Effectiveness of delivering moisture to patients’ upper airways via the Wright Mask System

TSZ YAN LING (1), David Y. H. Pui (1) Joshua Oye (2) , Julie Toscano (2)

(1) Particle Technology Laboratory, Department of Mechanical Engineering, University of Minnesota (2) Respiratory Care program, Saint Paul College

     Abstract Number: 488
     Last modified: May 13, 2010

Abstract
Application of aerosol face masks and tracheostomy masks for delivering humidification to patients’ upper airways is a common practice in respiratory therapy treatment. Traditionally, the face mask and tracheostomy mask are used separately. A recent product, the Wright Mask System, connects the two masks to a nebulizer with a T-shaped tube, aiming to reduce the treatment time. The objective of this work is to compare the Wright System and the traditional face and tracheostomy masks in terms of their effectiveness to deliver moisture to the patients’ upper airways.

The average relative humidity (RH) of air from the face mask and tracheostomy mask of the Wright System was measured to be 14% and 32%, respectively. On the other hand, traditional aerosol face mask and tracheostomy mask deliver air with averaged RH of 36%. Although the Wright Mask provides high humidification to the tracheostomy site, the humidity to the face mask which moisturizes the nose, mouth and throat, is not equally high.

The mass median particle size (MMPS) of water droplets delivered by the Wright System and traditional therapies was measured to be 5 to 8 micro-meter, within the effective therapeutic ranges for the upper airways. While the MMPS is within the therapeutic range, the T-tube bending of the Wright System size-selects water droplets from the nebulizer. The MMPS measured at the tracheostomy mask and face mask were 5.4 and 7.6 micro-meter, respectively. Results show that both modes of therapy are effective in producing the required particle size for the treatment of the upper airways. Suggestions for redesigning the mask system will be discussed.