of the positive MCT studies, 74% were positive at a methacholine concentration of 2.5 mg/mL or less.

CONCLUSIONS

Our study demonstrates that a significant number of patients being evaluated for exertional dyspnea will have a positive MCT after a negative ECT. Our findings lead us to question the utility of ECT as an initial diagnostic test for the exercise-induced bronchospasm.

Exhaled nitric oxide as a predictor of exercise-induced bronchoconstriction

INTRODUCTION

Exercise-induced bronchoconstriction (EIB) is present in 40 to 90% of patients with asthma. Exhaled NO (eNO) levels have been correlated with bronchial hyperresponsiveness to methacholine, and have correlated with the degree of decrease in FEV(1) with exercise. The purpose of our study was to examine whether eNO measurements prior to or after exercise could be used as a surrogate marker of exertional bronchoconstriction in a population referred specifically for the evaluation of EIB.

METHODS

We studied 50 consecutive subjects without a history of asthma who were referred for the clinical evaluation of EIB. eNO levels were measured prior to exercise challenge and every 5 min for a total of 30 min after exercise. Forced expiratory flows were measured prior to and serially after exercise challenge.

RESULTS

Seven subjects had a decrease in FEV(1) of > or = 15% with exercise. The mean eNO level prior to exercise was 41 parts per billion (ppb) [median +/- SD, 23 +/- 42.2 ppb] in the EIB group and 25.6 ppb (median, 19.95 +/- 18.47 ppb) in the group without EIB. A receiver operator characteristic curve yielded a value of 0.636. When using an eNO level of < 12 ppb, the sensitivity, specificity, negative predictive value, and positive predictive value for EIB were 1.0, 0.31, 0.19, and 1.0, respectively; therefore, no one with a baseline eNO of < 12 ppb demonstrated EIB.

CONCLUSIONS

No subjects with very low pre-exercise eNO levels (< 12 ppb) demonstrated bronchial hyperresponsiveness to exercise. eNO measurement may obviate the need for bronchoprovocation testing in patients who complain of exertional dyspnea.

Use of aerosols for bronchial provocation testing in the laboratory: where we have been and where we are going

Bronchial provocation testing with pharmacological agents that act directly on airway smooth muscle has important limitations. These include the inability to identify exercise-induced asthma (EIA), to differentiate the airway hyperresponsiveness (AHR) of airway remodelling from the AHR of active inflammation and to differentiate between doses of steroids. Recent studies show that tests that act indirectly to narrow airways are more sensitive than pharmacological agents for identifying airway inflammation and response to treatment. Adenosine monophosphate (AMP) is an indirect challenge that acts on mast cells to cause release of mediators. Hypertonic saline is another and, since its development in the 1980s, has become widely used in Australia. Hypertonic (4.5%) saline is used to identify those with active asthma, those with EIA and those who wish to enter certain occupations or sports (e.g., diving). The recent development, again in Australia, of a test that uses dry powder mannitol has promise for use in the laboratory, the office, or for testing in the field. AHR to mannitol identifies people with EIA and is an estimate of its severity. The mannitol response is modified by drugs used to prevent EIA, implying that similar mediators are involved. A mannitol test can be used to monitor response to steroids and is more sensitive than histamine for identifying persistent airway hyperresponsiveness in asthmatics well controlled on steroids. These findings suggest that indirect challenges give more useful clinical information about currently active asthma and the response to treatment than direct challenge and they will become more widely used.

Evaluation of T factor, surgical method, and prognostic factors in central type lung cancer

OBJECTIVE

We report our experience in the diagnosis and surgical treatment of central type lung cancer (CTLC) and discuss the prognostic significance of clinicopathological factors including the T factor.

METHODS

Subjects were 151 patients with CTLC undergoing surgery from 1984 to 1999. Surgical procedures include lobectomy in 111, pneumonectomy in 35, and segmentectomy in 5. Bronchoplasty was done in 44, including sleeve lobectomy in 33, carinal resection in 8, and bronchoplasty without resection of pulmonary parenchyma in 3. Data on CTLC was compared to that on peripheral lung cancer during the same period.

