Expiratory flow measurement
cough, Expiratory airflow
The in-expiratory airflow generated in both directions during the MI-E session was measured using a flowmeter (CITREX H4 gas flow analyzer, IMT Analytics, Buchs, Switzerland) serially connected to one side of a single-use antibacterial filter towards the facemask interface, and the other side to the CoughAssist E70. This flowmeter was formally calibrated and validated annually by IMT Analytics to ensure that the maximal uncertainty error was within 0.75% for all measurements. Expiratory airflow was measured as a negative value; therefore, the lowest value during exsufflation was the PCF, which could be calculated from each cough with continuous airflow measurement