Insertion of a temperature probe into the ProSeal® laryngeal mask airway drainage tube

Abstract

Background: Temperature monitoring is one of the minimum mandatory monitoring standards of anaesthesiology. Intraoperative hypothermia and hyperthermia can both be detrimental for patients. We introduced a temperature probe into a Proseal^® laryngeal mask airway (LMA) drainage tube, and measured patient temperatures and evaluated temperature dynamics. Methods: After obtaining informed consent, a thermistor probe (Datex S5^®) was inserted into the drainage tube of a Proseal^® LMA. This was done to monitor the intraoperative core body temperature in the distal one-third of the oesophagus, and was undertaken prospectively in 123 patients in whom the placement of an orogastric tube was not mandatory (e.g. orthopaedic, gynaecological and ophthalmic surgery). To confirm the position of the thermistor probe, a fibre-optic bronchoscope was inserted in the drainage tube immediately after removal of the temperature probe. Results: An increase in temperature, of 2°C ± 1.2°C, was observed from the midpoint to the tip of the drainage tube in more than 95% of cases. As the thermistor crossed the distal end of the drainage tube and entered the lower third of the oesophagus, there was a rapid increase in temperature. Conclusion: This is a useful method for monitoring core temperature in cases where a gastric tube is not required intraoperatively. This method can be used in all supraglottic devices that have a drainage tube, and is effective, cheap and reliable, with easy accessibility for accurate core temperature measurement.