Utility of peak inspiratory flow measurement for dry powder inhaler use in chronic obstructive pulmonary disease

Purpose of review Every type of dry powder inhaler (DPI) device has its own intrinsic resistance. A patient's inspiratory effort produces a pressure drop that determines the inspiratory flow, depending on the inhaler's specific internal resistance. Optimal peak inspiratory flow (PIF) is needed for effective release of dry powder, disaggregation of drug-carrier agglomerates, and optimal deposition of respirable drug particles, particularly generation of a high fine-particle fraction to reach the small airways of the lungs. However, standardized recommendations for PIF measurements are lacking and instructions appeared vague in many instances. Recent findings Suboptimal PIFs are common in outpatient chronic obstructive pulmonary disease (COPD) patients and during acute exacerbations of COPD, and are associated with increased healthcare resource utilization. There is significant variation in the results of studies which is in part related to different definitions of optimal flow rates, and considerable variation in how PIF is measured in clinical and real-life studies. Summary Standardization of technique will facilitate comparisons among studies. Specific recommendations for PIF measurement have been proposed to standardize the process and better ensure accurate and reliable PIF values in clinical trials and clinical practice. Clinicians can then select and personalize the most appropriate inhaler for their patients and help them achieve the optimal PIF needed for effective drug dispersion.