Positive Exercise Challenge Test Research Articles

Pulmonary Evaluation in Children with Post-COVID-19 Condition Respiratory Symptoms: A Prospective Cohort Study.

Background: Studies on post-COVID-19 condition (PCC) in adults have shown deterioration in pulmonary function tests (PFTs), mainly a diffusion limitation. Among the pediatric population, data are scarce. Aim: To characterize PFTs in children with PCC, including changes over time. Methods: A prospective longitudinal study of children with defined PCC and respiratory complaints who were referred to a designated multidisciplinary clinic from 11/2020 to 12/2022. Results: Altogether, 184 children with a mean age of 12.4 years (SD 4.06) were included. A mild obstructive pattern was demonstrated in 19/170 (11%) at presentation, as indicated by spirometry and/or positive exercise challenge test and/or reversibility post bronchodilators, only three had a previous diagnosis of asthma. Lung volumes and diffusion were normal in all but one patient (1/134, 0.7%). Exhaled nitric oxide levels were elevated in 32/144 (22%). A total of 33 children who had repeated PFTs had normal or near-normal PFTs on follow-up testing, including seven (21.2%) who had mild obstructive PFTs at presentation. Multivariate analysis identified older age [OR 1.36 (95% CI:1.07-1.75)], specific imaging findings (prominent bronchovascular markings (OR 43.28 (95% CI: 4.50-416.49)), and hyperinflation (OR 28.42, 95% CI: 2.18-370.84)] as significant predictors of an obstructive pattern on PFTs. Conclusions: In children with PCC and respiratory symptoms, the most common impairment was a mild obstructive pattern; most were without a history of asthma. Improvement was witnessed in long-term follow-up. In contrast to the adult population, no diffusion limitation was found. Empirical periodic inhaler therapy may be considered in children with factors associated with PFT abnormalities.

The effect of nose clip on exercise-induced bronchoconstriction in adolescents.

Oral breathing is considered to increase hyper-responsiveness of the airways. Data on the need for nose clip (NC) during exercise challenge test (ECT) in children and adolescents is scarce. Ouraim was to evaluate the role of NC during ECT in children and adolescents. A prospective, cohort study; children referred for ECT were evaluated on two separate visits, with and without a NC. Demographic, clinical data and measurements of lung functions were recorded. Allergy and asthma control were evaluated by Total Nasal Symptoms Score (TNSS) and Asthma Control Test (ACT) questionnaires. Sixty children and adolescents (mean age 16.7 ± 1.1 years, 38% Female,) performed ECT with NC and 48 (80%) completed visit 2 (ECT without NC), 8.7 ± 7.9 days after visit 1. Following exercise, 29/48 patients (60.4%) with NC had a decline of ≥12% in forced expiratory volume in the first second (FEV1 ) (positive ECT) compared to only 16/48 (33.3%) positive tests without NC (p = 0.0008). Test result was changed in 14 patients from positive ECT (with NC) to negative ECT (no NC) and in only one patient from negative to positive. The use of NC resulted in greater FEV1 decline (median 16.3% predicted, IQR 6.0-19.1% predicted vs. median 4.5% predicted, IQR 1.6-18.4% predicted, p = 0.0001), and better FEV1 increase after bronchodil at or inhalation compared to ECT without NC. Higher TNSS scores did not predict higher probability to positive ECT. The use of NC during ECT increases detection rate of exercise induced bronchoconstriction during ECT in the pediatric population. These findings strengthen the recommendation of nasal blockage during ECT in children and adolescents.

The Effect Of Mouth Breathing On Exercise Induced Bronchoconstriction In Children

