High dose salbutamol in chronic airflow obstruction: comparison of nebulizer with Rotacaps.

Patients with severe chronic airways obstruction often respond poorly to inhaled salbutamol in conventional dosage from a pressurized aerosol. We have investigated the response to high dose salbutamol in 18 patients with chronic airways obstruction (mean age 64.4 years, mean FEV1 40.2% predicted, less than 15% response to 400 micrograms salbutamol). Patients were given 1 mg, 2 mg and 5 mg of salbutamol by either Rotacaps or nebulizer in random order on separate days. Response was measured over 8 h as a change in airway calibre (FEV1, FVC and PEF). The frequency of tremor, palpitations and arrhythmias was noted. Area under the curve for change from baseline values for FEV1, FVC and PEF showed that larger doses of salbutamol (nebulized or Rotacaps) result in larger areas from all three variables. Analysis of peak response, for FEV1, FVC and PEF showed no significant difference for the six treatments used except that the peak response for 2 mg Rotacaps for FEV1 was significantly larger than that for 1 mg Rotacaps (P less than 0.05). The results of this study show that in severe chronic airflow obstruction 1, 2 and 5 mg of salbutamol inhaled via a rotahaler device are just as effective as 1, 2 and 5 mg salbutamol inhaled from a nebulizer in producing bronchodilation. High dose salbutamol is well tolerated and side effects are minimal. Rotacaps have the advantage of being more portable than a wet nebulizer.