 There is a common misconception that patients with asthma cannot master high-resistance dry powder inhalers. A recent study suggests otherwise. Researchers examined 994 consecutive adult patients in the UK during general practice asthma review, approximately 90% of whom already used a preventer inhaler. The team systematically examined the peak inspiratory flow rate, PIFR, needed for successful drug inhalation via inhalers of different device-specific resistances. Each patient's PIFR was measured using the N-check dial meter. The study nurses had extensive experience in conducting asthma reviews and were trained collectively to standardize and optimize their use of the N-check dial meter. Patients were tested at two or three levels of resistance. At the level of their personal preventer inhaler, if they used one, at an R5 level corresponding to high-resistance dry powder inhalers, DPIs, and at a low R0 level corresponding to the resistance of pressurized metered dose inhalers, PMDIs. At each resistance setting tested, patients were instructed to breathe out to comfortable exhalation before performing up to three inhalation maneuvers. If the patient passed, this result was recorded. A pass was defined as an N-check dial reading of 30 to 90 liters per minute at settings R1 to R5 or 20 to 60 liters per minute at the R0 setting based on published standards. Regardless of their current device and with the same level of training provided, more than 93% of patients with asthma achieved the PIFR required to operate a high-resistance DPI. In contrast, approximately 30% of patients failed to achieve the PIFR required to operate a PMDI, including a fifth of patients currently using a PMDI. Patients failing the PMDI setting inhaled too fast. Rapid inhalation with PMDIs is associated with poorer delivery of medicine to the lungs. This study demonstrates that most adult patients with asthma can achieve adequate inspiratory flow to successfully use high-resistance DPIs. However, nearly 20% of patients who currently used a PMDI device failed at R0, even after three assessments with coaching.