BACKGROUND: Exercise induced bronchoconstriction (EIB) is a common finding in the pediatric population. Nose breathing is considered to decreases hyper-responsiveness of the airways. Therefore, nose clip (NC) is used during exercise challenge test (ECT) in adults to increase test sensitivity. Data on the need for NC during ECT in children is scarce. Our aim was to evaluate the effect of breathing with and without NC on EIB in children. METHODS: A prospective study evaluating two ECT’s with/without NC within a month period. Demographic, clinical data, Total Nasal Symptoms Score (TNSS) and Asthma Control Test (ACT) were recorded. RESULTS: Fifty-four children (mean age 16.7 ± 1.2 y/o, 39% Female) were evaluated. Forty-four returned to visit 2. At Visit 1 (with NC) baseline FEV1 was 92.8 ± 11.0%pred and 27/44 (61%) had positive ECT (decline≥12% in FEV1) with mean FEV1 drop of 14.7 ± 11.3%pred. At visit 2 ,8.7 ± 7.7 days post visit 1 (without NC), baseline FEV1 was 88.9 ± 11.3%pred (p < 0.001), mean FEV1 drop was 9.0 ± 10.1%pred (p < 0.0001) and only 14/44 (32%) had positive ECT (p < 0.0001). A total of 14/44 (32%) of children with a positive ECT with a NC turned negative without a NC. CONCLUSIONS: Use of NC during ECT increases the rate of positive tests thus possibly improving the yield of EIB diagnosis in children. Optional physiologic mechanisms could be humidification and warming of the inhaled air through the nose cavity. The findings strengthen the recommendation of nasal blockage during ECT. Larger randomized studies are needed to unfold the full effect of nose breathing during exercise.

Short‐ and long‐term effects of fluticasone furoate/vilanterol in exercising asthmatic adolescents: A randomized and open label trial

Relvar® (fluticasone furoate [FF]/vilanterol [VI]) is a once-daily inhaler with bronchodilator effect lasting 24 h. Our aim was to investigate the short- and long-term effects of FF/VI on exercise-induced asthma (EIA) in adolescents. Ninety-three adolescent asthmatics aged 12-18 years were referred for evaluation of EIA. Following a positive exercise challenge test (ECT), 22/44 were allocated to a single administration of salbutamol (400 μg) and 22/44 to FF/VI (92/22 μg) in a double-blind method. Thirty-five subjects were reassessed by repeat ECT 30-60 days of FF/VI. Median FEV1 change post-ECT at baseline was -22.8% predicted (interquartile range [IQR] -26.1 and -18.0) for salbutamol and -21.0 (IQR -30.7 and -16.8) for FF/VI. Following bronchodilator, FEV1 improved similarly in both groups. Repeat ECT following 30-60 days of FF/VI resulted in negative ECT in 33/35 subjects; the median decrease in FEV1 of these 35 subjects was 22.6% predicted (IQR 29-18) before, and 4.6% predicted (IQR 8.7-2.5) after 30-60 days of FF/VI treatment (p < 0.0001). FF/VI is effective in reversing EIA after 15 min in adolescents and in protecting EIA after 30-60 days in adolescents. Larger studies are needed to assess the effect of FF/VI on EIA.

Efficacy and Safety of Omalizumab (Xolair) for Cholinergic Urticaria in Patients Unresponsive to a Double Dose of Antihistamines: A Randomized Mixed Double-Blind and Open-Label Placebo-Controlled Clinical Trial

Cholinergic urticaria (UCOL) is a highly disabling inducible urticaria triggered by an increase in core body temperature. To explore the safety and efficacy of omalizumab in controlling UCOL. We conducted a multicenter randomized mixed double-blind and open-label (first 4 months blinded followed by 8 months open-label) placebo-controlled clinical trial in 22 patients suffering from UCOL who were unresponsive to a double dose of antihistamines. We performed an exercise challenge test during each visit as our main outcome variable. The overall rate of exercise challenge test negative at week 48 was 31.3%, with an average increase in exercise challenge test negative rate of 2.9% points (95% CI, 1.5-4.2) per visit. Statistically significant differences in the negative exercise challenge test rate between the placebo and active intervention groups were not observed during the blinded period (first 4 months of the study). However, from the fourth dose, a progressive improvement was observed. When comparing before and after treatment, statistically significant improvements in all secondary outcome measures were noted after 4 doses (UCOL score: P= .0015; visual analog scale score: P= .0108; days with symptoms: P= .0125) and after 8 doses (UCOL score: P= .0005; chronic urticaria quality of life questionnaire: P= .0105; visual analog scale score: P= .0008; and days with symptoms: P= .0144). In the follow-up visit after the cessation of treatment, the symptoms reappeared, with positive exercise challenge test result and significant increases in all variables. Only 4 of 22 patients remained asymptomatic after 3 months of no treatment. No adverse effects were reported. This randomized mixed double-blind and open-label placebo-controlled trial showed evidence of the safety and potential efficacy of omalizumab in patients with UCOL.

