The depth of sedation provided by propofol during colonoscopy may be greater than necessary, according to researchers who objectively monitored it in their patients.
The study was prompted by a recent population-based analysis (JAMA Intern Med2013;173:551-556) suggesting that complications—especially aspiration pneumonia—are increased during cases with anesthesia assistance.
“No studies have measured the depth of sedation in patients receiving propofol for colonoscopy,” said Basavana Goudra, MD, of the University of Pennsylvania, in Philadelphia.
Dr. Goudra and his colleagues compared the depth of sedation between propofol and non–propofol-based sedation during colonoscopy, as measured by an electroencephalogram-based monitor, SEDline (Masimo), which displays the patient state index (PSI). Dose and timing of administered sedatives were independent of PSI values.
Of the 87 patients studied, 44 received endoscopist-guided sedation without propofol (midazolam/fentanyl with or without diphenhydramine) and the remaining patients received propofol administered by a nurse anesthetist. Demographic variables, including mean age, sex and weight, were comparable in both groups. The gastroenterologist and nurse anesthetist were blinded to PSI values.
A dedicated research assistant watched the SEDline monitor and noted the PSI scores at baseline, at the time of unresponsiveness (coinciding with insertion of the colonoscope), on removal of the scope and when the patient was appropriately responsive. The researchers also determined the time spent in the various levels, or spectra, of sedation. These spectra—PSI scores of 0 to 25, 25 to 50, 50 to 75 and 75 to 100—indicate deep general anesthesia; general anesthesia/deep sedation; and mild to moderate sedation, respectively.
“While awake, the typical patient has a PSI of 90 to 100, which drops into the 80s, 70s and so forth with titration,” said Augustus Carlin, a medical student at Drexel University, in Philadelphia, who presented the findings at the 2014 annual meeting of the American Society of Anesthesiologists (abstract 1230). “In colonoscopy, we are aiming for mild to moderate sedation.”
Sedation Much Deeper With Propofol
“We found that patients who received propofol were much more deeply sedated,” Mr. Carlin said. Although this is no surprise, he said it is important to objectively quantify the effect.
Dosing of sedatives in all patients was guided by clinical responsiveness and aimed at achieving minimum patient movement. SEDline scores at scope insertion were significantly lower in the patients who received propofol: 52 versus 73 for those given midazolam/fentanyl (P=0.004). SEDline scores when patients became responsive to verbal commands were also significantly lower with propofol sedation: 62 versus 79 (P<0.001), the researchers reported. Patients receiving propofol spent a much greater percentage of time in the deepest phases of sedation.
“Patients receiving propofol were much more deeply sedated, and most patients were in the range of general anesthesia [PSI, 25-50], whereas those with IV conscious sedation were mostly in the moderately sedated range [PSI, 50-75],” Mr. Carlin said.
The mean total duration of sedation was significantly longer in the propofol group, 34 versus 24 minutes (P=0.003), as was the time interval from insertion to removal of the colonoscope: 24 versus 17 minutes (P=0.007).
Dr. Goudra added that no aspirations occurred in these patients, for whom the risk is low: approximately one patient per 2,000 to 3,000 receiving propofol. Nevertheless, he added, “We know that patients receiving propofol are much more deeply sedated, which means a higher aspiration risk. We believe that, with appropriate titration, all the benefits of propofol sedation can be realized, with a possible reduction in risk.”
Use of a monitor such as the SEDline could optimize the titration of propofol, but whether it is cost-effective in practice is another issue, Dr. Goudra acknowledged. Anesthesiologists should understand more about depth of sedation, he said, and monitors such as SEDline would help them be more accurate.
Safe in Anesthesiologists’ Hands
Jeffrey Jacobs, MD, president of the Florida Society of Anesthesiologists, said the risks associated with propofol have been “exaggerated,” and the drug has “a long track record of safety when administered by an anesthesia professional.”
The Centers for Medicare & Medicaid Services recently indicated that because cost should not be a barrier to screening colonoscopy, it will reimburse for anesthesiologist-led sedation, Dr. Jacobs added.
“Everything carries a risk, but we attempt to identify patients who are most likely to aspirate, such as those with diabetes-related gastroparesis,” Dr. Jacobs said. “Maybe there are subsets of patients, like them, who could benefit from depth-of-sedation monitoring, as was done in this study. Of course, if there’s an opportunity to use less propofol, that’s always great; but in our experience, gastroenterologists and patients prefer the deeper sedation.”