Comparison of three different preparations of disodium cromoglycate in the prevention of exercise-induced bronchospasm: a double-blind study

In its usual form, disodium cromoglycate (DSG) contains lactose as a carrier (DSGL +). It has been suggested that lactose may effect irritant receptor sites, thus causing a degree of bronchoconstriction or less blocking of exercise-induced bronchospasm (EIB). This study was designed to assess and compare the ability of three different forms of DSG to block EIB. Eighteen asthmatic children and adolescents were given either DSGL+ by Spinhaler, DSG without lactose (DSGL-) by Spinhaler, nebulized (and also lactose-free) DSG solution (DSGN), or placebo in a randomized double-blind fashion on four occasions within a 10-day period. Pulmonary function tests were performed before and after medication and again after a standardized treadmill exercise test. After the exercise that followed treatment with each form of DSG the decreases in peak expiratory flow rate (PEFR) and forced expiratory volume in one second (FEV1) were significantly less than that seen after treatment with placebo. There was no significant difference between any of the three preparations of DSG. A complete block of EIB (decreases in PEFR and FEV1 of less than 12.5% and 10%, respectively) was seen in ony 11% of studies using all forms of DSG however, DSG was considered to be 'clinically effective' in 59% of studies.     

Safety of sputum induction with hypertonic saline solution in exercise-induced bronchoconstriction

BACKGROUND: The safety of sputum induction (SI) is well described in stable asthma, but the safety of SI in exercise-induced bronchoconstriction (EIB) has not been established. OBJECTIVES: Our goals were to examine the relationship between the severity of EIB and bronchoconstriction during SI, and to determine if SI conducted after exercise challenge increases the risk of excess bronchoconstriction during SI. METHODS: SI was conducted in 32 patients with mild-to-moderate asthma (baseline FEV(1), 86 +/- 9% of predicted [mean +/- SD]) with EIB (15 to 63% reduction in FEV(1) following exercise challenge) following pretreatment with albuterol using 3% saline solution and repeated on a separate day 30-min after exercise challenge. RESULTS: There was a reduction in peak expiratory flow rate (PEFR) during SI without exercise (mean maximum reduction vs baseline, 4.0% at 10 min; 95% confidence interval [CI], 1.0 to 7.1; p = 0.02) and during SI 30 min following exercise (mean maximum reduction vs baseline, 5.2% at 8 min; 95% CI, 1.0 to 7.5; p < or = 0.01); however, there was no difference between the PEFR reductions during SI without or following exercise challenge. The best predictor of reduction in PEFR during SI was the preprocedure FEV(1), while the severity of EIB was not associated with bronchoconstriction during SI. CONCLUSIONS: We conclude that SI can be performed safely following exercise challenge in asthmatics with EIB, and that the severity of EIB prior to SI is not a major determinant of bronchoconstriction during SI.     

Exhaled nitric oxide and exercise-induced bronchospasm assessed by FEV1, FEF25-75% in childhood asthma.

The relationship between exhaled nitric oxide (eNO) and bronchial hyperresponsiveness (BHR) should be clarified. The aim of this study was to determine the relationship between eNO and exercise-induced bronchospasm (EIB) by estimation of the each lung parameter in asthmatic children who performed a bicycle ergometer exercise test. Twenty children with asthma were recruited. eNO concentration was examined by the recommended online method. To evaluate BHR, an exercise stress test was performed on a bicycle ergometer. The mean baseline eNO value was significantly correlated with the mean maximum % fall in forced expiratory volume in 1 second (FEV1), forced expiratory flow between 25% and 75% (FEF25-75%) after exercise (r=0.53, r=0.65, respectively). eNO in the EIB-positive group was significantly higher than that in the EIB-negative group by assessing FEV1, FEF25-75% (p<0.005, p=0.005). We demonstrated that the most important lung parameter assessed the occurrence of EIB by a bicycle ergometer exercise test was not only FEV1 but FEF25-75%, which significantly correlated with eNO. This suggests that not only FEV1 but FEF25-75% can be used to evaluate the correlations between BHR (EIB) and airway inflammation (eNO) in asthmatic children. A low eNO is useful for a negative predictor for EIB.     