Relation between nasal eosinophilia and airway resistance in patients with persistent rhinitis

Background Bronchial hyper-responsiveness (BHR) is a feature of asthma which can also be found in patients with allergic or nonallergic rhinitis although the exact mechanism is not clear. Objective The aim was to investigate the relationship between nasal eosinophilia and BHR in patients with allergic rhinitis. Patients and methods A total of 26 patients with rhinitis were divided into two groups based on positive exercise challenge test for BHR. Nasal smears and blood samples were obtained to test for nasal eosinophilia and total serum immunoglobulin E, respectively. Results A higher percentage (50%) of patients with BHR demonstrated nasal eosinophilia compared with the group of patients with no BHR (17%). Conclusion This study demonstrates further evidence of the tight relationship between upper and lower respiratory tract in allergic disease.

Role of bronchoprovocation tests in identifying exercise-induced bronchoconstriction in a non-athletic population: a pilot study.

Studies on diagnostic tests for exercise-induced bronchoconstriction (EIB) have centered around the asthmatic and elite athletic population. Traditionally, the exercise challenge test (ET) was recommended to assess EIB. We aimed to compare the performance of surrogate testing, mainly the hypertonic saline (HS) test, and methacholine challenge test (MCT) versus ET in identifying EIB among non-athletic subjects. We prospectively recruited subjects who did not have confirmed active asthma, but who reported exercise-induced dyspnoea. The participants underwent HS and ET on separate days within two weeks. MCT performed within one year were obtained retrospectively from medical records. The sensitivity, specificity, and accuracy of each diagnostic test were calculated using ET as the gold standard. We recruited 27 participants (mean age 20.6±2.5 years; 92.6% male). Five (18.5%) had a history of self-reported asthma prior to recruitment. Eleven participants (40.7%) had a positive ET test. The sensitivity, specificity and accuracy of HS in diagnosing EIB was 90.9%, 62.5% and 74.1%; while that of MCT was 88.9%, 83.3% and 85.7% respectively. Six subjects were positive to HS but had negative ET test. Both HS and MCT were found to be suitable alternatives to ET in screening for EIB in the non-athletic population in this pilot study. Further large scale studies are required to confirm this finding. These tests have the potential to replace ET for the diagnosis of EIB in centres without ET equipment or facilities.

Reported Exercise-Related Respiratory Symptoms and Exercise-Induced Bronchoconstriction in Asthmatic Children.

BackgroundUnlimited physical activity is one of the key issues of asthma control and management. We investigated how reliable reported exercise-related respiratory symptoms (ERRS) are in predicting exercise-induced bronchoconstriction (EIB) in asthmatic children.MethodsIn this prospective study, 179 asthmatic children aged 7 - 15 years were asked for specific questions on respiratory symptoms related to exercise and allocated into two groups according to whether they complained about symptoms. Group I (n = 134) consisted of children answering “yes” to one or more of the questions and group II (n = 45) consisted of children answering “no” to all of the questions.ResultsSixty-four of 179 children showed a positive exercise challenge test (ECT). There was no difference in the frequency of a positive test between children in group I (n = 48) and group II (n = 12) (P = 0.47). The sensitivity of a positive report for ERRS to predict a positive ECT was only 37%, with a specificity of 0.72.ConclusionAccording to current guidelines, the report or lack of ERRS has direct consequences on treatment decisions. However, the history of ERRS did not predict EIB and one-third of asthmatic children without complaints of ERRS developed EIB during the ECT. This raises the question of the need for objective measures of bronchial hyperresponsiveness (BHR) in pediatric asthma management.

An open-label study examining the effect of pharmacological treatment on mannitol- and exercise-induced airway hyperresponsiveness in asthmatic children and adolescents with exercise-induced bronchoconstriction.