RESULTS

Compared to peripheral tumors, central lung tumors showed a higher ratio in male gender, pN1 in pN factors, squamous cell carcinoma in histology, and pneumonectomy and bronchoplasty in surgery. No statistical differences were seen between groups in surgical outcome, mean age, distribution pattern in pT factors, and extended surgery. The positive predictive cT factor has improved. No significant difference was seen in 5-year survival based on 8 factors--period, cT factors, tumor histology, bronchoplasty, extended surgery, cellular atypia, additional chemotherapy, and radiotherapy. Five-year survival differed significantly for 12 other factors--pT, cN, and pN factors; surgical method; number of resected organs in extended surgery; curability (complete/incomplete); tumor size; N1 and N2 station metastasis; p factor, and blood vessel and lymphatic invasion. Multivariable analysis indicated only 2 independent prognostic factors--cN and p factor.

CONCLUSIONS

CTLC appears to belong to a subgroup other than peripheral tumors, requiring a more accurate diagnosis of cT factors, particularly in the proximal bronchus, because cT and cN factors are the only 2 used preoperatively.

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.

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.

The prevalence of exercise-induced bronchospasm among US Army recruits and its effects on physical performance

STUDY OBJECTIVES

To measure the prevalence of exercise-induced bronchospasm (EIB) and to determine its effect on the physical performance response to training in otherwise healthy young adults.

DESIGN

Observational, retrospective study.

SETTING

Fort Jackson, SC, May to July 1998.

PARTICIPANTS

One hundred thirty-seven ethnically diverse US Army recruits undergoing an 8-week Army basic training course.

MEASUREMENTS AND RESULTS

Subjects underwent exercise challenge testing at the end of basic training to evaluate for EIB (defined as a decrease in FEV(1) of > or = 15%, 1 or 10 min after running to peak oxygen uptake on a treadmill). Those subjects who were unable to run to peak oxygen uptake, or who were unable to perform two baseline FEV(1) maneuvers the results of which were within 5% of each other, were excluded from analysis. We measured peak oxygen uptake on a treadmill and the scores achieved on the components of the US Army physical fitness test (APFT). Of 137 subjects, 121 (58 men and 63 women) met our inclusion criteria. Eight subjects (7%) had EIB. Subjects who experienced EIB and unaffected control subjects both showed statistically significant gains in performance on the APFT events during basic training. At the end of basic training, peak oxygen uptake levels and APFT event scores were not significantly different between subjects with EIB and unaffected control subjects.

CONCLUSIONS

Seven percent of the US Army recruits who were tested had EIB, but this did not hinder their physical performance gains during basic training. EIB per se should not be an absolute reason to exclude individuals from employment in jobs with heavy physical demands.

Occurrence of exercise induced bronchospasm in elite runners: dependence on atopy and exposure to cold air and pollen

OBJECTIVES

To study factors affecting the occurrence of exercise induced bronchospasm (EIB) in elite runners.

METHODS

Fifty eight elite runners, 79% of them belonging to Finnish national teams, volunteered. The athletes answered a questionnaire on respiratory symptoms. Skin prick tests were used to investigate atopy, and spirometry to examine lung function at rest and after an exercise challenge test (ECT) at subzero temperature in the winter and after a similar ECT in the summer at the end of the birch pollen season.

RESULTS

Definitive EIB (a post-exercise reduction of 10% or more in forced expiratory volume in one second (FEV1) was observed in five (9%) of the 58 runners. A subgroup consisting of 19 non-atopic symptom-free runners with no family history of asthma was used to establish a normal range for post-exercise reduction in FEV1. When this group's mean exercise induced change in FEV1 minus 2 SDs (a reduction of 6.5% or more in FEV1) was taken as the lower limit of the reference range, 15 (26%) of the runners had probable EIB in either the winter or the pollen season. The occurrence of probable EIB depended on atopy (odds ratio increased with number of positive skin prick test reactions, p < 0.05). Nine (22%) of the 41 runners, challenged in both the winter and the pollen season, had probable EIB only in the winter, and three (7%) had it only in the pollen season. Only one runner (2%) had EIB in both tests.

CONCLUSIONS

Mild EIB is common in Finnish elite runners and is strongly associated with atopy. Seasonal variability affects the occurrence of EIB, and thus exercise testing should be performed in both cold winter air and the pollen season to detect EIB in elite runners.

