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Bispectral Index Monitoring During General Anesthesia

Policy Number: MP-262

Latest Review Date: September 2023

Category: Medical                                                                 


Bispectral index monitoring during general anesthesia to monitor the effects of anesthetics and sedatives on the brain is considered not medically necessary.


BIS monitors are non-invasive devices that reflect a signal-processed EEG.  They provide an index of the degree of sedation in patients receiving mechanical ventilation and sedative agents after surgery, trauma, or medical illness.

Sedation has historically been assessed indirectly, usually by using vital signs or subjective sedation scales.  However, due to limitations of these subjective assessment tools, over sedation and under sedation remain a major challenge. The bispectral index (BIS) is the hypnotic component of a continuous EEG parameter and ranges from an awake, no drug effect value of 95 to 100 to no detectable EEG activity with a value of zero.

The BIS monitor system consists of a sensor, a digital signal converter, and the monitor.  The sensor picks up the electrical signals from the cerebral cortex and passes them to the digital signal converter.  The digitized signals then travel to the device’s pre-processor, which filters out the stray high-frequency signals or “artifacts” resulting from patient movement or electrocautery equipment.  It then subjects the filtered EEG data to a sophisticated algorithm to determine the bispectral index, a numerical level between 0-100.  The BIS readings mean the following:  0 = no EEG activity; 40-60 = deep sedation; 70-80 = moderate sedation; 80-90 = light sedation; 100 = fully awake.

It has been proposed that the Bispectral Index (BIS) may be used to titrate volatile anesthetics more precisely to individual requirements.  This would avoid exposure to unnecessarily high concentrations of anesthetics while minimizing the likelihood of awareness during anesthesia.  These benefits may then correlate with faster emergence, shorter recovery times in the post-anesthesia care unit, and decreased adverse effects of anesthesia.


The most recent literature search was performed through September 14, 2023.

Summary of Evidence

The evidence for bispectral index monitoring during general anesthesia to monitor the effects of anesthetics and sedatives on the brain includes both randomized and nonrandomized clinical trials, as well as prospective follow-up studies. The relevant outcomes are change in disease status, treatment-related morbidity and mortality. There is a paucity of data in the controlled trials and a lack of standardized approach to bispectral index monitoring. The evidence is insufficient to determine the effects of the technology on health outcomes.

Practice Guidelines and Position Statements

Not applicable.

U.S. Preventive Services Task Force Recommendations

Not applicable.


Bispectral index (BIS) monitor, general anesthesia, BIS EEG VISTA MONITOR SYSTEM


Medtronic, Bispectral Index (BIS™) monitoring system



Coverage is subject to member’s specific benefits.  Group specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply

FEP: Special benefit consideration may apply.  Refer to member’s benefit plan.


CPT codes:               


Unlisted anesthesia procedure(s)


