67 / 242
67
A MULTI-CENTRE RANDOMISED DOUBLE-BLIND PLACEBO-CONTROLLED TRIAL
6
BACKGROUND
Computed tomographic (CT) colonography is an accurate technique for the detection
of colorectal cancer and clinically relevant polyps and it is a less invasive alternative for
colonoscopy.
1-7
In clinical practice, CT colonography is widely used and it has been adopted
as colorectal cancer screening tool in the United States and is considered for screening in
other countries.
8,9
Sufficient colonic distension is mandatory for visualisation of the bowel wall,
10
but
insufflation causes the bowel to stretch and may result in painful colonic cramps.
11-16
Colonic insufflation is one of the most burdensome aspects of CT colonography.
13-15
In
several studies the pain and burden scores of CT colonography even compare adversely
with standard colonoscopy under moderate sedation,
11,12,15,16
although in other studies,
CT colonography is favoured over colonoscopy.
3,17
However, discomfort, pain, and anxiety
(including possible side effects of anxiety
18
) are detrimental for acceptance of the test, both
in clinical practice as in screening.
During conventional colonoscopy, administration of analgesics is regular practice. To the
best of our knowledge, no analgesics are administered during CT colonography and no
studies have evaluated this option. To induce sufficient analgesia for acute pain during CT
colonography, an opioid is most suitable because of the analgesic potency.
19-21
Hereby,
intravenous administration allows more precise timing of the peak effect compared with
oral administration.
In sigmoidoscopy, a fentanyl bolus has been proven to lower pain scores.
22
Because of the
CT colonography procedure time is approximately 20 minutes,
23
an opioid with a rapid
onset and short elimination time would be suitable and prevents long recovery times.
Alfentanil is such a short-acting opioid (maximumeffect within 1–2minutes and subsequent
distribution half-life values of 1 and 14 minutes).
24
The need for recovery facilities could have
negative consequences for its widespread clinical use for CT colonography and in particular
in screening.
25
Before considering the use of opioids during CT colonography, it is necessary
to demonstrate a clinically relevant pain reduction, beneficial effect on the burden, and
acceptance without detrimental effects on safety, procedure and recovery time.
We hypothesised that a single bolus intravenous alfentanil will give a clinically relevant
reduction in maximum pain score defined as at least 1.3-point reduction on an 11-point
numeric rating scale.
26-28