An evaluation of levalbuterol HFA in the prevention of exercise-induced bronchospasm.

BACKGROUND: Exercise-induced bronchospasm (EIB) affects up to 90% of all patients with asthma. Objective. This study evaluated the ability of levalbuterol hydrofluoroalkane (HFA) 90 mug (two actuations of 45 microg) administered via metered dose inhaler (MDI) to protect against EIB in mild-to-moderate asthmatics. METHODS: This was a randomized, double-blind, placebo-controlled, two-way cross-over study. Patients with asthma (n = 15) were > or =18 years, had a > or =6-month history of EIB, > or = 70% baseline predicted forced expiratory volume in 1 second (FEV1), and a 20% to 50% decrease in FEV(1) after treadmill exercise challenge using single-blind placebo MDI. Levalbuterol or placebo was self-administered 30 minutes before exercise. Treatment sequences were separated by a 3-to 7-day washout period. Spirometry was performed predose, 20 minutes postdose/pre-exercise, and 5, 10, 15, 30, and 60 minutes post-exercise. The primary endpoint was the maximum percent decrease in FEV1 from baseline (postdose/pre-exercise). The percentage of protected (< or = 20% decrease in post-exercise FEV1) patients was also assessed. RESULTS: Levalbuterol had significantly smaller maximum percent post-exercise decrease in FEV1 compared with placebo (LS mean +/- SE; -4.8% +/- 2.8% versus -22.5% +/- 2.8%, respectively). For levalbuterol, 14/15 (93.3%) patients had < 20% decrease in post-exercise FEV1 compared with 8/15 (53.3%) for placebo (p = 0.0143). Treatment was well tolerated. CONCLUSION: Levalbuterol HFA MDI (90 microg) administered 30 minutes before exercise was significantly more effective than placebo in protecting against EIB after a single exercise challenge and was well tolerated. CLINICAL IMPLICATIONS: Levalbuterol HFA MDI when administered before exercise was effective in protecting adults with asthma from EIB.     

Exercise-induced bronchospasm among students of Tehran University of Medical Sciences in 2004.

Exercise-induced bronchospasm (EIB) is a clinical syndrome that affects 8-20% of the general population and 11-50% of athletes. Although a variety of testing protocols for the diagnosis of EIB have been pursued, the optimal algorithm still is lacking. The aim of this study was to determine the prevalence of EIB among students of Tehran University of Medical Sciences and to find out whether self-reported symptoms are sufficient to establish the diagnosis of EIB. A total of 463 students completed an EIB symptoms-specific questionnaire, followed by a 9-minute exercise test. Spirometric measurements were performed before, and 6 and 15 minutes after exercise. In our study, decrements of >15% in forced expiratory volume in 1 second or 25% in peak expiratory flow or forced expiratory flow at 25-75% from baseline values were defined as positive indications of EIB. The overall prevalence of EIB was 10.8% (15.94% in men versus 8.62% in women; p = 0.02). There was no significant difference between the students with and without EIB regarding body mass index, family income, and allergy frequency. The frequency of at least two out of the four symptoms of coughing, wheezing, shortness of breathing, and chest pain/discomfort among students with EIB was significantly higher than those without EIB (26.5% versus 15.1%, respectively; p = 0.04). The sensitivity and specificity of self-reported symptoms for EIB diagnosis were 26.5 and 84.9%, respectively. Although among all determinants proposed for EIB, respiratory symptoms are closely related to the disease, diagnosis based on only these symptoms is not recommended because of high false positive and false negative results.     