BackgroundMannitol- and exercise bronchial provocation tests are both used to diagnose exercise-induced bronchoconstriction. The study aim was to compare the short-term treatment response to budesonide and montelukast on airway hyperresponsiveness to mannitol challenge test and to exercise challenge test in children and adolescents with exercise-induced bronchoconstriction.MethodsPatients were recruited from a paediatric asthma rehabilitation clinic located in the Swiss Alps. Individuals with exercise-induced bronchoconstriction and a positive result in the exercise challenge test underwent mannitol challenge test on day 0. All subjects then received a treatment with 400 μg budesonide and bronchodilators as needed for 7 days, after which exercise- and mannitol-challenge tests were repeated (day 7). Montelukast was then added to the previous treatment and both tests were repeated again after 7 days (day 14).ResultsOf 26 children and adolescents with exercise-induced bronchoconstriction, 14 had a positive exercise challenge test at baseline and were included in the intervention study. Seven of 14 (50%) also had a positive mannitol challenge test. There was a strong correlation between airway responsiveness to exercise and to mannitol at baseline (r = 0.560, p = 0.037). Treatment with budesonide and montelukast decreased airway hyperresponsiveness to exercise challenge test and to a lesser degree to mannitol challenge test. The fall in forced expiratory volume in one second during exercise challenge test was 21.7% on day 0 compared to 6.7% on day 14 (p = 0.001) and the mannitol challenge test dose response ratio was 0.036%/mg on day 0 compared to 0.013%/mg on day 14 (p = 0.067).ConclusionShort-term treatment with an inhaled corticosteroid and an additional leukotriene receptor antagonist in children and adolescents with exercise-induced bronchoconstriction decreases airway hyperresponsiveness to exercise and to mannitol.

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.

Airway response to exercise measured by area under the expiratory flow–volume curve in children with asthma

BackgroundThe exercise challenge test is the gold standard for diagnosing exercise-induced bronchoconstriction; however, it produces negative results in many children with postexercise symptoms. ObjectiveTo assess the utility of the area under the expiratory flow–volume curve (Aex) to identify exercise-induced bronchoconstriction in children with asthma. MethodsData from the medical records of 221 children with asthma who underwent an exercise treadmill challenge (ETC) were analyzed. The relation between exercise-induced respiratory symptoms and results of the ETC were assessed, specifically, the maximal decrease in forced expiration in 1 second (FEV1) and the maximal decrease in the Aex. ResultsThe receiver operating characteristic curve showed that a decrease greater than 6% in the Aex was an optimal cutoff point to produce the fewest misclassified ETC results based on a greater than 10% decrease in FEV1. The results of multivariable logistic regression showed that a decrease greater than 6% in the Aex was comparable to a decrease greater than 10% in FEV1 during an ETC and was more closely related to the presence of exercise-induced respiratory symptoms. Measuring the Aex during a routine ETC allowed a confirmation of bronchoconstriction in an additional 49 children (44%) with asthma and exercise-induced respiratory symptoms. The Aex measurement increased the sensitivity and negative predictive value of ETC without a significant effect on ETC specificity. ConclusionMeasuring the Aex increases the sensitivity and negative predictive value of ETC without producing a significant change in ETC specificity. Applying a 6% decrease in the Aex as a cutoff point for a positive exercise challenge test result may prevent the underdiagnosis of exercise-induced bronchoconstriction in children with asthma and postexercise symptoms. Trial RegistrationThis study was registered at www.clinicaltrials.gov (NCT01798823).

Fractional Exhaled Nitric Oxide Has a Good Correlation with Asthma Control and Lung Function in Latino Children with Asthma

Background. Although the measurement of fractional exhaled nitric oxide (FENO) has been recommended for observational studies and clinical trials of asthma, FENO has not been examined in studies of childhood asthma in Latin America, Objective. To examine the relationship between FENO and indicators of disease control or severity [asthma control test/childhood asthma control test (ACT/C-ACT), lung function, and exercise challenge test (ECT)] in Mexican children with persistent asthma, Methods. Children (6–18 years of age) with persistent asthma were consecutively recruited in a tertiary asthma clinic and divided into two groups, e.g. FENO < 20 parts per billion (ppb) and ≥20 ppb.Adequate FENO measurements were obtained in 134 (83.2%) of 161 eligible children, Results. Children with FENO<20 ppb had significantly higher scores on the ACT/C-ACT than those with FENO ≥ 20 ppb (median [interquartile range] :23 [20.8–25] vs. 21 [18–24], p = .002, respectively). Compared to children with FENO ≥20 ppb, those with FENO <20 ppb had a higher baseline predicted forced expiratory volume (FEV1) [94% (92.5%–99.4%) vs. 83% (81%–89.9%), p = .001] and a lower probability of having a positive ECT (42.7% vs. 71.2%, p = .001). In addition, FENO was significantly inversely correlated with the participants’ ACT/C-ACT score and predicted FEV1, and directly correlated with positive ECT, Conclusion. Among Mexican children with persistent asthma, low levels of FENO ( <20 ppb) are associated with better asthma control, and higher lung function.

