Peak Inspiratory Flow Rate in Chronic Obstructive Pulmonary Disease: Implications for Dry Powder Inhalers

Abstract

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the United States with a significant economic burden related to hospital admissions for exacerbations. One of the primary treatment modalities for COPD is medications delivered through breath-actuated dry powdered inhalers (DPIs). For users to successfully receive inhaled medication, they must inhale with enough flow to overcome the internal resistance of the device, leading to deaggregation of the medication powder. Peak inspiratory flow rate (PIFR) is the maximal flow rate obtained during an inspiratory maneuver. PIFR measurement can be impacted by the internal resistance of the device, which varies with device design. Many devices require a PIFR >60 L/min for adequate medication dispersal, while others appear to have adequate drug deaggregation with a PIFR >30 L/min. Studies have shown PIFRs are reduced among females and decrease with age, without a clear correlation between forced expiratory volume in 1 second and PIFR. PIFR can be reduced at the time of COPD exacerbation. Recent data suggest that reduced PIFR may be associated with worse COPD-related symptom burden, increased odds of COPD-related hospital readmissions, and improved responsiveness to nebulized therapy. This review article aims to examine the physiology and clinical correlations of PIFR, as well as review published studies related to PIFR with DPIs used to treat COPD.

Economic impact and chronic obstructive pulmonary disease outcomes of a comprehensive inhaler to nebulization therapy protocol implementation in a large multi-state healthcare system

“…The other issue that confounds this is the fact that suboptimal PIFRs have been linked to COPD all-cause readmissions 13 . The prevalence of low PIFRs at discharge has been reported to be as high as 33%, so more attention to device selection may be prudent as well 12,14,15 . Any concern for the occasional individual patient desire to have an inhaler while admitted can be addressed through home medication use policies and procedures that should already be in place since US hospitals cannot carry every FDA-approved drug on the US market across pharmacologic classes.…”

“…Due to the significant number of inhalers on the market which require various techniques and skill sets, it is also recognized that inhalers are often not administered correctly in acute care settings 10,11 . There is also increasing evidence that many hospitalized patients may have inadequate peak inspiratory flow rates (PIFRs) to appropriately use the inhalers they have been prescribed [12][13][14][15] . As a result, it is likely worthwhile to assess function before indiscriminately prescribing expensive inhalers, especially in AECOPD.…”

Inhaler devices in asthma and COPD patients – A prospective cross-sectional study on inhaler preferences and error rates

“…The primary bene t of DPIs, when compared with pMDIs and soft mist inhalers, is medication delivery through breath actuation, therefore decreasing issues related to patient synchrony. However, optimal peak inspiratory conditions are required to actuate the device as well as properly deliver the medication [36].…”

Aerosol Delivery Devices for Obstructive Lung Diseases

“…DPIs derive the energy for drug delivery by the patient's inspiratory effort, which is greater than that required for a medication administered as a liquid aerosol. 35,36 Kingdom]). To produce the optimal MMAD, the drug and excipient agglomerate must be de-aggregated during a forceful inhalation against the internal resistance of the inhaler.…”

“…To produce the optimal MMAD, the drug and excipient agglomerate must be de-aggregated during a forceful inhalation against the internal resistance of the inhaler. 35,36 The inspiratory effort required to adequately deliver medication varies among DPIs. Some require more effort than others, and some are more susceptible to variations in flow than others.…”