Appropriate use of a dry powder inhaler based on inhalation flow pattern

An optimal inhalation flow pattern is essential for effective use of a dry powder inhaler (DPI). We wondered whether DPI instructors inhale from a DPI with an appropriate pattern, and if not, whether self-training with visual feedback is effective.

Subjects were 14 pharmacists regularly engaged in instruction in DPI use. A newly designed handy inhalation flow visualizer (Visual Trainer: VT) was used to assess inhalation profiles and to assist in self-training. With a peak inhalation flow rate (PIFR) > 50 L/min, time reaching PIFR (T_PF) < 0.4 s, inhalation volume (V_I) > 1 L, and flow at 0.3 s after the onset of inhalation (F_0.3) > 50 L/min, the pattern was considered optimal.

Using Diskus or Turbuhaler 12 and 10 subjects respectively inhaled with a suitable PIFR. Those with a satisfactory F_0.3 were 10 and 7 respectively. The T_PF was short enough in only 1 and 2 respectively. All 14 subjects inhaled deeply (V_I) through Diskus, and 10 did so through Turbuhaler. In the self-training session, only 3 subjects satisfied all three variables at the first trial, while 2 or 3 trials were required in other subjects. Among the three variables, optimal T_PF was the most difficult to attain. Once a satisfactory inhalation pattern was achieved using one DPI, eleven out of 12 subjects inhaled with a satisfactory pattern through the other DPI.

Visualization of the inhalation flow pattern facilitates the learning of proper inhalation technique through a DPI.