Terbutaline in the Treatment of Acute Asthma in Childhood

AIthough there have been a few studies on the effect of terbutaline in children, none has compared the effect of terbutaline with the effect of epinephrine during the acute asthmatic attack. In a parallel study, we have demonstrated the efficacy of terbutaline in the treatment of status asthmaticus in children. Because those patients by definition were unresponsive to treatment with epinephrine, ethical and practical considerations precluded us from comparing the effects of terbutaline with epinephrine in that study. Therefore, this separate double-blind study was performed, in which the efficacy of terbutaline and epinephrine were compared in acute childhood asthma. In addition, this study enabled us to compare the effects of both drugs on the pulmonary and cardiovascular systems in acute childhood asthma.

Materials and Methods

All patients known to have asthma without coexisting cardiac disease who required treatment with epinephrine for an acute asthmatic attack were eligible for the study. After informed consent was obtained, a total of 48 children ranging in age from 2 to 16 years were given either epinephrine or terbutaline in a random double-blind fashion. The same subcutaneous dose (0.01 mg/kg of body weight, to a maximum of 0.3 mg) and concentration of the drug (1 mg/ml) were used for both drugs. Any patient who failed to show appreciable improvement 30 minutes after the first dose of the drug was given a repeat injection of the same drug at the same dose. Patients were evaluated for the next 30 minutes and were either discharged if sufficiendy improved or were given other forms of therapy. No other treatment was given during the study. All studies were carried out in the setting of die emergency room.

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Terbutaline in children

Clinical assessment of each patient, including measurement of heart rate, respiratory rate, and systemic arterial systolic and diastolic blood pressures, was made before and at 15, 30, and 60 minutes after the administration of the randomly assigned drug. In the group of patients requiring a second dose of drug, the 30-minute assessment was made just before die second injection, while the 60-minute assessment was made 30 minutes after the second injection. When technically feasible, the forced expiratory volume in one second (FEVi) was measured using a water-filled spirometer. Because of die extreme respiratory distress of the patients at the time, it was not possible for most of diem, even when old enough to cooperate, to perform the maneuver to determine FEVi. For this reason, we developed a clinical index based on the extent of wheezing, retractions of the chest, and flaring of the alae nasi, in order to quantitate objectively the severity of obstruction of the airway before and after administration of the drug. Wheezing was graded on a scale from zero to three, as follows: 0, absent; 1, mild; 2, moderate; and 3, severe. Retractions were graded from zero to two on the following scale: 0, absent; 1, mild; and 2, severe. Nasal flaring was graded as either zero (absent) or one (present). Thus, the range of possible scores on the clinical index for obstruction of the airway ranged from zero to six. A score of zero represented no illness, while six represented the most severe illness.