Inspiratory flow rates at different levels of resistance in elderly COPD patients

¹ Respiratory Division, University Hospital Katholieke Universiteit Leuven, Belgium
² Respiratory Division, University Hospital Katholieke Universiteit Leuven, Belgium; and Respiratory Division, Hospital Sint-Maarten Duffel, Belgium
³ Respiratory Division, Hospital Sint-Maarten Duffel, Belgium

^* To whom correspondence should be addressed. E-mail: wim.janssens{at}uz.kuleuven.ac.be.

	Abstract

Dry powder inhalers (DPI) are increasingly replacing metered dose inhalers (MDI) in elderly COPD patients. Most of the DPIs, however, are dependent on inspiratory flow which is compromised by the ageing process itself. With the In-check DIAL method, we compared peak inspiratory flow rates (PIF) in elderly COPD patients (n=26) and matched control subjects (n=14) at a preset resistance level of the Aeroliser, the Diskus and the Turbuhaler. It was found that the PIF measured by the in-check method positively correlated with the PIF derived from spirometry, forced vital capacity and maximal inspiratory pressure, whilst a negative but significant correlation was observed with age. PIF derived from spirometry and age were independent variables which determined PIF across the device, whereas the presence or absence of COPD was not related. When comparing elderly COPD patients with matched elderly controls no difference could be found in PIFs at the different resistances. However, an important number of patients did not reach the recommended flow rate, especially when using the Turbuhaler (30%). In conclusion, this study demonstrates that in elderly patients the ability to generate sufficient inspiratory flow across a DPI is compromised, irrespective of the presence of COPD.