Challenge tests to assess airway hyperresponsiveness and efficacy of drugs used in the treatment of asthma

Bronchial provocation tests are useful to diagnose and assess severity of asthma and to follow response to treatment. The tests used include those stimuli that act "directly" on receptors causing contraction of airway smooth muscle, e.g., pharmacological agents, and those stimuli that act "indirectly" by causing release of endogenous mediators that cause the airways to narrow. These "indirect" stimuli include physical ones such as airway drying from hyperpnea and changes in airway osmolarity from inhaling aerosols of water and hyperosmolar saline. Indirect stimuli cause the airways to narrow in response to endogenously released substances from inflammatory cells or nerves and responses are thought to reflect the presence and severity of inflammation of asthma. Challenge with hyperosmolar saline is now being used as an indirect test because it also identifies persons with exercise-induced asthma and is appropriate to assess suitability for diving with SCUBA. Hyperosmolar challenge is also useful to assess the effect of both the acute and chronic treatment with antiinflammatory drugs. This, combined with the potential to collect inflammatory cells in sputum induced by the same stimulus should result in this challenge being more widely used, not only in the hospital laboratory but also in epidemiology and occupational asthma.

Exercise-induced asthma and the use of hypertonic saline aerosol as a bronchial challenge

Exercise induced asthma is a common complaint and the prevalence appears to be increasing worldwide. Once confined to the research domain of university teaching hospitals, the study of EIA has extended into the school playground, defence force establishments and sports institutions. Standardized protocols have been developed to study EIA in the laboratory and in the field. A surrogate challenge using eucapnic or isocapnic hyperventilation with dry air is becoming popular because it has advantages over exercise, at least for adults. The stimulus that leads the airways to narrow is caused by the inhalation of dry air during hyperventilation and exercise, during which water is evaporated from the airways in order to condition the inspired air. The mechanism whereby the airways narrow is thought to be due to the dehydrating effects of water loss, particularly in relation to its potential to cause the airways to become hyperosmolar. Mast cell mediators such as histamine and the leucotrienes are probably involved in EIA because specific antagonists reduce severity. As a result of the osmotic theory of EIA, studies were carried out to determine whether subjects with EIA were sensitive to the effects of increasing airway osmolarity by inhalation of hyperosmolar aerosols of sodium chloride. A challenge protocol using an aerosol of 4.5% sodium chloride, generated from an ultrasonic nebulizer, has been used to identify persons with asthma and to assess response to drug therapy. There are many similarities between responses to exercise, hyperventilation and hypertonic saline in the physiological and biochemical responses and the responses to drugs. Challenge with hypertonic saline is easier and cheaper to use because expensive equipment and a source of dry air is not required as with exercise or hyperventilation. The ability to obtain a dose-response curve rather than a single response and the ability to collect inflammatory cells at the same time make challenge with hypertonic saline an attractive technique to study patients suspected of having asthma.

Exercise-induced asthma and anaphylaxis

With increased popularity in exercise, the number of individuals with exercise-induced asthma (EIA), or 'exercise-induced bronchospasm', has increased due to an increased awareness among physicians of the clinical symptoms associated with EIA. EIA affects approximately 75 to 95% of asthmatic patients. 40% of children with allergic rhinitis have EIA, whereas only 3 to 11% of nonasthmatics have EIA. Although athletes with asthma have been recognised for years, EIA in nonasthmatic individuals has gained recognition since the 1984 Olympics. Vague symptoms of recurring poor performance, fatigue despite adequate conditioning, or 'getting winded' during an athlete's usual workout may be the presenting complaints. Athletes may be more likely to attribute these symptoms to poor conditioning or an upper respiratory infection, and not seek immediate assistance. Younger athletes may complain of stomach ache or refuse to participate in strenuous play because of an inability to keep up with other children. Additionally, an awareness of exercise-induced anaphylaxis needs to be considered when discussing aspects of airway compromise following exercise; however, its presentation is more urgent than those with EIA. Although the pathophysiology of EIA is somewhat controversial, the most likely explanation is a combination of heat and water loss leading to mediator release. The different medications that have been used to treat EIA are based on theories regarding the bronchial hyperreactivity of EIA.