1. Introduction and Background:
Obstructive Sleep Apnea (OSA) is a type of sleep disordered breathing which results in a patient’s upper airway collapsing during sleep. This collapse leads to an obstruction within the airway which wakes the patient. An untreated patient may experience these events hundreds of times a night which can cause, or contribute to heart conditions and chronic fatigue. The simplest, most effective, and most common treatment for OSA is a device called a continuous positive airway pressure device or a CPAP. A CPAP provides a constant pressure source that when connected to a patient through tubing and a mask, will open the airway by keeping the internal pressure of the airway high enough to support the section that would otherwise collapse. Since the CPAP mask covers a patient’s nose and or mouth exhales CO2 must be removed from the mask through an exhaust system. Currently venting or ‘bias’ holes are included in the CPAP masks to create a net flow and flush out adequate amounts of CO2.
One of the challenges in mask design arising from the bias flow include:
• Noise from the mask – the noise level from the mask can cause patient or bed partner annoyance. This is a significant area of research within Fisher and Paykel Healthcare (FPH) to produce more desirable products. Most of the research have followed an iterative process through prototyping and testing physical solutions.
• Draft from the mask – the airflow from the mask can cause patient or bed partner annoyance. The air jet from the bias flow can generate noise when it encounters an object such as a pillow or direct with the patient or bed partner.
Figure 1. Fisher and Paykel Healthcare’s latest range of CPAP masks.
2. Scope:
This project will look at how mask type, exhaust location and design contribute to noise.
Research will need to be a combination of subjective feedback from people wearing masks, physical testing as well as using Computational Fluid Dynamics (CFD) to simulate the use of the different types of masks and to be used to evaluate against physical test results.
3. Resources:
Students undertaking this project will have access to a CPAP machine, a range of FPH OSA masks and where needed supervised access to model shops and labs at FPH.
Undergraduate
Obtained A- or better grade in each of the Mecheng325 and 322 courses.
Enrolled into (or previously completed) the Mecheng712 course.
Thermofluids Lab (Newmarket 901 Lvl 3 , Lab)