Exercise-induced asthma in asthmatic children. Predisposing factors

Exercise-induced bronchoconstriction (EIB) has a high prevalence in children with asthma, and this is a common problem, even in case of controlled asthma, because of the high levels of physical activity in the childhood. The aim of our study was to identify factors associated with the development of EIB in children with controlled asthma. We studied children evaluated for asthma. A personal and familiar history was collected from each patient to estimate asthma severity, precipitating factors, exercise ability, immunotherapy treatment and atopic familiar disorders. Skin prick tests for inhalant allergens, pulmonary function tests (PFTs) and exercise challenge test (ECT) measurements were realized in every patient. We used the Chi Squared test to compare qualitative variables, the Student's-t test for quantitative variables and a logistic regression analysis to estimate the independent effect of the variables. We evaluated 132 asthmatic patients. Eighty-two, 6 to 14 years old (average 110 +/- 36.9 months), were included in the study. Forty one have coughing or wheezing with exercise at least three months ago, in addition to a positive ECT; 9 of these children had solitary EIB (group A), and 32 (group B) had controlled chronic asthma, 27 intermittent and 5 moderately persistent. Forty one controlled asthmatic children, 39 intermittent, 1 mildly persistent and 1 moderately persistent (group C) had a good tolerance for exercise with a negative ECT. No differences were found in familiar history, asthma severity or evolution time in B vs C group. We found that 35 patients (42,68 %) patients were sensitized to indoor allergens: 24 (58,53 %) were patients suffering EIB and 11 (26,8 %) allowed to group C. Precipitating factors of asthma were in group B: respiratory infections in 19 cases, pollen in 20 and in 10 indoor allergens exposure. In group C: 14 patients had asthmatic symptoms with viral respiratory infections, 32 with pollen and 2 with indoor allergens exposure. A patient from group A had allergy rhinitis after exposure to cats. Allergy to indoor allergens demonstrated an direct association to EIB suffering (p = 0,026). Twenty six patients with allergic asthma followed pollen immunotherapy treatment, 7 of group B (33,3 %) and 19 (59,3 %) of group C. This treatment was inversely associated with EIB suffering (p = 0,048). A logistic regression analysis confirmed the independence of both variables as predisposing and protecting factors in EIB suffering. Allergy to indoor allergens might be considered a risk factor for EIB. Immunotherapy treatment could be a protective factor against the development of EIB in children with allergic asthma.

Exercise Challenge Test in 3- to 6-Year-Old Asthmatic Children

The exercise challenge test (ECT) is a common tool to assess exercise-induced asthma (EIA) in school-aged children. EIA has not been explored in the early childhood setting. To assess the existence of EIA in children in this age group. A 6-min, controlled, free-run test was performed in 55 children (age range, 3 to 6 years old) who were classified into the following groups: 30 children in whom asthma had been previously diagnosed (group A); and 25 children with prolonged coughing (group B). Spirometry measurements were obtained before the run, and at 1, 2, 3, 5, 10, and 20 min after the run. A positive finding of EIA was defined as a 13% decrease from baseline FEV(1) or baseline forced expiratory volume in the first 0.5 s (FEV(0.5)). The actual duration of each run was age-related (mean [+/- SD] duration, 4.8 +/- 0.8 min). The nadir in indexes occurred after a mean time of 2.98 +/- 1.31 min. A positive EIA finding determined by FEV(1) was present in 15 children, and by FEV(0.5) in 34 children. Twenty-six children were from group A, but only 8 children were from group B. Wheezing and/or prolonged expiration were associated with a positive test result in 31 of 34 children. Coughing was frequent in children with both negative and positive ECT findings. The present study documents for the first time the presence of EIA in response to a free-run test in early childhood. Our findings suggest that a free-run test for the presence of EIA is suitable, but that the running duration is limited by age. The duration of airflow limitation after exercise is significantly earlier and shorter in young children with asthma compared with older children. FEV(0.5) is a better index than the traditional FEV(1) for describing positive ECT results in young children. The association of wheezing and/or prolonged expiration may help in defining EIA in early childhood in the absence of a spirometer.

