Assessment of tracheal temperature and humidity in laryngectomized individuals and the influence of a heat and moisture exchanger on tracheal climate

Background. The beneficial function of heat and moisture exchangers (HMEs) is undisputed, but knowledge of their effects on intra-airway temperature and humidity is scarce. The aim of this study was to evaluate the clinical applicability of a new airway climate explorer (ACE) and to assess the HME's influence on tracheal climate. Methods. Intratracheal temperature and humidity were measured with and without HME in 10 laryngectomized patients. Results. An HME causes the intratracheal mean humidity minima to increase with 3.2 mg H ₂O/L (95% CI: 1.5-4.8 mg H₂O/L; p <.001), from 21.4 to 24.6 mg H₂O/L, and the mean temperature minima to decrease with 1.6°C (95% CI: 0.9-2.4°C; p <.001) from 28.5°C to 26.9°C. Relative humidity values suggest that the tested HME keeps inspired air (nearly) fully saturated during the full course of inspiration. Conclusion. Assessment of intratracheal temperature and humidity, and evaluation of HME effectiveness is feasible with the ACE. The tested HME significantly increases the intratracheal humidity, but decreases the intratracheal temperature. Relative humidity calculations suggest that increasing the thermal capacity of this rehabilitation device can further increase the heat and moisture exchange efficiency.