Table 1.

Requirements of inspiratory flow and maneuver for using inhalers^{[6, 7, 8, 9, 10]}

Inhalers		Internal resistance levels	Minimal PIFr (L/min)	Optimal PIFr (L/min)	Inhalation maneuvers
pMDIs	Traditional pMDI, Aerosphere®	Nearly no resistance	10	30	Inhale slowly, steadily, and deeply, synchronously actuating the inhaler after initiating inspiration
SMIs	Respimat®	No resistance	10	30	Actuate the inhaler and simultaneously inhale slowly, steadily, and deeply
DPIs	Breezhaler® Accuhaler®/Diskus®, Ellipta® Turbuhaler® (combination)	Low resistance Medium-low resistance Medium resistance	20–50	30–65	Inhale forcefully through the mouth from the very beginning until the lungs are full
	Turbuhaler® (monotherapy), Easyhaler® C (combination)	Medium-high resistance
	HandiHaler®, Easyhaler® M (monotherapy)	High resistance

PIFr: peak inspiratory flow against resistance; pMDIs: pressurized metered-dose inhalers; SMIs: soft mist inhalers; DPIs: dry powder inhalers.