View from a Gastroenterologist

Anesthesiologist-directed sedation for ambulatory endoscopic procedures has enjoyed an unparalleled and unbridle growth in recent years. Between 2003 and 2009, payments for anesthesiologist-directed sedation tripled from just under $400 million to 1.3 billion. This dramatic upsurge was driven not by increased cost but by increased utilization, which occurred almost exclusively in the commercial payor sector. Liu and colleagues estimated that of the $1.3 billion being paid for anesthesiologist-directed sedation, only $200 million was earmarked for high-risk patients.1 As gastroenterologists evolve from fee-for-service to value-based care, and eventually to a more risk-based landscape, we must ask ourselves, what are the prospects for anesthesiologist-directed sedation for low-risk ambulatory endoscopic procedures such as colonoscopy in healthy patients? Please keep in mind that colonoscopy relative value units continue to erode and the work associated with delivering procedural sedation has been pared from the procedural codes. When we critically dissect the value proposition for anesthesiologist-directed sedation in this scenario, what do we find? The results may surprise and scare you.

Does anesthesiologist-directed sedation lead to improvements in the outcomes of ambulatory endoscopic procedures? Dominitz et al. utilized a sample of Medicare administrative claims submitted for 328,177 adults undergoing outpatient colonoscopy.2 The authors found no difference in the polyp diagnosis rates between anesthesiologist-directed sedation and endoscopist-directed sedation (OR 1.04; 95 percent CI: 0.99,1.09).2 Recent studies have shed a sobering light on the notion that anesthesiologist-directed sedation is a safer avenue for ambulatory endoscopic sedation. Please keep in mind that the use of targeted moderate sedation allows feedback from our patients. A signal of discomfort from a patient during colonoscopic insertion should trigger not only a reassement of the current depth of sedation, but also whether the technique of the endoscopist should be altered due to instrument looping or over insufflation.

At this juncture, let’s remind ourselves that propofol has no analgesic properties. Hence, anesthesiologist-directed sedation blows past the moderate sedation mile marker and into deep sedation or general anesthesia to make up for this shortfall: There is no patient feedback to noxious stimuli.

Korman et al. utilized a colonoscopy force-monitor system to access the physics of colonoscopic insertion/withdrawal in a case-control study pitting monitored anesthesia care against moderate sedation with an opioid and benzodiazepine.3 The authors found that the maximum torque, push and pull force were significantly higher in the monitored anesthesia care (MAC) group. Although the authors did not find an association between higher force application and adverse events, they pointed out that the forces generated in some of the MAC group cases exceeded the thresholds needed to generate perforations and tears in cadaveric and surgical specimens.4 The authors also found that MAC significantly decreased the overall examination time. Is the augmented force application an appropriate price to pay for reducing the procedure time by a couple of minutes?

Wernli et al. conducted a prospective cohort study of 3,168,228 colonoscopy procedures from an administrative claims database to determine the 30-day complication profile.5

After adjusting the multivariate logistic regression model for age, gender, Charlson comorbidity index, geographic region and polypectomy status, the authors found that anesthesiologist directed sedation (ADS) was associated with a 13 percent higher risk of any complication studied within the 30-day window (95 percent CI:1.12,1.14). This included perforation, bleeding, abdominal pain, complications secondary to anesthesia, stroke and other central nervous system events. In fact, there was no complication subcategory that was reduced in association to ADS. In the previously mentioned study by Dominitz et al., there was no difference in the rates of bleeding, perforation, emergent hospitalization or emergency room visit within 30 days. In a retrospective cohort study of 1.38 million upper endoscopy and colonoscopy procedures in the Clinical Outcomes Research Initiative National Endoscopic Database, a composite of serious adverse events was compared between ADS and endoscopist-directed sedation utilizing a propensity analysis.6 For colonoscopy, when compared to endoscopist-directed sedation, there was no safety benefit for anesthesiologist-directed sedation (OR 0.93, 95 percent CI: 0.82,1.06). For upper endoscopy however, the propensity adjusted risk for serious adverse events was higher for anesthesiologist-directed sedation (OR 1.33; 95 percent CI: 1.18, 1.50). The increased risk was present for patients who were classified as either ASA I/II or III.

One of the purported benefits of ADS is theorized to be improved patient satisfaction, which will, in turn, lead to greater acceptance of procedures such as a screening colonoscopy. Since there are no randomized controlled trials comparing ADS to GI-administered sedation, we will need to extrapolate somewhat. In the meta-analysis of McQuaid and Laine, patient satisfaction for propofol versus and benzodiazepine and opioid did find an advantage for the former (RR 0.90; 95 percent CI:0.83, 0.97), but it is important to point out that the propofol in these studies was administered under the direction of the endoscopist.7

And so, we are left in a quandary. We have no direct comparative data between anesthesiologist- and gastroenterologist-directed sedation. Unfortunately, we may never see that study completed. However, a surging tide of evidence shows that there is at best no safety benefit with ADS and no improvement in polyp detection. Additionally, if we are to believe that gastroenterologist-directed propofol sedation carries with it the same outcomes as anesthesiologist-directed sedation, the improvement in patient satisfaction is modest at best. We are then left with sedation practice that probably improves throughput but has a huge cost from payor perspective: a cost that is in the regulatory crosshairs and is ripe for reduction and curtailment.

Dr. Vargo has no conflicts to disclose.


1. Liu H, Waxman DA, Main R, Mattke S. Utilization of anesthesia services during outpatient endoscopies and colonoscopies and associated spending in 2003–2009. JAMA 2012;307:1178-1184.

2. Dominitz JA, Baldwin LM, Green P, et al. Regional variation in anesthesia assistance during outpatient colonoscopy is not associated with differences in polyp detection or complication rates. Gastroenterology 2013;144:298-306.

3. Korman LY, Haddad NG, Metz DC, et al. Effect of propofol anesthesia on force application during colonoscopy. Gastrointest Endosc 2014;79:657-662.

4. Wu TK. Occult injuries during colonoscopy. Measurement of forces required to injure the colon and report of cases. Gastrointest Endosc 1978;24:236-238.

5. Wernli KJ, Brenner AT, Rutter CM, Inadomi JM. Risks associated with anesthesia during colonoscopy. Gastroenterology 2016;150:888-94.

6. Vargo JJ, Niklewski PJ, Willams JL, et al. Patient safety during sedation by anesthesia professionals during routine upper endoscopy and colonoscopy of 1.38 million procedures. Gastrointest Endosc 2016; epub.

7. McQuaid KR, Laine L. A systematic review and meta-analysis of randomized control trials of moderate sedation for routine endoscopic procedures. Gastrointest Endosc 2008;67:910-923.

One comment

  • Dr. Vargo is correct that in 2014 we published a study demonstrating that certain forces were greater with propofol than moderate sedation. We stated that because this was an observational study, a randomized trial would be necessary to validate these findings.
    We presented data at DDW 2015 and 2016 studies using our force monitoring technology that led us to the conclusion that the critical factor in force application is the endoscopist and not the form of anesthesia. In addition, we performed a study suggesting that the use of larger diameter instruments was associated with more force application. In a randomized study of over 70 patients performed by 7 endoscopists and randomized to moderate vs propofol anesthesia we did not show any differences in force application. The major determinant of force was the endoscopist. This paper is now in preparation.
    We concluded that it was not the method of anesthesia but the endoscopist technique that was critical to the amount of force used.

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