Validation of a numerical model for the mechanical behavior of a continuous positive airway pressure mask

Abstract

Finite Element models (FEM) are developed for the analysis of the contact pressures exerted by a Continuous Positive Airway Pressure (CPAP) mask applied to a dummy head. This is seen as a preliminary step in the analysis of the mechanical effects of CPAP masks applied to human faces, such as recently employed for the care of COVID-19 patients, or other purposes. These mechanical effects can range from negligible, in the case of correct positioning, sufficiently light tension in the headgear, correct mask design, etc., to the possible development of device-related pressure ulcers and/or dentofacial deformations, especially in children. The results of Finite Element analyses are compared, for their validation, with experimental ones. The numerical analysis tool appears able to predict, at an acceptable cost, both the intensity and the area distribution of the contact pressures, as well as the force-displacement relationship occurring in the headgear. This might help the design and the production of more effective and tolerable CPAP masks.

Keywords:

• Finite element analyses
• unilateral contact
• contact pressures

Acknowledgments

The help of Prof. C. Paganelli and Dr. L. Svanetti, of the Dental School, University of Brescia, Italy, during the experimental part of this work is gratefully acknowledged. The kind help of Prof. Giorgio Vassena and coworkers at Gexcel, Brescia, Italy, in the processing of the mask geometry, is acknowledged. The financial support of both the University of Brescia and the Italian Ministry of Teaching and Research (MIUR) is also acknowledged. The FEM code ABAQUS was run at the Department of Civil Engineering of the University of Brescia, Italy, under an academic license. The inter-departmental ‘Laboratorio di Fisiologia Clinica Integrativa’ of the University of Brescia is acknowledged for the technologies used for measuring the contact pressures.

Table 2. Experimental vs numerical contact pressures and areas for the headgear loading case.