[Peak inspiratory flow during a diskhaler use in subjects unfamiliar with dry powder devices]

Dry power steroid was firstly introduced in Japan in 1998. We measured peak inspiratory flow (PIF) through a Diskhaler in the following groups: well-trained medical representative (EX group, n = 5), respiratory physicians (RP group, n = 19) and non-medical staffs (NM group, n = 31) who were not familiar with Diskhaler, and asthmatic patients who had been briefly trained by a video movie (TP group, n = 93). When PIF was less than 50 l/m dry powders were frequently remained in the brister. The mean PIF in the EX group was 96.1 +/- 12.6 l/m (mean +/- SD). Since the relationship between the PIF and airway pressure (Paw) during Diskhaler use was expressed as PIF = 16.3 square root of Paw-1.19 (r = 0.97), we calculated PIF from Paw measured by a handy barometer made by ourselves. The mean PIF in RP group was 77.0 +/- 30.1 l/m, and 36.8% of the subjects developed inappropriate PIF (i.e., above 100 l/m or below 50 l/m). In NM group the mean PIF was 53.5 +/- 20.4 l/m which was significantly higher than RP group. In this group 54.8% of the subjects yielded inappropriate PIF. The mean PIF in TP group was 64.9 +/- 24.5 l/m which was significantly lower than that in RP group. Those who developed inappropriate PIF occupied 43.2% of the RP subjects. We concluded that a quantitative presentation of PIF in mandatory to achieve an effective use of Diskhaler.