Influence of baseline lung function on exercise-induced response in childhood asthma

Evaluation of severity of bronchial asthma through an exercise bronchial challenge

Optimum treatment of bronchial asthma requires accurate diagnosis and severity classification. We studied the use of an exercise bronchial challenge in the asthmatic patient as a diagnostic tool. An exercise bronchial challenge test was carried out in 431 asthmatic children and 114 children without a history of asthma in a moderate-altitude environment (2,230 m above sea level/7,314 feet above sea level). Values of peak expiratory flow (baseline and maximum fall) were analyzed through time in each asthma severity group (intermittent, mild persistent, moderate persistent, severe persistent, and nonasthmatic controls). There was a significant difference among responses of asthma severity groups for almost all variables. No difference was found between nonasthmatic and intermittent groups who had similar behavior, except in bronchodilator response. An exercise bronchial challenge helps classify a patient according to asthma severity; it is easy to reproduce and does not require expensive equipment. It allows diagnosing and classifying asthma severity easily and supplementing the clinical evaluation. Based on our results, we propose a fall of PEF >or= 11% as new cutoff point for making a diagnosis of persistent bronchial asthma. A fall of 11-25% indicates mild persistent asthma; from 25-50%, moderate persistent asthma; and a bigger fall, severe persistent asthma.

A doctor's ability to assess the severity of childhood asthma by simple clinical features

AIMS

To ascertain whether the severity of childhood asthma can be reliably assessed by simple clinical features, 94 newly diagnosed, school-aged asthmatic children were investigated.

METHODS

The study included parental interviews, physical examination, skin prick tests, lung function studies, including a brief visual interpretation of the flow-volume curve, and a 6-min exercise challenge test on a treadmill, which was used as a reference.

RESULTS

Baseline lung function studies showed a concave-shaped flow-volume curve in 40 (43%) patients, reduced maximal mid-expiratory flow (MMEF) in 25 (27%) and a reduced ratio of forced expiratory volume in 1 s to forced vital capacity (FEV(1)/FVC) in 14 (15%). The drop in peak expiratory flow (PEF) after exercise ranged from 0 to 79% of the baseline (mean 21.3%) and exceeded 12.5% in 52 (55%) patients. There was a small but significant correlation between the baseline FEV(1)/FVC and MMEF values and the response to exercise (r=-0.39 and -0.35; p=0.000, respectively), but when studied by linear regression analysis, the response to exercise was best predicted by the past symptom rate and a concave pattern in the pre-test maximal expiratory flow-volume curve. The values of traditional lung function tests or age, atopy, duration of symptoms or history of exercise-induced wheezing did not remain in the model.

CONCLUSIONS

These results show that the severity of asthma in school-aged children can be predicted at the first visit based on the past rate of symptoms and a visual interpretation of the maximal expiratory flow-volume curve.

Validation of a Dutch language screening instrument for 5-year-old preterm infants

AIM

The validation of the Dutch Taal Screenings Test (TST), a language-screening test, which is included in a follow-up instrument developed to enable paediatricians to assess 5-y-old preterm infants for their motor, cognitive and speech and language development.

METHODS

The speech and language development of 145 5-y-old infants born before 32 wk of gestation and/or with a birth weight of less than 1500 g was assessed by a paediatrician using the TST and by a speech therapist using standardized language tests.

RESULTS

All correlations between the instruments were significant. Using the original cut-off point of the TST for abnormal speech and language development (18 points), the paediatrician will only identify 62% of the children who need speech therapy. For this group of children, a cut-off point of 17 is more effective. The positive predictive value of the TST improved from 77% to 82% by using a parent and school questionnaire to evaluate in a more subjective way the speech and language development.

CONCLUSION

Using the TST, paediatricians will be able to identify speech or language problems in 5-y-old preterm infants.

Determinants of the severity of exercise-induced bronchoconstriction in patients with asthma

AIM

In examining the mechanisms of exercise-induced bronchoconstriction (EIB), it is important to determine which factors most strongly affect the severity of EIB. We determined such factors in patients with asthma by stepwise multiple-regression analysis.

METHODS

Twenty-three patients with asthma underwent pulmonary function tests, methacholine provocation test, and sputum induction. Eosinophilic inflammatory indices and airway vascular permeability index (ratio of albumin concentrations in induced sputum and serum) were examined in sputum samples, and then an exercise test was performed by all asthmatics.

RESULTS

There was a significant correlation between the severity of EIB and degree of eosinophilic inflammation in induced sputum. Moreover, there was a significant correlation between the severity of EIB and airway vascular permeability index. Although we could not find a significant correlation between the severity of EIB and 1-sec forced expired volume, 20% provocation concentration of (PC20) methacholine tended to be correlated with the severity of EIB. By stepwise multiple-regression analysis, we also found that airway vascular permeability index, eosinophil cationic protein levels in sputum, and PC20 methacholine are independent predictors of the severity of EIB.

