Colonoscopy and sedation are frequently accompanied by hypotension, which reduces the amount of sedation able to be employed. Blood pressure is restored by the infusion of intravenous normal saline. Prophylactic infusion of normal saline may enhance the colonoscopy completion rate, and patient comfort during colonoscopy and during the recovery from colonoscopy.

The investigators propose randomising consenting adult patients attending outpatient colonoscopy to one of two treatment arms:

(i) A control arm

(ii) A treatment arm, with pre-hydration with an infusion of 1.0 litre of normal saline immediately prior to colonoscopy.

Outcome measures include colonoscopy completion rates, hypotension during or after colonoscopy, and patient ratings of comfort and satisfaction.

Outpatient colonoscopy is a generally well-tolerated elective procedure. Colonoscopy completion rate is governed in part by patient comfort, which is enhanced by adequate sedation. In addition, comfort following colonoscopy determines timely recovery from the procedure and return to usual activities.

Colonoscopy and sedation are frequently accompanied by hypotension (systolic blood pressure less than 100 mm Hg), which reduces the amount of sedation able to be employed. Where apparent, blood pressure is restored by infusion of intravenous normal saline. We have observed that hypotension is relatively common and may be present at or shortly after the commencement of the procedure, suggesting that many patients undergoing colonoscopy have reduced blood volume. Therefore, prophylactic infusion of normal saline may enhance colonoscopy completion rate, and patient comfort during colonoscopy and during recovery from colonoscopy.

We propose randomising consenting adult patients attending outpatient colonoscopy to one of two treatment arms:

(i) A control arm, with standard sedation and monitoring during colonoscopy, and infusion of normal saline if systolic BP ≤ 95 mmHg for more than 3 minutes (two observation periods) until completion of the procedure;

(ii) A treatment arm, with pre-hydration with an infusion of 1.0 litre of normal saline immediately prior to colonoscopy.

Outcome measures include colonoscopy completion rates, hypotension during or after colonoscopy, and patient ratings of comfort and satisfaction.

Inclusion Criteria:

• Aged 18 or older
• Able to provide informed consent
• Booked for outpatient colonoscopy, where appointment has been generated by Gastroenterology Unit bookings staff.

Exclusion Criteria:

• Booked for anaesthetist-supervised colonoscopy because of previous sedation difficulties or significant co-morbidity (American Society of Anesthesiology Class III or IV)
• Subjects requiring dialysis
• Subjects receiving parenteral nutrition
• Subjects with current congestive cardiac failure
• Subjects with conditions preventing placement and accurate use of the automatic blood pressure cuff on the left arm, such as morbid obesity or lymphoedema