Some face masks commonly used to help young children inhale asthma medicine are not effective, according to a new study by researchers from Wake Forest University School of Medicine. The results are reported in the current issue of Respiratory Care.
"With some masks, the amount of medicine available to the youngest children is severely decreased because of mask size, stiffness, and poor fit on the face," said Bruce Rubin, M.D., a professor of pediatrics. Rubin is a pediatric pulmonary specialist, a professor of biomedical engineering in the Wake Forest-Virginia Tech Biomedical Engineering & Sciences, and an aerosol scientist.
The researchers studied seven masks used in combination with pressurized metered-dose inhalers to deliver asthma medicine to children. The medication goes into a chamber attached to the mask and is then inhaled by the child. When the mask is placed on the child's face, some air still remains in the mask, which is called dead space volume.
The researchers found that some masks don't fit well or have too much dead space volume. "Dead space volume in the mask contains drug that doesn't get into the lung with each breath," said Rubin.
The seven masks evaluated were those used with the Aerochamber, Optichamber, Easivent, BreatheRite, Ace, Pocket Chamber and Vortex inhalers. The investigators measured mask volume by filling them with water after sealing the outlet end. Then, using an infant-sized mannequin head that is used to teach cardiopulmonary resuscitation, they measured the dead space volume of the masks.
This was done by placing the water-filled mask on a device that measures applied force and pushing the mannequin face into it with a controlled force of 1.5, 3, or 7 pounds to match the range of forces used by parents when applying the mask. The face displaced water from the masks. With masks that fit better on the face and were flexible, more water was pushed out at each force and less remained in the mask as dead space volume.
The researchers also measured how well the mask fit on the face by analyzing digital photographs to determine if there was any leak.