Breathlessness and exercise tolerance in chronic airflow obstruction: 2-hourly versus 4-hourly salbutamol by inhalation.

Breathlessness, exercise tolerance, and spirometry were measured in 12 patients whose major symptom was breathlessness, secondary to severe chronic airflow limitation, during a double-blind crossover comparison of inhaled salbutamol in two dosages (200 micrograms 4-hourly and 200 micrograms 2-hourly) with placebo. Daily visual analogue scores of breathlessness, exercise tolerance and spirometry were all significantly improved with salbutamol in both dosages compared to placebo. The 2-hourly regimen was superior to the 4-hourly regimen only in terms of exercise tolerance. Walking distance had deteriorated significantly 2 hours after salbutamol on the 4-hourly regimen and was usefully increased by an extra dose of salbutamol on the 2-hourly regimen at the equivalent time, without side-effects. Salbutamol provided considerable symptomatic relief in addition to spirometric improvement in patients with chronic airflow limitation.