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Bhavani Shankar Kodali MD

Updated September 2022

ASA Standards of monitoring during anesthesia


ASA Standards of monitoring during anesthesia

Bhavani Shankar Kodali MD




ASA standards of monitoring







ASA Standards of Care - Capnography in 1990s. Pulse oximetry in 1989 followed by capnography.

1999 - Included capnography for mask anesthesia 

Standard for "every patient receiving general anesthesia

Continual monitoring for the presence of expired carbon dioxide

Identification of expired CO2 to verify correct positioning of an endotracheal tube or laryngeal mask

Capnography for monitoring ventilation - 2011



Updated October 1st, 2020

The readers are encouraged to read APSF Newsletter 2020;3:69-108. This will be on website as pdf format at

Dr John Eichhorn traces back the history of ASA standards of monitoring from Harvard to ASA. The following are some notable events from this review.

Starting in the mid 1970s, there was a critical explosion of medical malpractice lawsuits in the United States culminating in expensive settlements and jury awards for anesthesia accidents.  This received widespread publicity in Television and other media. A 1982 ABC special described anesthesia catastrophes: The Deep Sleep: 6000 will Die or Suffer Brian Damage. Then ASA President, Late DRr Ellison Pierce, Jr, MD, was deeply concerned about this problem, particularly anesthesia fatalities caused by very late recognition of accidental incorrect placement of endotracheal tubes into the esophagus.  He initiated the creation of the ASA Standards Committee to address preventable issues. He asked the Committee to base their approach of Harvard Anesthesiologists unpublished recommendations. In the early 1980s at Harvard's 9 teaching hospitals, anesthesiologists constituted 3% of faculty, but accounted for 12% of the malpractice insurance pay-outs, which approximated the national statistics. This perceived excessive danger led a 'Harvard risk management committee' chaired Dr John Echhorn to create a 1985 set of anesthesia standards as a response, and these Harvard standards became a template for the ASA subsequent efforts. Both committees stressed a need to change the behavior of anesthesiologists to prevent mishaps during anesthesia. Accordingly, the first set of recommendations came as not labelled as 'Guidelines', but as 'Standards'. This fact had enormous medical-legal implications and was unprecedented in American health care. An accident causing patient injury during willful deviation from these standards would be a guaranteed automatic loser in a malpractice lawsuit.  This was an obvious incentive for all practitioners to follow to implement the monitoring prescribed by the standards. Monitoring standards were introduced with no randomized studies. It would be unethical to perform anesthesia without monitoring. However, a 1989 detailed retrospective analysis of the catastrophic anesthesia accidents among 1,001,000 ASA Class I and II patients at the Harvard hospitals that prompted original concerns  there suggested that the large majority of accidents, prior to the introduction of standards, (88% of malpractice insurance pay-outs) would have been prevented by the strategies listed in the Standards. Implementation of Standard of monitoring resulted in a 66% reduction in malpractice insurance premiums over the period from 1986 to 1991. In one year, 1989, malpractice premium was cut by 33%. This was the direct proof of success of implementation of monitoring standards. This trend was not limited to Harvard anesthesiologists but through out the country. In 1990, the ASA leadership suggested: 'Abiding by the ASA Standards of Basic Intra-Operative Monitoring and using pulse oximetry and capnography may result in siginificant savings for anesthesiologists now negotiating new policies."



In 1998, the ASA (American Society of Anesthesiologists) Committee on Standards of Care continued its ongoing efforts to refine and update the ASA "Standards for Basic Anesthetic Monitoring," which were first adopted in their original form in 1986 and have been modified several times since. Two substantive amendments that were somewhat different from the Committee's proposals were adopted by the ASA House of Delegates in October 1998 and become effective July 1, 1999. Members and other interested parties will find the full text of all the monitoring standards on pages 462-463 of the 1999 ASA Directory of Members.


Mandatory Monitoring of Expired CO2


The first and most general point in the "methods" section of the ventilation monitoring standard was modified in such a way as to include capnography as a standard for "every patient receiving general anesthesia." This includes inhalation anesthesia via face mask: "Continual monitoring for the presence of expired carbon dioxide shall be performed unless invalidated by the nature of the patient, procedure, or equipment. Quantitative monitoring of the volume of expired gas is strongly encouraged.*" (As usual, this standard has the asterisk referring to the ability of the responsible anesthesiologist to waive the requirements under extenuating circumstances.) 


This strengthening of ventilation monitoring was intended by the committee as both recognition of the extremely valuable role of capnography and as a logical lead-in to the following standard previously modified to require identification of expired CO2 to verify correct positioning of an endotracheal tube or laryngeal mask. Testimony during the proposal and evaluation process raised two main issues. With the recent potential blurring of the distinction between intravenous sedation and general anesthesia, it was recommended that a clear definition of general anesthesia be developed. Also, concern was expressed about whether capnography will be required in brief, entirely noninvasive procedures such as cardioversion or electroconvulsive therapy during which an anesthesia machine may not even be used. The committee notes that the caveat about the nature of the procedure and the equipment likely will allow the responsible anesthesiologist to use his/her own judgment as to the validity of capnography for those procedures.


Further, the committee acknowledged the fact that the "end-tidal CO2" numerical value displayed on a monitor during mask anesthesia often may be influenced by gas mixing in the patient's airway and in the mask. However, the patient-safety orientation, particularly the detection of the failure of ventilation, was seen as key, with the integral role of capnography relating to the basic questions: "Is there expired CO2? Is it clearly too high or too low?" and "Is there any trend?"


John H. Eichhorn, M.D., was the founding editor and publisher of the APSF Newsletter. He lives in San Jose, CA as retired Professor of Anesthesiology, and continues to serve on the editorial board of APSF.


Eichhorn JH. ASA adopts basic monitoring  standards. APSF Newsletter 1987;2:1

Eichhorn JH et al. Standards for patient monitoring during anesthesia at Harvard Medical School. JAMA 198 6;256:1017-20.

Pierce EC. Anesthesiologists' malpractice premiums declining. APSF Newsletter 1989;4:1

Echhorn JH. Prevention of intra operative anesthesia accidents and related severe injury through safety monitoring. Anesthesiology 1989;70:572-577.

Eichhorn JH. Monitoring standards: role of monitoring in reducing risk of anesthesia. Problems in Anesthesia 2001;13:430-443.

Turpin SD. Anesthesiologist's claims, insurance premiums reduced: improved safety cited. APSF Newsletter 1990;5:1

American Society of Anesthesiologists, Standards of Basic Anesthetic Monitoring, Last Amended: October 28, 2015