Effect of physical position on peak inspiratory flow in stable COPD

Abstract

<b>Background:</b> Peak inspiratory flow (PIF) informs dry powder inhaler (DPI) choice. Little is known about modifiable factors affecting PIF. <b>Aim:</b> To examine the impact of physical position on PIF in stable COPD. <b>Methods:</b> We enrolled individuals with spirometry-confirmed COPD, using DPI, and free of recent exacerbation. For eligibility, participants must have PIF of 30-90 L/min for high resistance (R5, Handihaler^®) and 60-90 L/min for low-medium resistance (R2, Diskus^®, Ellipta^®) DPIs using InCheck Dial^®. PIF was measured in 3 positions at random (standing, sitting upright, supine 45^o with head forward) against prescribed inhaler resistance. For each position, PIF measurement was done in triplicate, with the highest value used for analyses. Paired samples t-test with Bonferroni correction for multiple comparisons was used to compare positional values. <b>Results:</b> To date, 79 participants have been screened, 63 enrolled and 60 underwent positional measurements. Characteristics of the 60 patients were mean age, 64.6 years; male, 45% and mean FEV1, 48% predicted. Overall, 72% were using R2 only, 20% R5 only and 8% both R2 and R5 DPIs. Mean(SD) PIF for standing, sitting and supine were 82.8(14), 80.5(15) and 76.6(15) L/min for R2 and 50.8(10), 48.1(10) and 45.0(8) L/min for R5, respectively. For R2, supine position was significantly lower than sitting or standing (corrected p&lt;0.05). For R5, supine position was significantly lower than standing only (corrected p&lt;0.05). <b>Conclusions:</b> In a stable COPD population, PIF was highest in standing position and lowest in supine position regardless of DPI type. This analysis highlights the importance of physical position during DPI inhalation maneuvers and measuring PIF in COPD patients.