RESPONSE TO NEBULIZED IPRATROPIUM BROMIDE AND TERBUTALINE IN ACUTE SEVERE ASTHMA

Outpatient studies on asthmatics have shown that inhaled anti-cholinergic agents decrease in efficacy as FEV1 falls. To determine whether there are changes in response to inhaled anti- cholinergics during acute broncho-constriction we have examined the effects of nebulized ipratropium and terbutaline in nine hospitalized patients recovering from acute severe asthma. At 6 a.m. each day throughout the admission, baseline PEFR was recorded. Ipratropium bromide, 1 mg, was nebulized and PEFR measured again 1 h later. Following this, terbutaline, 5 mg, was nebulized with further measurement of PEFR 15 min after nebulization. Results were analysed by paired t- tests. Mean baseline PEFR rose from 1571 m−1 on patients worst day to 3001 m−1 on their best day (P < 0.01). Ipratropium improved mean PEFR by 551 m-1 and 421 m−1 on patients worst and best days respectively (P < 0.01). Subsequent terbutaline improved mean PEFR on patients worst day by 231m-1 (P < 0.01) but only by a non-significant 41 m −1 on their best day (P=0.09). Hence, ipratropium produced 96% of total bronchodilatation when baseline was highest, but achieved only 71% of total response when baseline was lowest, a highly significant change in response (P<0.01). We conclude that in acute severe asthma as baseline PEFR rises response to inhaled ipratropium improves, compared with total response to combined ipratropium followed by terbutaline. © 1992, Baillière Tindall All rights reserved. All rights reserved.