Prospective, randomized trial of epinephrine, metaproterenol, and both in the prehospital treatment of asthma in the adult patient.

STUDY OBJECTIVE

To compare the effectiveness and incidence of adverse reactions with three treatment regimens for asthma in adults in the prehospital setting.

DESIGN

Prospective, randomized clinical study.

SETTING

Inner-city emergency medical service system providing basic and advanced life support and transport to 14 urban area hospital emergency departments.

PARTICIPANTS

One hundred fifty-four adult asthmatic patients, 18 to 50 years old, who presented to paramedics with shortness of breath and wheezing.

RESULTS

Eligible patients were randomly assigned by the base station physician to one of three treatment groups: subcutaneous epinephrine, nebulized metaproterenol, or subcutaneous epinephrine and nebulized metaproterenol. Peak expiratory flow rate (PEFR), blood pressure, heart rate, and respiratory rate were measured before and after treatment in each patient. During a 9-month period (October 1992 through June 1993), 154 patients were enrolled in the study; 53 (34%) received epinephrine, 49 (32%) received metaproterenol, and 52 (34%) received both. There were no significant differences in patient demographics, initial vital signs, or pretreatment PEFR among the three groups. The mean difference between pretreatment and posttreatment PEFR was 73 L/min and did not significantly differ among the treatment groups. Significant changes in vital signs were seen in no treatment group.

CONCLUSION

Nebulized metaproterenol is as effective as subcutaneous epinephrine in the prehospital treatment of adult patients with acute asthma. The combination of these two treatments offered no additional clinical benefit in the patients we studied.