Providing adequate sedation and analgesia is an integral part of the practice of colonoscopy procedure.

There are various protocols and methods used to prevent discomfort and alleviate pain. Conscious sedation is one of the options recommended by the American Society for Gastrointestinal Endoscopy, although the choice of the exact protocol is left to the physician's discretion.

This study will attempt to recommend a preferred protocol based on a double blind randomized prospective method.

The efficacy of midazolam and ketamine will be compared to the efficacy of midazolam and fentanyl for sedation in ambulatory colonoscopies.

The results will be compiled from objective data and patient and physician interviews.

Inclusion Criteria:

• Candidates for elective colonoscopy at the Soroka Medical Center who have signed an informed consent.

Exclusion Criteria:

1. Hypersensitivity to benzodiazepines
2. Hypersensitivity to benzyl alcohol
3. Hypersensitivity to ketamine
4. Hypersensitivity to opiates
5. Pregnancy
6. Uncontrolled hypertension
7. Myocardial infarct in the last 6 months
8. CVA
9. Chronic pulmonary disease
10. Renal failure
11. Chronic liver disease (CHILD B or C)
12. Elevated ICP, cerebral hemorrhage or cranial SOL.
13. Hypovolemic shock
14. Glaucoma
15. Mental illness
16. Drug or alcohol addiction