Performances of heated wire humidifiers during adult mechanical ventilation: Estimation of the amount of condensation

Abstract

During invasive artificial ventilation is crucial to heat and to humidify gases delivered to patients. Heated Wire Humidifiers (HWHs) are largely used to perform this task. Their performances are strongly influenced by ventilatory settings (e.g., Minute Volume-MV- and respiratory frequency-f-), and environmental conditions. An important concern in case of over-humidification is the formation of water condensation within the breathing circuit, which increases the risk for pulmonary infection and the occlusion of endotracheal tube. Several studies assessed the water condensation by qualitative scales. This work aims to estimate the mass of condensed vapor within the breathing circuit at different MV and f, covering all the conditions used during adult ventilation. Results show that the condensed vapor increases with both MV and f. Moreover, preliminary experiments show that the condensation decreases with room temperature. The substantial amount of condensation confirms the weaknesses of the control strategy mostly implemented on commercial HWHs. These data can be helpful to figure out the impact of ventilatory settings on HWHs performances and to find out novel solutions to improve them.