Randomized Trial of Diphenhydramine Versus Continued Midazolam in "Difficult-to-sedate" Patients Undergoing Colonoscopy

• Proportion of patients who achieve adequate sedation to allow colonoscopy (defined as MOAA/S ≤3) [ Time Frame: Approximately 10 minutes or less ] [ Designated as safety issue: No ]
  

Patients who are undergoing colonoscopy and are not adequately sedated after initial standard sedation with midazolam 5 mg and fentanyl 100 mcg will be randomly assigned to receive diphenhydramine (up to 3 incremental doses of 25 mcg each) vs. continued midazolam (up to 3 incremental doses of 1.5 mg each). the level of sedation will be assessed using the MOAA/S scale 2-3 minutes after each administration to determine if they are sufficiently sedated to begin colonoscopy. The patient, the healthcare team involved in performing the endoscopy, and the investigator assessing sedation will be blinded to the therapy. Our hypothesis is that diphenhydramine will provide better sedation than continued administration of midazolam during colonoscopy in patients not achieving adequate sedation with standard doses of midazolam plus fentanyl.