Impact of Preliminary Bronchodilator Dose in Chronic Obstructive Pulmonary Disease Patients With Suboptimal Peak...

Suboptimal peak inspiratory flow rate (PIFR) is highly prevalent in patients with chronic obstructive pulmonary disease (COPD) owing to the mismatch of their PIFR with the corresponding inhaler-device resistance. This study aimed to investigate the impact of a preliminary dose of pressurized metered dose inhalers (pMDIs) on patients with COPD with suboptimal PIFR using Diskus dry powder inhalers (DPIs).

A prospective, randomized, case-control study included 24 patients with COPD. PIFR was measured using the In-Check Dial G16 with low-to-medium resistance. Spirodoc was used to measure baseline spirometric data and compare it before and 30 minutes after the administration of Diskus DPI. On a different day, the study dose was given to each suboptimal patient by the same aerosol generator with preceded 2 puffs of salbutamol pMDI and re-evaluated for spirometric parameters 30 minutes after the study dose.

There was a significant difference between the optimal and suboptimal groups in peak expiratory flow (2.38 ± 1.20 vs 1.49 ± 1.06 L/s, P = 0.050). PIFR showed a statistically significant difference between the optimal and suboptimal groups (71.66 ± 6.15 vs 41.25 ± 9.79 L/min, P < 0.0001). There was a significant difference in forced vital capacity (ΔFVC) between optimal and suboptimal groups without a preliminary dose (0.42 ± 0.21 vs 0.16 ± 0.11 L, P = 0.002), forced expiratory volume in 6 seconds (ΔFEV₆) (0.53 ± 0.49 vs 0.17 ± 0.11 L, P = 0.022), forced expiratory volume in 3 seconds (ΔFEV₃) (0.41 ± 0.38 vs 0.1 ± 0.16 L, P = 0.013), forced expiratory volume in 1 second (ΔFEV₁)/FVC (-2.38 ± 8.41 vs 2.96% ± 2.95%, P = 0.033), and ΔFEV₁/FEV₆ (-4.32 ± 11.23 vs 2.91% ± 4.35%, P = 0.015). There was a significant difference in ΔFVC between optimal and suboptimal groups with a preliminary dose (0.42 ± 0.21 vs 0.23 ± 0.18 L, P = 0.046), ΔFEV₁/FVC (-2.38 ± 8.41 vs 5.67% ± 6.53%, P = 0.009), ΔFEV₁/FEV₆ (-4.32 ± 11.23 vs 5.16% ± 4.99%, P = 0.008), and forced expiratory time (ΔFET) (0.28 ± 0.45 vs -0.31 ± 0.70 seconds, P = 0.022). The only parameter that showed a significant difference between suboptimal groups without and with a preliminary dose is Δ peak expiratory flow (0.24 ± 0.59 vs 0.65 ± 0.68 L/s, P = 0.004).

Administering a preliminary dose of pMDI can minimally enhance the effectiveness of DPIs in patients with COPD with suboptimal PIFR and health outcomes.