孟鲁司特钠治疗运动诱发性支气管收缩的临床研究

目的　观察孟鲁司特钠治疗轻、中度支气管哮喘(简称哮喘)并发运动诱发支气管收缩(EIB)或运动性哮喘(EIA)的治疗及预防作用。方法　采用前瞻性开放、自身治疗前、后对照的方法。选择轻、中度哮喘并运动激发试验阳性患者30例,给予孟鲁司特钠每晚10mg治疗1个月。分别于治疗前1d、治疗后3d及4周进行运动激发试验。主要观察运动后的前60min一秒钟用力呼气容积(FEV1)自基线下降的百分比时间曲线下面积(AUC0~60min),运动后FEV1最大下降程度(FEV1最低值)及自最低FEV1恢复至运动前基值5%以内所需的时间(FEV1最低值恢复时间)。结果　孟鲁司特钠治疗前1d、治疗后3d和治疗后4周,运动激发试验后AUC0~60min分别为(39±21)、(13±14)、(12±14)%·min,治疗前、后比较差异有统计学意义(P<001);FEV1最低值分别为(18±06)、(21±06)、(23±08)L,治疗前、后比较差异有统计学意义(P<001);FEV1最低值恢复时间分别为(51±36)、(26±28)、(25±33)min,治疗前、后比较恢复时间显著缩短(P<001),并持续1个月。EIB/EIA患者孟鲁司特钠治疗前、后肺功能[FEV1、峰流速(PEFR)]均可维持接近正常且无明显变化。吸入糖皮质激素不能预防EIB/EIA。结论　孟鲁司特钠对轻度哮喘患者并发EIB/EIA疗效和预防作用显著,而且安全、快捷。     

Prevalence of Exercise-Induced Bronchospasm in Long Distance Runners Trained in Cold Weather

We investigated whether regular training in cold weather has an effect on the development of exercise-induced bronchospasm. Nineteen sedentary males and 20 male long distance runners who were regularly training in Erzurum participated in this study. They had no history of asthma, atopy or allergic rhinitis. Pre- and post-exercise spirometry was performed in the participants in room temperature. EIB was defined as at least a 10% fall in FEV₁ or a 15% fall in FEF_25-75% or a 25% fall in PEFR. EIB was established in 7 of 20 athletes and in 1 of 19 sedentaries. Prevalence of EIB will be higher even if it is established in room temperature when training for the sports like long distance running which is not a cold weather sport. We conclude that it will be more convenient to establish EIB in room temperature and in the laboratory since the exercise test and spirometry can be performed more accurately under more standard conditions.     

Exercised-induced asthma in soccer players ages from 8 to 13 years

The purpose of this study was the detection of exercise induced asthma in soccer players aged 8-13 years. Thirty boys, 8-13 years old participated in the study. They were coming from an athletic team of north of Thessaloniki. The study included clinical examination, administration of a respiratory health questionnaire and the exercise -- free running -- test with spirometric measurements. Spirometric measurements were performed by using a microspirometer, before exercise and 2, 5, 10, 15 and 30 min after a 6 min free running exercise (80 - 90 % max heart rate). The highest forced expiratory volume in one second (FEV (1)) value before exercise was compared with the lowest of post exercise values. The results showed a decline in FEV (1) > 15 % in 12 out of 30 children. Particularly, decline in FEV (1) was present in 1 (11 %) out of 9 children with free personal medical history but positive family history for asthma, in 3 (25 %) out of 12 children with allergies, and in 8 (89 %) out of 9 children with asthma. Symptoms were reported by 9 of 12 children with fall in FEV (1) > 15 %, during the 6 min exercise test, who had no symptoms during the soccer games. Identification of EIA by exercise challenge test in young athletes is a useful component for the diagnosis of bronchial hyperresponsiveness. Similar studies should be performed on older and younger athletes who participate in different sports and games.     

Comparison of the protective effect of formoterol and of salmeterol against exercise-induced bronchospasm when given immediately before a cycloergometric test

