[Patient monitoring during anesthesia]

Three functional levels are monitored during anaesthesia: vital functions such as cardiovascular and respiratory systems; metabolic functions; and organs such as brain and muscle. These three levels interact with each other and with the anaesthesia system. Basic monitoring systems include the ECG, noninvasive blood pressure measurement, inspired O2 concentration, tidal volume, airway pressure, and alarm systems for stenosis and disconnection. Other monitors are added to this list, including pulse oximetry, capnography, temperature, and neuromuscular transmission. The type of surgery and anaesthetic risk will determine the extent of the monitoring used during surgery. New and expensive noninvasive monitoring techniques such as transesophageal Doppler echocardiography and somatosensory evoked potentials will increasingly be added. The high costs and the rising number of monitoring systems necessitate a better definition of what is essential and what is optional for each individual case.