Exercise‐induced bronchoconstriction in children with atopic eczema

Non-specific bronchial hyper-responsiveness has been reported in most of the eczematous children even in the absence of asthmatic symptoms. We therefore investigated the occurrence of exercise-induced bronchoconstriction (EIB) in children with atopic eczema (AE) and the predictors of EIB. Fifty-five children referred to the paediatric clinic for AE and a control group of 17 healthy children were recruited. They all carried out a physical examination and skin prick test (SPT) both to inhalant and food allergens, prior to the exercise challenge test. Their parents filled a questionnaire on atopic diseases. They underwent exercise challenge test that consisted in free running for 6 min. Spirometric measurements were carried out before running and till 11 min after. Exercise challenge test was positive in 13 (23%) children with AE. None of the children in the control group had a positive exercise challenge test [OR (95% CI) = 1.31 (1.13-1.51); p = 0.030]. Sixteen (29%) eczematous children had a history of EIB. Such history was not reliable for identifying children who had a positive exercise test. Twenty-nine (52%) children with AE had asthma. Allergic rhinitis affected 33 (60%) of eczematous children and allergic conjunctivitis 28 (50%). EIB was not related to any history of asthma, allergic rhinitis, allergic conjunctivitis, severity of eczema or SPT results. Our study shows that EIB is common in children with AE. Our data also indicate that screening by medical history and physical examination is not a sensitive marker of EIB. This may explain why EIB is often ignored in eczematous children.

Sensitivity of Exercise Testing for Asthma in Adolescents Is Halved in the Summer

The exercise test is one of the most widely used challenge tests for asthma. It is not clear if the sensitivity of this test is lower when patients with asthma are not symptomatic. Since asthma activity is season dependent, with lower activity in the summer, we sought to determine if the percentage of positive exercise test results for asthma is lower in the summer as well. In this retrospective study, the proportion of positive exercise test results for asthma during each of the four seasons of the year, over a 5-year period, was compared. The study was conducted at the pediatric respiratory clinic and pulmonary function laboratory of Shaare Zedek Medical Center. The study group consisted of 532 consecutive patients, all 17 years of age, who were referred for exercise testing for evaluation of suspected asthma. All had normal baseline FEV1 levels, and none received maintenance asthma treatment. Spirometry was performed before and after a standard exercise regimen. A decrease of > or = 10% in FEV1 after exercise was considered positive; 141 patients (26%) had a positive test result. The percentage of positive results in the summer (July to September quartile) was 12.9%, less than half the percentage of positive results during any of the other three quartiles (January to March, 28.9%, p < 0.05; April to June, 30.6%, p < 0.05; October to December, 29.1%, p < 0.05). This study shows that the percentage of positive exercise challenge test results in the summer is half that of any other season. It is likely that the lower percentage of positive results for asthma in the summer reflects the lower sensitivity of the test during this season due to decreased asthma activity. We suggest performing exercise challenge testing only when patients are symptomatic. Physicians caring for patients with symptoms suggestive of exercise-induced asthma whose exercise test results are negative while asymptomatic should consider repeat exercise testing when their patients are symptomatic.

