An endotracheal tube with an inflatable sealing cuff 20, the cuff having a patient end region 30 shaped so that inflates to contact and seal the wall of the trachea and a machine end region 31 arranged so it is inflated most of it is out of contact with the wall of the trachea. This enables gas permeating into the cuff at the patient end to permeate out of the cuff over the machine end region. The machine end region of the cuff may have an increased surface area compared to a cylindrical configuration and may comprise pleats. The machine end region may be more porous or thinner that the wall of the cuff in the patient end region. In another embodiment, the tracheal tube 1 has an inflatable cuff 20 with a patient end arranged to form a seal with the wall of the trachea, and anaesthetic gas in the trachea exposed to the cuff forwardly of the seal permeates through the cuff to a region rearwardly of the seal.
