Reduced Peak Inspiratory Effort through the Diskus((R)) and the Turbuhaler((R)) due to Mishandling is Common in...

A minimum peak inspiratory flow (PIF) through dry powder inhalers (DPIs) is required for effective drug delivery to the lungs. Some patients are unable to generate the minimally effective PIF through the DPI. However, little information is available about the 'real life' prevalence of reduced peak inspiratory effort through the Diskus((R)) and the Turbuhaler((R)) as a result of mishandling

We investigated peak inhalation effort through the Diskus((R)) and the Turbuhaler((R)) by both direct observation and the In-Check Dial((R)), a portable PIF meter, in a large sample of patients consecutively referred to our laboratory who were familiar with these devices. Patients with reduced peak inspiratory effort repeated the PIF measurement after a session of instruction on the need for more forceful effort through the device.

We studied 644 patients (mean age 62 years, 42% female). Of these, 62% had chronic obstructive pulmonary disease and 35% had asthma. The mean baseline forced expiratory volume in 1 second was 53% of predicted. 502 patients were using the Diskus((R)) and 185 the Turbuhaler((R)). Overall, 106 patients (16.5%) showed weak inhalation by direct observation at baseline. Of 44 subjects with weak inhalation through the Turbuhaler((R)), 34 (77%) demonstrated a PIF <30 L/min. Post-counselling, only four patients did not achieve a PIF of at least 30 L/min (p < 0.01). Of 62 subjects with weak inhalation through the Diskus((R)), 37 (60%) had a PIF <30 L/min. Post-counselling, all these subjects achieved a PIF of at least 30 L/min (p < 0.001).

A significant number of patients show a reduced peak inspiratory effort through the Diskus((R)) and the Turbuhaler((R)) in real life. Our results indicate that the cause of this deficiency is often mishandling of the device because, after a brief session of instruction on the need for more forceful inhalation, most patients obtained an acceptable PIF rate. A PIF meter may identify patients with inadequately weak inhalation and offer useful feedback for obtaining the best inspiratory effort.