For measuring the epitympanic temperature we will use the Metraux Thermometer (Walpoth, Galdikas et al. 1994). The Metraux Thermometer is widely used in pre-hospital care in Norway and internationally. The ear-sensor will after induction of anaesthesia be inserted according to the manufacturers specifications in the auditory canal and activated. The sensor is two tiny and soft metal wires covered in a plastic wrapping integrated in a soft rubber earplug. The depth of the measuring point is pre-set from the manufacture to be approximately 10 mm from the tympanic membrane. The display will then show the epitympanic temperature in real-time.