The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

HOLDING CHAMBERS DELIVER MORE AEROSOL THAN MDI AND SPACERS WITH RANDOM ACTUATIONS

James B. Fink, MS, RRT, Greg Ligman, RCP, Hines VA Hospital, Loyola Stritch School of Medicine, and Triton College Respiratory Care Program, Hines, IL

Background: Aerosol delivery from a metered dose inhaler (MDI) is reduced when actuation is not synchronized with inspiration. Spacers and holding chambers are prescribed to protect patients from loss of dose secondary to asynchrony, but their relative merits have not been well established.

Method: Five puffs of albuterol (90µg/puff) were administered from a MDI alone, chamber spacer (toilet paper roll), small volume spacer (Optihaler) and valved holding chamber (Aerochamber) into a lung model (AJRCCM 1998: 157:A636) simulating spontaneous ventilation (V_{T} 500, f 50 bpm, PIF 80 L/min). The MDI was actuated at the beginning of inspiration (SYNCH) and at 30 sec intervals independent of respiratory cycle (RANDOM). Aerosol was collected on a filter distal to a USP "throat", analyzed by spectrophotometry and reported as µg of albuterol with standard error bars. ANOVA, p < 0.05 is significant.

Results: During SYNCH, the small volume spacer delivered less aerosol than all other devices (p < 0.01). RANDOM actuation delivered less drug than SYNCH for the MDI alone and both spacers (p < 0.02). With RANDOM actuation, the valved holding chamber delivered more drug than the other devices (p < 0.01), and comparable drug as the MDI alone during synchronized actuation (p=0.36).

(See original for figure)

Conclusion: When synchrony of MDI with inspiration is unreliable, the valved holding chamber protects from loss of drug dose.

The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.

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