American monitoring: standard and state of the art

Monitoring of the anesthetized patient, the anesthesia machine, and the patient-machine interface is an essential component of anesthetic practice in order to prevent anesthetic-related injuries resulting from equipment failure or human error. While the optimal monitor to detect anesthetic problems (hypoxia, esophageal intubation, hemodynamic compromise, for example) is unclear at present, American standards require continuous presence of qualified personnel who evaluate patient oxygenation, ventilation, circulation, and temperature. A common monitoring array includes electrocardiogram, autosphygmomanometer, pulse plethysmography/oximetry, stethoscope, anesthetic gas analyzer, thermistor, and nerve stimulator. The role of emerging technologies, including transesophageal echocardiography, automated electrocardiographic analysis of ST segments, transcranial Doppler, and transcranial near infrared spectroscopy are discussed.