Abstract: An apparatus for monitoring patient functions, particularly depth of anesthesia includes an oesophageal probe having a balloon located in the patient's oesophagus to provoke contractions thereof; a gas cylinder or pump for applying air or saline solution to the balloon and a sensor for detecting signals indicative of oesophageal contraction, from which signals the depth of anesthesia may be estimated.

Abstract: A method of monitoring the depth of anaesthesia of a patient, comprising stimulating contractions in the oesophagus of the patient, for example using an inflatable oesophageal balloon, obtaining signals indicative of the oesophageal contractions using a sensor, and deriving from the signals an output indicative of the rate of occurrence of signals having a magnitude greater than a preset threshold value, and apparatus for carrying out the method.An alternative aspect comprises assigning a score value to each of a plurality of different bodily functions of a patient, for example heart rate, blood pressure, degree of sweating, and formation of tears, the said score values being indicative of a depth of anaesthesia or sedation, summing the score values, and producing an output from the summed score values indicative of the amount of anaesthetic to be fed to the patient.