  1. Bigham C, Bigham S, Jones C. Does the bispectral index monitor have a role in intensive care? JICS 2012 Oct;13(4):314-319
  2. Bennett C, Voss LJ, Barnard JP, Sleigh JW. Practical use of the raw electroencephalogram waveform during general anesthesia: the art and science. Anesth Analg. 2009 Aug; 109(2):539-50.
  3. Bispectral index for improving anesthetic delivery and postoperative recovery (review) 2007.The Cochrane Collaboration
  4. Chollet-Xemard C, Combes X, et al.  Bispectral index monitoring is useless during cardiac arrest patients’ resuscitation.  Resuscitation 2009; 80(2): 213-216.
  5. DeDeyne, C.S. (2001) The acute care of traumatic brain injury. Current Opinion in Anaesthesiology 14(5) 475-481.
  6. Ekman A, et al.  Reduction in the incidence of awareness using BIS monitoring, Acta Anaesthesiology Scand, January 2004; 48(1): 20-26.
  7. Ely, EW, Truman, B., Shintani, A. Thomason, JWW, Wheeler, A.P., Gordon, S. et al (2003) Monitoring sedation status over time in ICU patients; the reliability and validity of the Richmond Agitation Sedation Scale (RASS) JAMA 289:2983-2991.
  8. IOM (Institute of Medicine). 2011. Clinical Practice Guidelines We Can Trust. Washington, DC: The National Academies Press.
  9. Johansen JW, et al.  Development and clinical application of electroencephalographic bispectrum monitoring, Anesthesiology, November 2000, Vol. 93, No. 5.
  10. Kreuer S, et al. (2005) Narcotrend or Bispectral Index Monitoring During Desflurane-Remifentanil Anesthesia: A Comparison with a Standard Practice Protocol. Anesthesia & Analgesia. Volume 101 - Issue 2 - p 427-434.
  11. Li XJ, Kang Y and Zhang C.  [A study of bispectral index monitoring in assessing the depth of sedation of patients under mechanical ventilation].  Zhongguo Wei Zhong Bing Ji Jiu Yi Xue 2009; 21(6): 361-363.
  12. Lindholm ML, Brudin L and Sandin RH.  Bispectral index monitoring:  Appreciated but does not affect drug dosing and hyp0notic levels.  Acta Anaesthesiol Scand 2008; 52(1): 88-94.
  13. Liu SS.  Effects of bispectral index monitoring on ambulatory anesthesia, Anesthesiology, August 2004, Vol. 101, No. 2.
  14. Miller:  Miller’s Anesthesia, 6th edition.  Bispectral Electroencephalographic Monitoring.
  15. Myles PS, et al.  Bispectral index monitoring to prevent awareness during anesthesia:  The B-aware randomised controlled trial, Lancet, May 2004; 363(9423): 1757-1763.
  16. O’Connor MF, et al.  BIS monitoring to prevent awareness during general anesthesia, Anesthesiology, March 2001; 94(3): 520-522.
  17. Pavlin JD, et al.  Effects of bispectral index monitoring on recovery from surgical anesthesia in 1580 inpatients from an academic medical center, Anesthesiology, March 2005, Vol. 102, No. 3.
  18. Practice parameters:  Practice advisory for intraoperative awareness and brain function monitoring,
  19. Sebel, P.S., Lang, E., Rampil, I.J., et al (1997) A Multicenter study of bispectral electroencephalogram analysis for monitoring anesthetic effect. Anesthesia and Analgesia, 84: 891-899.
  20. Sebel PS, et al.  The incidence of awareness during anesthesia:  A multicenter United States study, Anesthesia Analg 2004; Vol., 99, p. 833-839.
  21. Weaver CS, Hauter WH, et al.  An assessment of the association of bispectral index with 2 clinical sedation scales for monitoring depth of procedural sedation.  American Journal of Emergency Medicine 2007; 25: 918-924.


Medical Policy Group, January 2006 (2)

Medical Policy Administration Committee, February 2006

Available for comment February 16-April 3, 2006

Medical Policy Group, January 2008 (1)

Medical Policy Group, January 2010 (1)

Medical Policy Group, September 2012 (3): Effective September 14, 2012 this policy is no longer scheduled for regular literature reviews and updates.

Medical Policy Group, October 2019 (3): 2019 Updates to Key Points. A peer review literature analysis was completed and no new information was identified that would alter the coverage statement of this policy. This policy will remain on biannual reviews.

Medical Policy Group, August 2021 (6): Updates to Description, Key Points, Practice Guidelines, Key Words, USPTF, Governing Bodies and References.

Medical Policy Group, October 2022 (3): 2022 Updates to Key Points. Reviewed by consensus. No new published peer-reviewed literature available that would alter the coverage statement in this policy.

Medical Policy Group, September 2023 (3): 2023 Updates to Key Points and Benefit Applications. Category changed from Other to Medical. Reviewed by consensus. No new published peer-reviewed literature available that would alter the coverage statement in this policy.

This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.