Best Evidence Topics
  • Send this BET as an Email
  • Make a Comment on this BET

The use of bispectral index monitoring (BIS) in conscious sedation

Three Part Question

In [adult patients requiring conscious sedation in the Emergency Department] does the use of [bispectral index monitoring] improve [safety]?

Clinical Scenario

A 25-year-old man presents to the emergency department (ED) with a fracture dislocation of his ankle. His ankle needs reducing, and you intend to use conscious sedation to facilitate this. You wonder whether bispectral index monitoring (BIS) would help achieve an appropriate level of sedation, thereby reducing the risk of respiratory depression while maintaining comfort. .

Search Strategy

A literature search of EMBASE (1980—week 2 February 2015), MEDLINE (1950—week 2 February 2015) and CINAHL (1981—week 2 February 2015) was conducted via NHS Evidence. The Cochrane database and Google Scholar were also searched.
Medline and CINAHL

[“bispectral index.”ti.ab OR BIS.ti.ab OR exp CONSCIOUSNESS MONITORS] AND [“conscious sedation.”ti.ab OR “propofol sedation.”ti.ab OR “procedural sedation.”ti.ab OR exp CONSCIOUS SEDATION] AND [emergenc*.ti.ab OR exp EMERGENCY MEDICINE]


[“bispectral index.”ti.ab OR BIS.ti.ab OR exp BISPECTRAL INDEX] AND [“conscious sedation.”ti.ab OR “propofol sedation.”ti.ab OR “procedural sedation.”ti.ab OR exp CONSCIOUS SEDATION] AND [emergenc*.ti.ab OR exp EMERGENCY MEDICINE]

Both searches were limited to English language and adults.

Search Outcome

MEDLINE; 10 papers, EMBASE; 11 papers, CINAHL; 5 papers, Cochrane database; 4 papers, Google Scholar; 51 papers.

Thirteen unique studies were identified after removal of duplicates. Six were discarded as not relevant after review of abstract.

Seven full articles were reviewed, two of which were not relevant and two were not based in the emergency department.

Three articles were therefore reviewed for this BET.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Miner et al
108 adult patients monitored with BIS during procedural sedation in the EDProspective observational study Respiratory depression rate20.8% if lowest BIS score > 70 compared to 56.7% if lowest BIS score < 70Observational study Small sample size Convenience sample Unclear who reported the complications (reporting bias) Patient baseline characteristics not assessed
Rate of recallSignificantly higher if lowest BIS score > 85 compared to < 85 (p = 0.001)
Perceived pain, as measured using a visual analogue scaleSignificantly higher if lowest BIS score > 85 compared to < 85 (p = 0.003)
Miner et al
105 adult patients radomised into two groups Excluded: alcohol intoxication, pregnancy, hypersensitivity to propofol Physicians performing sedation were either blinded or unblinded to the BIS score Prospective randomised controlled trial Difference in rate of respiratory depressionNo significant difference between groups when a single bolus of propofol was used, but overall lower rate of respiratory depression in unblinded group (p = 0.06)Arbitrarily powered to detect a 20% difference in rate of respiratory depression Complications recorded by performing physician Method of randomisation unclear Propofol doses not standardised Comorbidities and airway assessment were not considered
Perceived pain, as measured using a visual analogue scaleLower in unblinded group
Rate of perceived recallNo difference between groups
Miner et al
77 adult patients requiring procedural sedation with propofol for reduction of fracture or dislocation Excluded: patients with propofol hypersensitivity, alcohol intoxication, pregnancy Patients randomised to a predefined target sedation level of moderate or deep Prospective randomised clinical trialRate of respiratory depressionNo difference between groups (p = 0.92)Powered to detect effect size of 0.44 with resulting possibility of type 2 error Groups were analysed according to the preassigned sedation level, though in many cases, this sedation level was not achieved Depth of sedation was recorded postprocedure by the sedating physician Despite predefined definitions, it is likely there would be some inter-rater variability Propofol doses not standardised
Ease of procedureNo difference between groups (p = 0.72)
Perceived pain or recall of procedureStatistically significant difference between moderate and deep sedation (p = 0.04)


No single randomised controlled trial (RCT) has been conducted to directly address the proposed three-part question, which was focused on patient safety. Both the 2003 and 2005 studies found a statistically significant difference in the rate of respiratory depression occurring between groups and support the use of BIS monitoring to reduce the risk of respiratory depression. In contrast, the 2007 study found no difference in the incidence of respiratory depression between moderate and deep sedation groups, although this study was powered to detect a larger difference than the other two studies. It is possible that BIS monitoring might have an important role in improving the safety of conscious sedation when used in conjunction with other recommended monitoring. Further work is therefore indicated, ideally in the form of an RCT, to investigate the benefits of bispectral index monitoring both in terms of improved patient safety and patient experience.

Clinical Bottom Line

At present, there is insufficient evidence to support the routine use of bispectral index monitoring during conscious sedation.


  1. Miner JR, Biros MH, Heegaard W, et al. Bispectral electroencephalographic analysis of patients undergoing procedural sedation in the Emergency Department. Acad Emerg Med 2003;10:638–43.
  2. Miner JR, Biros MH, Seigel T, et al. The utility of the bispectral index in procedural sedation with propofol in the Emergency Department Acad Emerg Med 2005;12:190–6.
  3. Miner JR, Huber D, Nichols S, et al. The effect of the assignment of a pre-sedation target level on procedural sedation using propofol. J Emerg Med 2007;32:249–55.