What Is Monitored During Anesthesia, and Why
The four things your anesthesiologist is required to watch throughout your procedure, and the standard behind them.
American anesthesia practice is governed by a short, specific standard. The ASA's Standards for Basic Anesthetic Monitoring, first approved in 1986 and last amended in October 2025, apply to general anesthesia, regional anesthesia and monitored anesthesia care, and require that qualified anesthesia personnel be present in the room throughout those anesthetics, subject to the exceptions described in the document.1
The same standards require that oxygenation, ventilation, circulation and temperature be continually evaluated. The method used depends on the anesthetic: an oxygen analyzer is required for general anesthesia delivered through an anesthesia machine, oxygen saturation is measured by pulse oximetry for general anesthesia and deep sedation, exhaled carbon dioxide is assessed for general anesthesia and monitored for deeper sedation, an ECG is displayed continuously, blood pressure and heart rate are measured and recorded at least every five minutes, and temperature is monitored when a clinically significant change is intended, anticipated or suspected.1
What you can ask your anesthesiologist
Who will be with me throughout the procedure? What monitoring will be used? What will be done if my breathing needs support? The standards describe a minimum, not a ceiling: the ASA notes they may be exceeded at any time based on the judgment of the responsible anesthesiologist.1
Monitoring does not stop when the procedure ends
The same vigilance continues into recovery. The ASA's Standards for Postanesthesia Care require that patients be observed in a recovery area, with their condition documented, until they are stable, and that discharge is a physician responsibility.2 If you go home the same day, the monitors come off when the numbers — not the clock — say you are ready.
Sources
Dr. John Seitz, MD
Board-certified anesthesiologist
This article is for general educational purposes and is not a substitute for personalized medical advice. Always consult your physician for guidance specific to your health.