人工鼻フィルター（HMEF）が加湿不足あるいは加湿過剰をきたす換気条件に関する定量的研究

抄録

Heat and moisture exchanger filters (HMEFs) are commonly used in mechanical ventilation practices. We described the performances of HMEF in extreme conditions which may decrease expected moisture returns from HMEF. The experiments with dry gases were performed on the model lung-ventilator system. The test lung with soaked cotton inside was placed in the incubator where temperature was maintained at 37 °C.
Relative (RH) and absolute humidity and temperature of the circuit was measured electronically (Maphy+, S.K.I. Net, Inc.).
The results showed, firstly, RH went down below 90% when minute volume exceeded 12L/min. Secondary, air leak of 20% of the inspiration volume decreased RH below 90% when inspired minute volume exceeded 8L/min. Thirdly, addition of unheated cascade humidifier kept RH of the circuit at 100% in both of the above conditions throughout the minute volume of up to 20L/min by providing additional humidity of between 6 and 12 mg/L. We also reported additional effects of the atmospheric humidity as turbine ventilator inspired room air instead of dry gasses. Water content of HMEF increased approximately 8grams in seasons of high humidity whereas, that with dry gases was constantly 1.5±0.3grams(n=39). HMEF with water content of 8grams increased the inspiratory airway resistance by 33%.