Faced with growing demand for GI endoscopy procedures, declining reimbursements under Medicare's new ASC payment schedule and a shortage of anesthesia providers, GI facilities are looking for ways to maximize the benefits of propofol as a sedating agent (quicker induction and recovery times) while minimizing its biggest negative — the need for direct monitoring by someone trained in the administration of general anesthesia. Patient-controlled sedation with a cocktail of propofol and remifentanil appears to be a promising alternative to anesthesiologist-controlled propofol sedation and could introduce more flexibility to the anesthesia model for GI endoscopy.

The dilemma
More than 15 million colonoscopies are performed annually in the United States, and that number is growing as the population ages and awareness of the importance of colorectal cancer screening spreads. At the same time, the popularity of propofol as a sedating agent for this procedure is also growing because it's fast acting and reduces recovery times, letting GI facilities speed room turnovers and increase their caseloads. However, the FDA-approved label for propofol requires it to be administered by someone trained in the administration of general anesthesia, making the widespread use of this drug for the growing number of colonoscopy cases unfeasible from a manpower and financial standpoint.

Clinicians and manufacturers have come up with a number of potential solutions to this problem, including nurse-administered propofol, GI-directed propofol, patient-controlled sedation and computer-assisted personalized sedation. But in most of these cases, you have to limit the propofol dose to light sedation, producing results that aren't much different from fentanyl-midazolam. Recent work I've done with colleagues at the University of Pennsylvania shows that patient-controlled sedation with propofol and remifentanil during colonoscopy can both speed throughput and let anesthesia providers play "zone defense," attending to several patients at a time. The idea behind using propofol in conjunction with remifentanil is to give patients an added comfort level as opposed to just sedation, while delivering the same efficiency benefits of propofol, particularly the shorter emergence times.

How it works
A study my colleagues and I published in the journal Anesthesia & Analgesia about a year ago compared patient-controlled sedation with propofol/ remifentanil (PR) and with midazolam/fentanyl (MF). For the PR group, I used a 60cc syringe with propofol/remifentanil prepared by adding 1mg remifentanil to 100cc propofol (I've never needed more than 30cc for any patient). The loading dose is 3cc, and the bolus 0.3cc, with zero lockout. Patients are able to control their levels of sedation during the procedure by pushing the button on a PCA pump in response to painful stimuli.

Study patients who received a bolus of PR were sedated in about half the time as those in the MF group (3.4 minutes vs. 7.6 minutes). The average emergence time for patients in the PR group was about 5 minutes, and their recovery was significantly shorter than the procedure room time. The MF group had an average recovery time of 36.4 minutes.

One potential drawback of the propofol/-remifentanil cocktail is the risk of respiratory depression. In the initial study, 2 of the 25 patients in the PR group required anesthesia rescue. When that study was completed, we set out to do additional research comparing the rate of respiratory depression during anesthesiologist-controlled PR sedation and patient-controlled PR sedation. The results, which we reported at the American College of Gastroenterology's annual meeting in October 2008, suggest that the rate of respiratory depression under patient-controlled sedation is 1 ?5 that of anesthesiologist-administered sedation. Patients are able to maintain light sedation during non-stimulating portions of the procedure, quickly increase the depth of sedation during painful stimulus and return to light sedation. The full manuscript of the follow-up study is under review for publication.

The benefits
Patient-controlled sedation with PR has several potential time- and cost-saving benefits for GI facilities. By allowing faster induction, emergence and recovery times for colonoscopy cases, the technique could let you host more cases in a day while reducing your PACU and anesthesia personnel needs. Because the patients are only lightly sedated for most of the procedure, and periods of deep sedation can be anticipated from the demand sequence, anesthesiologists can multitask, supervising multiple contiguous locations instead of one at a time.

In addition to the time and cost savings, there's a public health benefit to finding safe, economical ways to administer sedation for GI endoscopy. By making this procedure more comfortable, convenient and affordable, more patients will opt for and have access to colorectal cancer screenings.