pH monitoring is a test or study very widespread in gastroenterology and its main objective is to measure the levels of acidity in the oesophagus. The procedure usually takes a few minutes and is carried out by introducing a probe (equipped with acid-sensitive receptors) through the nose, slowly guiding it to the oesophagus. This probe contains an electronic device connected to a computer that measures and records the levels of acidity. This method is usually used mainly for patients suffering from gastroesophageal reflux or for those with arthritis and oesophageal pain. Normally, anaesthetics and sedatives cannot be used in this type of test.