BACKGROUND: Salmeterol and formoterol, two long-acting beta(2)-adrenergic agonists, have been shown to be effective against exercise-induced bronchospasm (EIB) several hours after inhalation, but no study has yet compared their protective effect immediately after administration. OBJECTIVES: To compare the protective effect of inhaled formoterol and salmeterol against EIB immediately and 4 h after administration. METHODS: Double-blind, two-period cross-over study of 11 EIB-positive asthmatic subjects (mean age 21.2 years) administered formoterol 24 microg and salmeterol 50 microg by means of metered-dose inhalers (MDIs) on 2 days separated by an interval of 72 h; the subjects performed two cycloergometric exercise tests immediately and 4 h after dosing. Forced expiratory volume (FEV(1)) measurements were made before and at the end of exercise, and then after 3, 5, 10, 15, 20, 25 and 30 min. The maximum percentage decrease in FEV(1) in the 30 min following exercise was considered. RESULTS: Immediately after drug administration, but not 4 h later, formoterol provided significantly better protection against EIB than salmeterol (p = 0.02). The number of formoterol-treated subjects protected against EIB (i.e. with a <15% decrease in FEV(1) after treatment) was 10/11 after the first exercise test and 7/8 after the second; the corresponding figures after salmeterol treatment were 5/11 and 7/8. CONCLUSIONS: Our results show that formoterol inhaled via an MDI is effective in preventing EIB as early as within a few minutes of administration, whereas salmeterol does not offer any appreciable protection. On the contrary, the protective effect of the two drugs is clinically equivalent 4 h after administration.     

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.     

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.     

Influence of water content of inspired air during and after exercise on induced bronchoconstriction.

This study looked at the influence of inspired air water content on exercise-induced bronchospasm (EIB). On separate days, 12 mild asthmatics (4M, 8F), aged 18-39 yrs (mean: 27 yrs), performed four six minute steady-state exercises on ergometer at 80% of their maximum workload. Exercises were randomized to the following inspired air conditions: dry air (0% relative humidity (RH] during exercise followed by dry (DD) or humid air (100% RH) (DH) after exercise, humid air during exercise followed by dry (HD) or humid air (HH). Room temperature was kept constant (22 +/- 1 degree C) at all visits. Forced expiratory volume in one second (FEV1) was measured before and every 5 min for 25 min after exercise. Ventilation (VE) was not significantly different whether the exercise was done under dry or humid air. There was a residual bronchodilatation at the end of exercises performed in humid air, while at this time FEV1 was already lower than baseline when exercise was done in dry air conditions. The maximal fall in FEV1(%) following exercise was significantly greater after those performed in dry air: DD (29 +/- 5.6%) and DH (30 +/- 5.8%) than in humid air: HD (12 +/- 4.9%) and HH (20 +/- 4.9%) (p less than 0.05). The time-course of recovery from bronchoconstriction was significantly improved when inhaling dry air after exercise. However, the difference found in the maximal % fall in FEV1 after exercise when recovery was in dry compared to humid air did not achieve statistical significance. In conclusion, EIB is influenced by the changes in water content during and after exercise. Bronchoconstriction following exercise is minimal if exercise is done in humid air and recovery in dry air, and maximal if the exercise is performed in dry air and recovery in humid air.     

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.     

Applicability of interrupter resistance measurements for evaluation of exercise-induced bronchoconstriction in children

The interrupter technique is a noninvasive method for measuring air-flow resistance during tidal breathing. This method requires minimal cooperation, and is therefore promising for use in uncooperative children. The aim of this study was to evaluate applicability interrupter resistance (Rint) measurements in the assessment of exercise-induced bronchoconstriction (EIB). Fifty children aged 5-12 years with mild to moderate asthma were tested by exercise challenge, consisting of free outdoor running for 6 min at 80-90% of maximal predicted heart rate for age. Rint, forced expiratory volume in 1 sec (FEV1), and peak expiratory flow (PEF) were measured before and 10 min after exercise. EIB was defined as a fall of 10% or more in FEV1 after exercise. The repeatability of Rint was assessed, and its response to exercise challenge was compared with current standardized methods. The mean intermeasurement coefficient of variation was 4.6% (SD, +/- 3.0%), and the repeatability coefficient was 0.056 kPa/l/sec. Eighteen (36%) of the 50 children had EIB after exercise challenge test. The area under the receiver-operating characteristic (ROC) curve was 0.953 (95% confidence interval, 0.853-0.992; P < 0.001), and the optimal Rint cutoff value was 15.2%, producing a sensitivity of 88.9% and a specificity of 96.9%. The positive and negative predictive values were 94.1% and 93.9%, respectively. The kappa value between FEV1 and Rint was 0.83. The repeatability of Rint measurements was good, and the results of exercise challenge tests using Rint measurements have excellent agreement with the current standardized methods to detect EIB. Considering that only minimal comprehension and coordination are needed without forced breathing technique, the Rint measurement can provide a useful alternative for assessment of EIB in children unable to perform reliable spirometry.     

