High inhaler resistance does not limit successful inspiratory maneuver among patients with asthma or COPD

Figures & data

Figure 1. Schematic representation of inhaler-patient system.

Figure 2. Flow rate is accelerated for the formulation dispersion by orifice in the standard Easyhaler DPI as shown by computational fluid dynamics simulation.

Table 1. Resistances, flow requirements, and In-Check Dial resistance levels for various commercial inhalers [25,27–30,34].

Inhaler	Resistance ($\sqrt{\mathrm{k}\mathrm{P}\mathrm{a}}\mathrm{m}\mathrm{i}\mathrm{n}/\mathrm{L}$)	Optimal flow requirement [28] (L/min)	In-Check Dial† resistance level	Inhaling instructions**
Breezehaler	0.017	50	R1	Breathe in quickly and as deeply as you can. During inhalation you will hear a whirring noise.
Aerolizer	0.018	65	R1*	Breathe in quickly and deeply – you should hear whirring noise
Ellipta	0.027	60	R2	Take 1 long, steady, deep breath in through your mouth.
Novolizer	0.027	50	R2*	Inhale the powder steadily, deeply and as rapidly as possible (to the maximum inhalation).
Accuhaler/Diskus	0.027	60	R2	Breathe in steadily and deeply through your Diskus
Genuair	0.031	45	R3	Take a strong, deep breath through your mouth.
Turbuhaler Symbicort	0.035	60	R3	Breathe in as deeply and as hard as you can through your mouth.
Spiromax	0.035	40	R3	Breathe in through your mouth as deeply and as hard as you can.
NEXThaler	0.036	35	R4	Take a quick and deep breath in through your mouth.
Easyhaler, center slot	0.036	30	R4	Take a strong and deep breath in.
Turbuhaler Pulmicort	0.039	60	R4	Breathe in as deeply and as hard as you can through your mouth.
Easyhaler, standard	0.044	30	R5	Take a strong and deep breath in.
Handihaler	0.047	30	R5	Breath in deeply until your lungs are full. You should hear or feel the capsule vibrate.

† An inhaler training device with adjustable flow resistance *Not present in the In-Check dial instruction leaflet, but designated by authors based on comparable device resistance. **From the patient instruction leaflet of each inhaler.Breezehaler (Novartis, Basel, Switzerland), Aerolizer (Novartis, Basel, Switzerland), Ellipta (GSK, Brentford, United Kingdoms), Novolizer (Mylan, Hertfordshire, United Kingdoms), Accuhaler/Diskus (GSK, Brentford, United Kingdoms), Genuair (AstraZeneca, Cambridge, United Kingdoms), Turbuhaler (AstraZeneca, Cambridge, United Kingdoms), Spiromax (TEVA, Petah Tikva, Israel), NEXThaler (Chiesi, Parma, Italy), Easyhaler(Orion, Espoo, Finland), Handihaler (Boehringer-Ingelheim, Ingelheim, Germany)Breezehaler (Novartis, Basel, Switzerland), Aerolizer (Novartis, Basel, Switzerland), Ellipta (GSK, Brentford, United Kingdoms), Novolizer (Mylan, Hertfordshire, United Kingdoms), Accuhaler/Diskus (GSK, Brentford, United Kingdoms), Genuair (AstraZeneca, Cambridge, United Kingdoms), Turbuhaler (AstraZeneca, Cambridge, United Kingdoms), Spiromax (TEVA, Petah Tikva, Israel), NEXThaler (Chiesi, Parma, Italy), Easyhaler(Orion, Espoo, Finland), and Handihaler (Boehringer-Ingelheim, Ingelheim, Germany).

Table 2. Percentage of patients who successfully performed the inhalation manoeuvre with flow rate requirements according to Table 2.

Resistance/Inhaler	Fraction of successful patients (%)
R2, Diskus/Ellipta [20,31–33]	56–99
R3	NA*
R4 Turbuhaler [20,33,40]	45–91
R4 Easyhaler centerslot/NEXThaler [20,33,37,38]	97–100
R5 Handihaler [32,37]	68–99
R5 Easyhaler standard [20,36]	94–100
pMDI [36,45]	14–71
pMDI+spacer [45]	81

*High variation in the flow rate requirements makes it impossible to interpret generic data.

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