Inspired air temperature with immersion heater humidifiers.

The temperature of aerosol mixture delivered from 2 types of immersion heater humidifiers was monitored at various sites along the delivery tube. As anticipated, the temperature of the humidified gas decreased as it moved distally from the aerosol generator to the T-adaptor in contact with patient's airway. The immersion heaters with fixed-temperature thermostatic control performed consistently, though most produced inhaled air temperatures higher than desired (greater than 37 degrees C). Immersion heaters with temperature reset features were in general unreliable and invariably gave higher inspired air temperatures with higher settings of the thermostat.