Loss of sensation with or without loss of consciousness. There are several ways of producing anesthesia, with the choice dependent on the type of surgery and the medical condition and preference of the patient. Each person responds differently to a given anesthetic, and anesthetic techniques and drugs often have marked effects on bodily functions, especially those of the cardiovascular and respiratory systems. Therefore, these systems are monitored closely during anesthetic administration, with measurements such as heart sounds, blood pressure, heart action (electrocardiogram), temperature, and oxygenation taken using a variety of sophisticated devices.