An expiratory limb is provided that is configured to remove humidified gases from a patient and configured to provide improved drying performance by providing a tailored temperature profile along the limb. Limbs for providing humidified gases to and/or removing humidified gases from a patient are also provided, the limbs having improved gas residence time at constant volumetric flow rate. The improved residence time can be achieved by providing a limb comprising multiple lumens.
