EFFECT OF HIGH-DOSE SALBUTAMOL ON CARDIAC-RHYTHM IN SEVERE CHRONIC AIR-FLOW OBSTRUCTION - A CONTROLLED-STUDY

Despite concern over possible adverse cardiac effects of high-dose bet a-agonists there have been no controlled studies of the effects of suc h a therapy in patients with severe chronic airflow obstruction (CAO). We therefore studied 22 CAO patients (FEV < 1 litre) with continuous ambulatory cardiac monitoring. Patients received either nebulised salb utamol (5 mg) or saline each given 4 times daily for 24 h on 2 consecu tive days, single blind, in random order. Supraventricular arrhythmias were common on both saline and salbutamol days (8 vs. 9 patients, p = NS), but none were clinically apparent. There were no episodes of ven tricular tachycardia. Ventricular ectopic activity was highly variable but did not significantly differ between the two study days overall o r between specific periods after nebulised salbutamol or saline. Serum potassium (mean) fell by 0.23 (SD 0.06) mmol/l in 10 patients after s albutamol. Baseline FEV(1), PaO2, PCO2 were not predictive of arrhythm ias or ectopic activity. While occasional adverse effects cannot be ex cluded, we conclude that high-dose salbutamol does not lead to any gen eral increase in arrhythmogenic potential in severe CAO.