Airflow resistance of airflow-regulating devices described by independent coefficients

Rehabilitation after laryngectomy includes more and more the use of airflow -regulating devices such as shunt valves (SVs). tracheostoma valves (TSVs), and heat and moisture exchange (HME) filters. In determining the quality o f those devices, airflow resistance is a very important factor. It is curre ntly defined as pressure drop divided by airflow. However, for most applica tions, this definition does not result in a pressure- and airflow-independe nt parameter. Therefore, a new set of parameters is defined and applied to pressure-airflow curves of airflow-regulating devices. Pressure drop over T SVs and HME filters appears to have a squared relationship with flow. In SV s, it has a linear relationship. The new set of parameters describes the pr essure-airflow relationship properly for all considered devices. In conclus ion, theoretical predictions of flow mechanics appear to be valid for SVs, TSVs, and HME filters. Only 2 coefficients are necessary to describe the pr essure-flow characteristics of these airflow-regulating devices, independen t of pressure drop over and flow through the device.