Comparison between peak expiratory flow rate and forced expiratory volume in one second in the evaluation of children suspected to have asthma

This study was conducted to evaluate whether forced expiratory volume in 1 second (FEV1) for the diagnosis of bronchial reactivity by means of the free-running exercise test and bronchodilator inhalation, could be appropriately replaced by simple measurements of peak expiratory flow rate (PEFR) in children.We studied 108 referred symptomatic children (due to chronic cough or wheezing) suspected to have asthma aged 5-14y. Forced breathing spirometry and the "Mini-Wright peak flow meter" tests were recorded before and fifteen minutes after the challenge with free- running exercise or bronchodilator (Salbutamol) inhalation, regarding the baseline FEV1 value (FEV1> 80% considered as normal).There was a high correlation between PEFR and FEV1 (in absolute value and percent predicted) measured before and after bronchodilator inhalation test (r = 0.48, P = 0.05) in comparison to the values referred to free- running exercise test (r = 0.26, P = 0.01)."forced breathing spirometry" and "Mini-Wright peak flow" cannot be used interchangeably for diagnosing asthma, and PEFR measurement should remain a procedure for monitoring and following up the patients.     

Blood eosinophil counts for the prediction of the severity of exercise-induced bronchospasm in asthma

It has been suggested that airway eosinophilic inflammation is associated with the severity of exercise-induced bronchospasm (EIB). Blood eosinophils are known to be an indirect marker of airway inflammation in asthma. The aim of this study is to investigate that a simple and easy blood test for blood eosinphil counts may predict the severity of EIB in asthma. Seventy-seven men with perennial asthma (age range 18-23 years) were included. Lung function test, skin prick test, and blood tests for eosinophils counts and total IgE levels were performed. Methacholine bronchial provocation test and, 24 h later, free running test were carried out. EIB was defined as a 15% reduction or more in post-exercise FEV1 compared with pre-exercise FEV1 value. Atopy score was defined as a sum of mean wheal diameters to allergens. EIB was observed in 60 (78%) of 77 subjects. Asthmatics with EIB showed significantly increased percentages of eosinophils (P<0.01), log eosinophil counts (P<0.001), and atopy scores (P<0.05) and decreased log PC20 values (P < 0.05) compared with asthmatics without EIB. Asthmatics with eosinophils of > 700 microl(-1) (36.9 +/- 12.7%) had significantly greater maximal % fall in FEV1 after exercise than asthmatics with eosinophils of < 350 microl(-1) (24.7 +/- 16.6%, P <0.05). Blood eosinophil counts > 350 microl(-1) yielded the specificity of 88% and positive predictive value of 93% for the presence of EIB.When a multiple regression analysis of maximal % fall in FEV1 according to log eosinophil counts, log PC20, log IgE and atopy score was performed, only blood eosinophil counts were significant factor contributing to the maximal % fall in FEV1 after exercise. These findings not only suggest that a simple blood test for eosinophils may be useful in the prediction of the severity of EIB, but also reinforce the view that airway eosinophilic inflammation may play a major role in EIB in asthma.     

Prevalence Rate of Exercise-Induced Bronchoconstriction in Annaba (Algeria) Schoolchildren

Background. We studied the prevalence rate of exercise-induced bronchoconstriction (EIB) in Annaba schoolchildren. No previous assessment of this syndrome had ever been done in Algeria. Methods. EIB was evaluated using the 6 min free running test (6MFRT) on 286 children, 87.4% of whom were 10–12 years old. They performed the test in the morning, during the autumn–winter season. Peak expiratory flow rate (PEFR) was measured before, and then 5 and 10 min after the 6MFRT, a 15% or more decrease in post-exercise PEFR being defined as significant. Results. EIB was much more frequent in asthmatic than in nonasthmatic children (47.0% vs. 13.9%, p < .001) and the drop in PEFR was more marked among the former. EIB was observed more often in a cool temperature (<8°C). There were relatively more children who were either eutrophic or overweight among those presenting an EIB. Past histories of nocturnal wheezing and rhinoconjunctivitis presented respectively the best specificity (96.7%) and sensitivity (84.8%). Children of unemployed workers presented the highest occurrence of EIB. Passive smoking appeared as the only factor being related to EIB among the indoor pollutants. The prevalence rate of asthma (6.7%) was higher than in a previous cross-sectional epidemiological survey study performed in the Maghreb. The prevalence rate of EIB (13.9%) was situated in the upper range of the results given worldwide. Conclusions. These features of a fairly high bronchial hyperresponsiveness could be facilitated by the polluted environment of the city.     

