With approval from the ethics committee, we obtained written, informed consent from all the conservators of 20 patients who were ASA I, aged 1-96 months and scheduled to undergo elective surgical procedures. Moreover, we investigated the correlation between the effect of pediatric HME on CO 2 elimination and demographic variables. Therefore, in this study, we examined whether the PaCO 2 of healthy pediatric patients (1-96 months) was significantly influenced by the use of pediatric HME. However, when there was a big dead space ventilation, the EtCO 2 could not be representative of PaCO 2 and the ages of the study population were limited to under 2 years. However, that study examined how much more ventilation and breathing work were required to maintain the same end-tidal concentration of CO 2 (EtCO 2), but not the PaCO 2, in pediatric patients under 2 years old. One previous study was conducted to evaluate the effect of humidi-filters on dead space in pediatric patients.

Even when used in patients that are healthy without acute lung disease, smaller pediatric patients would be affected by the use of a pediatric HME.

The volume of a pediatric HME is generally 20-25 ml, which is about 1/10 of the tidal volume of a 20 kg patient or 1/5 for a 10 kg patient. However, with the exception of extremely small premature neonates, most pediatric patients undergoing general anesthesia are applied with only one size of pediatric HME between the tracheal adaptor and the Y piece. Therefore, most studies to evaluate the dead space effect of HME in adult patients have been conducted in ICU patients receiving lung protective ventilation with a lower tidal volume of 4-6 ml/kg. HME have a low resistance to airway flow and a relatively small volume (about 75 ml), which is not too large to impair ventilation of healthy adult patients ventilated with a tidal volume of 8-12 ml/kg. Heat-and-moisture exchangers (HME) are the most commonly used humidi-filters.

Dead space ventilation anesthesiology