Our hypothesis is that adding midazolam and/or fentanyl to propofol sedation for elective outpatient colonoscopy increases cognitive impairment at hospital discharge without improving intraoperative conditions or reducing intraoperative side-effects.

200 healthy patients aged 18 years or older will be randomised to receive propofol or propofol plus midazolam and/or fentanyl. Cognitive impairment will be tested at hospital discharge using Cogstate computerised testing software.

A great variety of drug combinations are administered to patients having elective outpatient colonoscopy. In addition, as patients are going home, some may have residual cognitive deficits that making leaving the hospital unsafe. This study aims to find drugs combinations that are associated with the least cognitive impairment.

Inclusion Criteria:

• Aged 18 years or older presenting for elective outpatient colonoscopy following full bowel preparation

Exclusion Criteria:

• No cognitive impairment
• Adequate English language comprehension
• Not combined with other procedures