The impact of inspiratory effort on inspiratory flow through Turbuhaler® in asthmatic patients

Abstract

To investigate the impact of the inhalation effort on the peak inspiratory flow through Turbuhaler®, 100 asthmatics having a wide range of asthma severity (baseline forced expiratory volume in one second 28-127% of predicted normal) were studied. Each patient inhaled through four modifications of empty Turbuhaler inhalers, using first a 'deep' inhalation and then a 'forceful and deep' inhalation manoeuvre. Peak inspiratory flow increased by an average of 20% using a 'forceful and deep' as compared to a 'deep' inhalation, with a markedly higher increase for the patients who had a low peak inspiratory flow using the deep inhalation. Virtually all patients (97-100%) attained a peak inspiratory flow ≤ 40 L·min-1 after a 'forceful and deep' inhalation. This study demonstrates that instructing the patient to take a 'forceful and deep' inhalation optimizes the use of Turbuhaler®. Irrespective of asthma severity, the vast majority of patients could attain a sufficiently high peak inspiratory flow with a 'forceful and deep' inhalation.