EFFECTS OF NITRIC OXIDE SYNTHASE INHIBITION IN LUNG FUNCTION DURING EXERCISE IN ASTHMATICS

Upon cessation of exercise, pulmonary resistance (RL) and forced expired volume in one second (FEV1) significantly deteriorate in individuals with exercise-induced asthma. However, lung function during exercise is relatively well preserved. Nitric oxide (NO) is a known bronchodilator that might have a protective effect during exercise. METHODS We evaluated changes in RL during 20 min moderate intensity exercise in 17 subjects with FEV1 91% ± 16% predicted and a positive exercise challenge test (reduction in FEV1>15% after exercise breathing dry air). RL was assessed before, during, and up to 15 min after the 20-min exercise on two days; subjects were treated with a nebulized NO synthase inhibitor LNMMA (Ng-monomethyl-L-arginine, 50mg in 2mL saline) or saline in random order, double blinded. RESULTS LNMMA increased RL (81% ± 78% on LNMMA day vs 6.6% ± 28% on saline day, P < 0.01). A decline in RL early in exercise was not prevented by LNMMA, and post exercise increase in RL was similar on the two days (table). There was a slow rise in RL during exercise that was the same on the two days (0.061 ± 0.063 for saline, 0.078 ± 0.078 for LNMMA, units cmH2O/L/sec per min of exercise).TableCONCLUSIONS Our results suggest that NO might regulate baseline airway tone, but it is not further involved in the control of airway function during or after exercise. A dilator influence is present early in exercise, which might be related to mechanical effect of increased tidal volume or respiratory rate. Supported by NIH grants HL52230 and NIH RR-00585

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The exercise test is one of the most widely used challenge tests for asthma. It is not clear if the sensitivity of this test is lower when patients with asthma are not symptomatic. Since asthma activity is season dependent, with lower activity in the summer, we sought to determine if the percentage of positive exercise test results for asthma is lower in the summer as well.In this retrospective study, the proportion of positive exercise test results for asthma during each of the four seasons of the year, over a 5-year period, was compared.The study was conducted at the pediatric respiratory clinic and pulmonary function laboratory of Shaare Zedek Medical Center.The study group consisted of 532 consecutive patients, all 17 years of age, who were referred for exercise testing for evaluation of suspected asthma. All had normal baseline FEV1 levels, and none received maintenance asthma treatment.Spirometry was performed before and after a standard exercise regimen. A decrease of ≥ 10% in FEV1 after exercise was considered positive; 141 patients (26%) had a positive test result. The percentage of positive results in the summer (July to September quartile) was 12.9%, less than half the percentage of positive results during any of the other three quartiles (January to March, 28.9%, p < 0.05; April to June, 30.6%, p < 0.05; October to December, 29.1%, p < 0.05).This study shows that the percentage of positive exercise challenge test results in the summer is half that of any other season. It is likely that the lower percentage of positive results for asthma in the summer reflects the lower sensitivity of the test during this season due to decreased asthma activity. We suggest performing exercise challenge testing only when patients are symptomatic. Physicians caring for patients with symptoms suggestive of exercise-induced asthma whose exercise test results are negative while asymptomatic should consider repeat exercise testing when their patients are symptomatic.

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The exercise test is one of the most widely used challenge tests for asthma. It is not clear if the sensitivity of this test is lower when patients with asthma are not symptomatic. Since asthma activity is season dependent, with lower activity in the summer, we sought to determine if the percentage of positive exercise test results for asthma is lower in the summer as well.In this retrospective study, the proportion of positive exercise test results for asthma during each of the four seasons of the year, over a 5-year period, was compared.The study was conducted at the pediatric respiratory clinic and pulmonary function laboratory of Shaare Zedek Medical Center.The study group consisted of 532 consecutive patients, all 17 years of age, who were referred for exercise testing for evaluation of suspected asthma. All had normal baseline FEV1 levels, and none received maintenance asthma treatment.Spirometry was performed before and after a standard exercise regimen. A decrease of ≥ 10% in FEV1 after exercise was considered positive; 141 patients (26%) had a positive test result. The percentage of positive results in the summer (July to September quartile) was 12.9%, less than half the percentage of positive results during any of the other three quartiles (January to March, 28.9%, p < 0.05; April to June, 30.6%, p < 0.05; October to December, 29.1%, p < 0.05).This study shows that the percentage of positive exercise challenge test results in the summer is half that of any other season. It is likely that the lower percentage of positive results for asthma in the summer reflects the lower sensitivity of the test during this season due to decreased asthma activity. We suggest performing exercise challenge testing only when patients are symptomatic. Physicians caring for patients with symptoms suggestive of exercise-induced asthma whose exercise test results are negative while asymptomatic should consider repeat exercise testing when their patients are symptomatic.