Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy of Propofol or Midazolam Versus Placebo for Preoperative Medication in Patients Undergoing Elective Orthopedic Surgery

The role of anxiolytic premedication in the ambulatory surgical population is frequently debated. Anesthesiologists may consider the administration of anxiety-reducing drugs unnecessary when anxiety levels are low in outpatients presenting for minor surgery. However, the previous study reports that up to 80% of outpatients expressed a preference for a combination of anxiety-reducing and hypnotic premedication before surgery (1-4). In addition to anxiolysis, goals of anxiolytic premedication include sedation, amnesia, improved patient cooperation, and/or improved patient satisfaction. Intravenous (IV) midazolam is the most commonly used premedicant in the ambulatory setting due to its rapid onset, and short half-life (2,3,5), but its residual effects in the immediate postoperative period may contribute to postoperative sedation, as well as to delayed recovery and discharge-readiness after brief outpatient surgery. Furthermore, White et al. (6) noted that the slope of the dose-response curve for sedation was much steeper with midazolam compared with diazepam, which suggests that midazolam may possess a smaller margin of safety and greater need for careful titration to achieve the desired clinical end-point without untoward side effects.

Propofol has become the IV (intravenous) anesthetic of choice for ambulatory anesthesia because of its excellent recovery profile (7). Clinical experience with propofol in the ambulatory setting suggests that its use is associated with less residual sedation and lower incidence of postoperative nausea and vomiting (PONV) (8). However, there are some undesirable side effects associated with propofol including pain on injection, cardiovascular and respiratory depression, and occasional excitement on emergence from anesthesia (9). Practically, small doses of propofol (10-20 mg IV) have been used as an anxiolytic/sedative medication.

To date, there is only one study that has evaluated propofol versus midazolam versus placebo as premedication (10). In this study, the authors stated that propofol (0.4 mg/kg IV) had anxiolytic effects comparable in magnitude and duration to midazolam (0.04 mg/kg IV) with less memory impairment, respiratory depression and dizziness. However, they did not assess the efficacy of propofol and midazolam as a premedication on the recovery profiles and patient's satisfaction in their study. Compared to placebo and propofol, midazolam was associated with more frequent respiratory depression and significant impairment of anterograde explicit memory. Both propofol and midazolam helped relieve anxiety and lowered blood pressure (compared to baseline) but both were associated with greater dizziness scores (P<0.001, compared to placebo).

They concluded that Propofol had an anxiolytic effect comparable in magnitude and duration to that of midazolam with less memory impairment, respiratory depression and dizziness.

Propofol appears to be an economical, effective and safe alternative to midazolam for treating pre-anesthesia anxiety, and especially to be used for induction of anesthesia (10). (This sentence is not clear).