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Sensitivity of forced expiratory flow between 25% and 75% of the vital capacity (FEF25-75) in detecting airway obstruction was investigated in 14 children with mild-moderate asthma, allergic to house dust mites, while at high altitude (1756 m). Forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), FEF25-75, and peak expiratory flow (PEF) were measured every 2 weeks for 12 weeks (total, 84 measurements). The presence or absence of wheezing at the chest auscultation was ascertained before each test. During the study period, a significant improvement of both mean (SD) FEF25-75 [61 (12)% vs. 68 (11)% of the predicted value, p = 0.005] and PEF [95 (16)% vs. 103 (13)%, p = 0.002] was observed. FEV1 changed only marginally [82 (7)% vs. 86 (6)%, p = 0.05]. Wheezing was present on 12/84 occasions. Wheezing was associated with abnormal FEF25-75 values on most occasions but not with abnormal FEV1 or PEF. FEF25-75 was decreased on 51% of days in which wheezing was absent. FEV1 and PEF were, respectively, normal in 69% (p < 0.0001) and 92% (p < 0.0001) of measurements in which FEF25-75 was abnormal. These results suggest that FEF25-75 may be considered a good indicator of airflow obstruction and a sensitive marker of respiratory improvement in asthmatic children during reduced antigen exposure.

Bronchial hyperresponsiveness (BHR) reflects an exaggerated sensitivity of airways to pharmacologic and/or physical stimuli. Patients with symptomatic asthma often have a higher degree of BHR than nonasthmatics, even though BHR shows a variable relationship with the clinical expression of the disease and with medication requirements. Methods of bronchial challenge, initially developed in adults, are increasingly employed also in children. The Authors discuss the clinical significance of the evaluation of bronchial responsiveness in the diagnostic approach and follow-up of children with asthma. Some methodological aspects and limits of bronchial challenging in childhood are expecially addressed.

Changes of diurnal variation of peak expiratory flow rate (%PEF variation) and their relationship with bronchial hyperresponsiveness (BHR) to methacholine (PC20) were evaluated in 12 children with mild-to-moderate asthma and house-dust mite allergy, during successive periods of stay in a mite-free environment at high altitude (1756 m) and at their home at sea level. The children remained at the high altitude from October until the end of December; then they spent a 3-week period at home and returned to high altitude residence in January. PEF was measured daily, in the morning and in the evening, during the 3 months' stay at high altitude and them for 10 days after the return in January. PC20 was assessed in 8/12 children, once a month from October to December, and at the return in January. Mean absolute PEF values did not change significantly throughout the study. From October to December, patients showed a significant decrease of mean %PEF variation (P = 0.04), while PC20 showed an increase (P = 0.05). After the 3 weeks at home, both %PEF variation (P = 0.03) and PC20 (P = 0.05) significantly worsened. The correlation between PC20 values and mean %PEF variation in the 2 days before and after each methacholine test was r = -0.63 (P = 0.001). Our data suggest that there is a beneficial effect of a prolonged stay in a mite-free environment, on both PEF variability and BHR, also in asthmatic children with good pulmonary function. PEF variability and bronchial responsiveness to methacholine were significantly correlated also for small changes of the two variables.

Several educational programmes have been developed for patients with asthma, in order to promote changes in behaviour and to improve health and quality of life. Such programmes are commonly termed "asthma self-management" programmes. First generation self-management programmes started in the early 1980s and were intended to develop the concept of "partnership" between physician, patient and family, and to teach children the skills necessary to manage asthma at home. As a result of participation in these programmes, children experienced a reduction of emergency room and unscheduled physician visits, and an improvement in their physical and social activities. The need to assess the long-term persistence of self-management skills led to the development of second generation programmes. These programmes will pay more attention to the within-subject assessment of acquisition and application of self-management techniques. Crucial issues, such as decision-making strategies and evaluation of quality of life should also have a prominent role.

Theophylline level variability obtained with standard slow-release theophylline tablets was compared to that obtained with a new sustained-release theophylline suspension in asthmatic children. The sustained-release preparations were administered every 12 hours and serum samples were collected after ten days of treatment during the steady-state period. In this crossover study, the sequence of the two regimens (slow-release tablets versus slow-release suspension) was selected at random. Both preparations of theophylline were administered at a mean dosage (+/- s.d.) of 19.3 +/- 1 mg/kg/day. The results of our study demonstrated that theophylline serum levels remain within the therapeutic range for both preparations, but there was a greater fluctuation with theophylline suspension compared to the tablets. The tolerability of the two drugs was satisfactory.

The effects of high altitude were evaluated in 14 children with allergic bronchial asthma over an 8-month period. Clinical improvement, as assessed by decreased bronchial lability, was demonstrated by pulmonary function studies. There was a decreased requirement for drugs and steroids were discontinued in our children. The results of this study suggest the use of this approach as a possible adjunct to the management of refractory cases of bronchial asthma.

Fifteen asthmatic children were tested in a double-blind fashion. The degree of prevention of exercise-induced asthma by three pharmacological forms of sodium cromoglycate (SCG with lactose powder, SCG in micropellets without lactose and SCG solution) was evaluated. FEV1 and FEF 25-75 were measured. Inhibition of the airway response to exercise was achieved by SCG without any statistical differences between the three active forms. Our data suggest that the new pelletised form of SCG without lactose is as active as the other preparations of the drug. The easy mode of administration allows a high compliance of the young asthmatic patients to chronic therapy.

The applicability and reliability of the clinical usefulness of monitoring salivary theophylline concentrations as a predictive measure of serum concentrations was evaluated in a total of 59 children with asthma, divided in four groups. Three pharmacological preparations of oral theophylline (aqueous, alcoholic and slow release) were evaluated after single administration (groups 1-3); slow release theophylline was also tested in a steady state of metabolism in children under chronic therapy with the drug (group 4). Although a good correlation between theophylline concentrations in serum and saliva was observed in each group, the wide range of variability in serum levels predicted from salivary levels (20-60%) appears to limit the usefulness of this approach. The salivary measurements of theophylline may be useful as a general guide in management of patients, or in assessment of compliance.