Spacers and Holding Chambers

Ariel Berlinski, MD, FAAP

Introduction

Spacers and valved holding chambers (VHCs) have been developed to overcome several problems with pressurized metered dose inhalers (pMDIs).

• The aerosol emitted by pMDIs travels at high speed.

• High-velocity aerosols are more likely to be deposited in the upper airway by inertial impaction.

•A common error that occurs during inhalation of pMDi aerosols is to inhale too quickly.

•Local side effects of corticosteroids, such as thrush and hoarseness, are caused by oropharyngeal deposition.

•Coordination of actuation of the pMDI and inhalation is difficult to achieve by pediatric patients.

Spacers

•Spacers are valveless tubes that provide a distance between the pMDI and the patient’s mouth.

—Aerosol speed decreases as it travels through the spacer.

—Particle size decreases because of evaporation of the propellant.

—Large particles impact against the airway walls.

—The use of a spacer does not prevent the patient from exhaling inside the tube.

•Commercially available and homemade spacers decrease oropharyngeal deposition.

•A pMDI of flunisolide with an incorporated spacer is available in the United States.

•Spacers should only be used in children who can perform a single- inhalation maneuver.

Valved Holding Chambers