Propofol vs Propofol + Benzo/Opiates in High Risk Group

The use of propofol (2,6-di-isopropofol) for sedation during endoscopic procedures has increased in recent years primarily because of its favorable pharmacokinetic profile compared with traditional endoscopic sedation with benzodiazepines and opioids. Propofol has a rapid onset of action (30-45 sec) and short duration of effect (4-8 min). There also are data to support the safe use of propofol for advanced endoscopic procedures such as endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic ultrasound (EUS).

There is limited information on the incidence of sedation related complications during advanced endoscopy. Prior studies were limited by controlled patient populations at low risk of developing sedation related cardiopulmonary complications. In a recent study, we defined the frequency of sedation related adverse events including the rate of airway modifications (AMs) with propofol use during advanced endoscopy. From a total of 799 patients, AMs were required in 14.4% of patients, hypoxemia in 12.8%, hypotension in 0.5% and premature termination in 0.6% of the patients. In addition, body mass index (BMI), male sex and American Society of Anesthesiologists (ASA) class of 3 or higher were independent predictors of AMs. Similarly, Wehrmann and Riphaus identified ASA class of 3 or higher, total propofol dose, history of alcohol use and having an emergency endoscopy as independent factors for sedation related complications in patients undergoing advanced procedures.

Given the alarming rates of obesity in the United States, it is believed that the prevalence of obstructive sleep apnea (OSA) may be 10% or higher and in obese adults these numbers could be as high as 25%. Using a previously validated screening tool for OSA [STOP-BANG (SB)], we reported a prevalence rate of patients at risk for OSA of 43.3% in patients undergoing advanced endoscopy procedures. Patients at risk for OSA with a positive SB score (score ≥ 3 of 8) had a higher rate of AMs (20% vs. 6.1%, adjusted relative risk 1.7) and frequency of hypoxemia (12% vs. 5.2%, adjusted relative risk 1.63) compared to those at low risk for OSA. Thus, based on the available data, it appears that ASA class 3 or higher, high BMI, and patients at risk for OSA are factors that place patients undergoing advanced endoscopy procedures at high risk for sedation related complications including airway modifications.

The optimal method for achieving deep sedation in this high risk group of patients is unclear. Propofol may accentuate airway collapse as patients become unresponsive to verbal stimulation (deep sedation). Recent studies suggest that propofol with midazolam and/or opioids may be synergistic in action and therefore the combined application of these drugs may permit smaller doses of each to be used and potentially lead to a reduction in risk of complications and in the dose of propofol needed while retaining the individual advantages of each compound. There is limited data evaluating the synergistic effect of propofol with midazolam and opioids in patients undergoing advanced endoscopy procedures. Ong and colleagues in a randomized controlled trial compared patient sedation and tolerance during ERCP using propofol alone or midazolam, ketamine and pentazocine (sedato-analgesic cocktail) for induction along with propofol for maintenance. Patient tolerance as assessed by visual analog scales by endoscopist and anesthetist were higher in the combination group. Paspatis et al reported higher dosage of intravenous propofol required in patients being sedated with propofol alone compared with that required in patients receiving oral dose of midazolam with propofol for ERCP procedures. In addition, the patients' anxiety levels before the procedure were lower in the combination group. The mean percentage decline in the oxygen saturation during the procedure was significantly greater in propofol alone group. However, these studies excluded patients deemed to be at a high risk for sedation related complications. Patients with ASA class 3 or higher were excluded, the mean BMI was less than 25, and included only patients at average risk for complications associated with sedation.

The significance of synergistic sedation in patients undergoing advanced endoscopy procedures in the high risk patients is unclear. The overall risk of sedation related complications is thought to be higher compared to standard endoscopy due to longer procedure times and the need for relatively deeper levels of sedation.