Peak inspiratory flow through Turbuhaler in chronic obstructive airways disease

Many patients with chronic obstructive airways disease (COAD) receive therapy by the inhaled route. This study was performed to assess whether patients with severe COAD could generate sufficient peak inspiratory flow (PIF) through Turbuhaler (Astra, Sodertalje) to operate it effectively. One hundred patients (45 men, 55 women, mean age 69.1 years) with COAD (mean (SD) duration 17.7 (16.3) years) and peak expiratory flow (PEF) < or = 200 l min-1 or forced expiratory volume in 1 sec (FEV1) < or = 1 litre were studied. A series of randomly assigned inspiratory and expiratory lung function tests were contiguously performed, using portable spirometers, within 48 h of a screening visit. An empty Turbuhaler was used in the study. The patients' normal medication was not restricted. Sixty-six patients were previous smokers, eight occasional smokers, 19 habitual smokers and seven had never smoked. Mean (SD) FEV1 was 0.7 (0.2) 1 and mean PEF was 182 (68) l min-1. All patients were able to generate PIF through Turbuhaler (PIF-T) of 28 l min-1 (mean 53; range 28-78 l min-1). Eighty-three patients generated PIF-T of > or = 40 l min-1. PIF-T correlated with PIF without Turbuhaler (r = 0.35), PEF (r = 0.3), FEV1 (r = 0.2) and forced vital capacity (FVC) (r = 0.23) although the relationships were too weak to be used to predict PIF-T. The results suggest that patients with severely limited lung function caused by COAD can operate Turbuhaler effectively.