Onset and duration of attenuation of exercise-induced bronchoconstriction in children by single-dose of montelukast

Single-dose montelukast attenuates exercise-induced bronchoconstriction (EIB) in adults within 2 hours postdose and lasting through 24 hours. This study evaluated the onset and duration of EIB attenuation in children after a single dose of montelukast. A randomized, double-blind, placebo-controlled, two-period crossover study was performed. Patients (n = 66) aged 4-14 years, with preexercise forced expiratory volume in 1 second of (FEV(1)) ≥70% predicted and maximum percentage fall in FEV(1) of ≥20% at two screening exercise challenges were eligible. Patients were to receive single-dose montelukast (4 or 5 mg) or placebo before performing standardized exercise challenges at 2 and 24 hours postdose. A 3- to-7-day washout separated the two crossover periods. The primary end point was maximum percentage fall in FEV(1) after exercise challenge 2 hours postdose. Secondary end points included maximum percentage fall in FEV(1) after the 24-hour postdose challenge; each of the following at 2 and 24 hours postdose-maximum percentage fall in FEV(1) categorized as <10%, 10-20%, or >20%; area under the curve (AUC) during 60 minutes postchallenge; time to recovery of FEV(1) to within 5% of preexercise baseline; and need for rescue medication. The mean maximum percentage fall in FEV(1) after the 2-hour postdose exercise challenge was significantly attenuated after single-dose montelukast compared with placebo (15.35% versus 20.00%; p = 0.020). Montelukast was also significantly more effective than placebo for maximum percentage fall after the 24-hour challenge (12.92% versus 17.25%; p = 0.005), the categorized maximum percent fall in FEV(1) at 2 hours (p = 0.034), and AUC at 2 hours (p = 0.022) and 24 hours (p = 0.013). Single-dose montelukast provided rapid and sustained EIB attenuation in children. Clinicaltrials.gov identifier: NCT00534976.     

Effects of inspired air conditions on catecholamine response to exercise in asthma

The influence of different inspired air conditions on exercise-induced bronchoconstriction (EIB) is well appreciated. However, the mechanism by which this influence is exerted is uncertain. To determine if varied inspired air conditions during exercise could affect the catecholamine response to physical exercise, we had 13 asthmatic and 6 healthy children (aged 10–18 years) undergo two bouts of cycle ergometry tests under different air conditions. One test was done while breathing cold dry (CD) air (temperature, ?20.2°C; relative humidity, 0%) and the other while breathing warm humid (WH) air (temperature, 34.3%; relative humidity, 100%). Forced expiratory volume in 1 second (FEV,) and plasma catecholamine concentrations were recorded before and after exercise. Marked EIB (48 2 5% SEM fall in FEV, from baseline) developed in all asthmatics after the CD exercise, but no EIB was noted after the WH exercise. Normal controls had no EIB under either test conditions. Plasma levels of catecholamines at rest, and the changes that occurred during and after exercise, were comparable within as well as between the groups in both tests. Catecholamines did not rise in asthmatics following development of EIB. These data demonstrate that inspired air conditions do not influence the sympathoadrenal response to exercise, at least as reflected in plasma catecholamine levels. In fact, this response did not differ between asthmatics and normals, irrespective of the development of EIB. These results are consistent with previous reports about impaired catecholamine response of asthmatics to bronchoconstriction. Pediatr Pulmonol. 1994;18:99–103. © 1994 Wiley-Liss, Inc.