CONCLUSION

We found that airway vascular hyperpermeability, eosinophilic inflammation, and bronchial hyperreactivity are independent factors predicting the severity of EIB.

Exercise-induced bronchospasm in children: effects of asthma severity

The prevalence of exercise-induced bronchospasm (EIB) in asthmatic individuals has been reported to vary from 40% to 90%. There are, however, few studies addressing the effects of asthma severity on airway responsiveness to exercise. The purpose of the present study was to investigate the effects of asthma severity on EIB in children. We studied 164 children classified as having intermittent (n = 63), mild persistent (n = 30), moderate persistent (n = 40), and severe persistent asthma (n = 31) according to the Global Initiative for Asthma classification. Subjects exercised for 6 min on a cycle ergometer at 80% of their maximum heart rate, and spirometry was performed before and 5, 10, and 20 min after exercise challenge. The prevalence of EIB in children with moderate or severe persistent asthma was significantly greater than in children with intermittent asthma (p < 0.001). EIB-positive children with intermittent asthma exhibited smaller changes in FEV1 than children in the other three groups (p < 0.001). There was no significant relationship between baseline FEV1 and the decline in FEV1 after exercise. We conclude that the prevalence of EIB is greater in children with more severe asthma, and that the intensity of response to exercise is not consistently related to the clinical severity of asthma.

Spirometry, bronchodilator test or symptom scoring for the assessment of childhood asthma

The value of spirometry, the bronchodilator test and 2 weeks' symptom scoring for the assessment of the severity of childhood asthma was studied in a series of 65 consecutively referred school-aged asthmatic children, with the diurnal peak expiratory flow (PEF) variability in home recordings serving as a golden standard. The amplitude of the peak expiratory flow rate (PEFR) variation could be best predicted by the baseline forced expiratory volume in 1 s (FEV1) and the past history of the symptom rate, the correlation with FEV1 being -0.48, p < 0.001. Although the baseline forced expiratory flow between 25 and 75% of the forced vital capacity (FEF25-75%) and the responses of FEV1 and FEF25-75% to salbutamol also showed significant correlations with the diurnal PEFR variability (r = -0.43, r = 0.47 and 0.41, p < 0.001, respectively), these variants did not improve the regression model. The baseline FEV1. FEF25-75% and PEFR and their responses to salbutamol also had a slight but statistically significant correlation with the methacholine threshold, but the symptom score on the diary card did not show comparable correlations with either the diurnal PEFR variability or the methacholine threshold (r = 0.09, NS, and r = 0.05, NS, respectively). These results indicate that both baseline lung function and the response to the bronchodilator test correlate with the severity of childhood asthma more appropriately than does the symptom score on a diary card. Since many of these correlations were rather weak, however, the assessment of the severity of childhood asthma cannot be reliably based solely on spirometry in all patients.

Exercise testing revisited. The response to exercise in normal and atopic children

BACKGROUND

Wide differing criteria are used to define the normal airway response to exercise, and as a consequence the estimated incidence of exercise-induced bronchospasm (EIB) in atopic children is wide. The purpose of this study was to establish normal range for changes in spirometry after exercise in children and then to use these normal values to assess the incidence of EIB in atopic children.

METHODS

Pulmonary function was assessed before, and 2, 5, and 10 min after 6 min of free running exercise in a group of 48 normal and 96 atopic children (70 asthmatics, 17 with allergic rhinitis, and 9 with atopic dermatitis/food hypersensitivity).

RESULTS

The EIB (defined as the normal group mean value -2 SD) occurred with a > 10 percent fall in FEV1, > 17.5 percent fall in peak expiratory flow rate (PEFR), > 26 percent fall in mean forced expiratory flow during the middle half of the forced vital capacity (FEF25-75), and > 40 percent fall in FEF25. Sixty-three of 70 asthmatic patients had EIB by at least one of these definitions, most marked at 5 min postexercise. The combination of FEV1 and FEF25-75 criteria enabled detection of all subjects with EIB. By FEV1 and FEF25-75 criteria, none of the subjects with allergic rhinitis or dermatitis had EIB. The fall in FEV1 after exercise in children with allergic rhinitis was within the range of normal, but with a significantly lower mean value than control subjects.

CONCLUSIONS

EIB should be defined by using more than one maximum expiratory flow-volume curve parameter (ie, FEV1 and FEF25-75). The EIB (defined as a fall in FEV1 and FEF25-75) was only seen in asthmatic children and not in other atopic groups.