[Goals and methods of patient monitoring]

Monitoring during and after anaesthesia is aimed at recording changes in physiological functions including the patient's response to the anaesthetic and surgery, and identifying avoidable critical incidents caused by human error or equipment failure. Assessment and control of the depth of anaesthesia would be desirable but cannot yet be accomplished in clinical practice. For every anaesthetic, some degree of primary, basic or minimal monitoring is essential and is, in a number of countries, prescribed or recommended by regulations or guidelines. Besides an alert anaesthetist constantly observing the patient and monitoring the function of the anaesthesia machine, these minimal standards include an ECG, noninvasive blood pressure measurement, pulse oximetry, and end-tidal CO2 recording (capnography). ECG, blood pressure, and pulse oximetry also have to be employed during regional anaesthesia and in the post-anaesthesia care unit. The question as to whether further monitoring techniques need to be added (extended or secondary monitoring) will depend upon the medical problems of the individual patient and on the nature and duration of the surgical and anaesthetic procedures. For this purpose, invasive methods are preferentially used, in particular central venous and arterial pressure recording, and a pulmonary artery catheter for measuring pulmonary artery and pulmonary capillary wedge pressures and cardiac output, all in combination with blood gas analysis.