Yet another cause for blocked sidestream capnogram - Beware of the non-threaded cap mount in heat and moisture exchangers

Heat and moisture exchangers (HME) are commonly used during general anaesthesia and intensive care of patients on mechanical ventilators. Some of the HME manufacturers provide HMEs with a Luer lock fitting for connecting side stream CO₂ monitoring line, Luer lock cap, and a non-threaded cap mount. However, HMEs from different manufacturers and HMEs meant for use in children and for adults from the same manufacturer vary in the presence/absence of non-threaded cap mount. This can create confusion to the clinicians and can result in inadvertent connection of the CO₂ monitoring line to the non-threaded cap mount resulting in blocked CO₂ monitoring line and leak in the circuit. We caution all the anaesthesiologists and intensivists regarding this possibility while using HMEs from different manufacturers.