Reduction in patient timing errors using a breath-activated metered dose inhaler.

Delivery of aerosol medication to the lower respiratory tract by metered dose inhaler (MDI) is often limited by the patient's inability to properly coordinate activation of the device with inspiration. This study evaluated a new breath-activated MDI device, designed to minimize patient timing errors by sensing inspiratory flow and automatically activating to deliver aerosol medication. Twenty novice adult volunteers, previously naive to the technique of MDI use, and 20 patients currently using MDIs were tested in their ability to coordinate MDI usage. Simultaneous recording of respiratory events and device activation allowed analysis of timing errors. With a conventional MDI, a 31.0 percent incidence of errors was seen in the novice group and a 21.5 percent incidence of errors was seen in the experienced group. These compared with error rates using the breath-activated MDI of 6.5 percent and 5.0 percent in the two groups respectively (p = 0.009, p = 0.04). The breath-activated inhaler was preferred by 35 of 40 subjects. In conclusion, MDI technique timing errors were significantly less with this breath-activated MDI device in both novice and experienced subjects, and it was also preferred by both groups.