RESUMO
The purpose of this study was to evaluate the efficacy of different doses of intravenous magnesium [IV Mg] versus aminophylline therapy for controlling moderate and severe bronchial asthma exacerbations in children who were poor responders to nebulized beta[2] adrenergic agonists. Forty five asthmatic children aged 6 to 15 years with a mean 9.4 +/- 3.7 years were studied and fifteen healthy children of matched age and sex were chosen as controls. The enrolled patients in the study were those whose forced expiratory volume at one second [FEV[1]] remained less than 60% of normal value 30 minutes after the end of three nebulized doses of salbutamol and IV dexamethazone. These patients were randomly assigned into three groups each included 15 patients to receive either magnesium sulphate 25 mg/kg over 30 minutes [group I], 40 mg /kg over 30 minutes [group II] or IV aminophylline infusion 5 mg/kg over 30 minutes [group III]. Vital signs, O[2] saturation [SaO[2]%] by pulse oximetry, FEV[1] and physical examination were serially recorded for 120 minutes. Serum magnesium and aminophylline levels were measured before the start of infusion and 1/2 hourly thereafter for two hours. The mean base line serum levels of Mg in asthmatic groups were lower but not significantly different from that of the controls. There was significant improvement of FEV[1] and SaO[2]% in patients who received IV Mg 25 mg/Kg or 40 mg/Kg with no intergroup differences. However, in comparison with the patients who received aminophylline, those who received magnesium sulphate improved significantly. No significant correlations were detected between FEV[1] and base line serum Mg, but there was positive correlation after 60 minutes IV Mg infusion in groups I and II. No complications were detected in asthmatic children during or after IV Mg therapy. These findings show that IV Mg therapy may be used as an adjunct to classic beta[2] agonists and corticosteroid therapy in the treatment of moderate and severe bronchial asthma exacerbations. The efficacy of high dose IV Mg infusion [40 mg/kg] was not significantly different from that of low dose [25 mg/kg] for controlling moderate to severe asthma exacerbation in poor responder children to beta[2] agonist. Magnesium sulphate may have a role in helping the asthmatic child for whom other conventional therapy failed during the moderate to severe acute attack of asthma