A randomized double-blind placebo-controlled trial to evaluate the value of a single bolus intravenous alfentanil in CT colonography

Background: Although CT colonography is a less invasive alternative for colonoscopy for the detection of colorectal polyps and cancer, procedural pain is common. In several studies, CT colonography pain and burden is higher than in colonoscopy. Apart from discomfort, anxiety and its related stress-induced peri-procedural side effects, this may influence the adherence for CT colonography as a possible screening tool for colorectal cancer. We hypothesize that a single bolus intravenous alfentanil will give a clinically relevant reduction in maximum pain defined as at least 1.3 point reduction on an 11-point numeric rating scale (NRS). Methods/Design: A randomized double-blind placebo-controlled trial in which patients scheduled for elective CT colonography in a single tertiary centre are eligible for inclusion. The first 90 consenting patient will be block-randomized to either the alfentanil group or the placebo group. Before bowel insufflation, the alfentanil group receives a single bolus intravenous alfentanil 7.5 mu g/kg dissolved in 0.9% NaCl, while the placebo group receives an intravenous bolus injection of pure 0.9% NaCl. For both groups an equal amount of fluid per kilogram (75 mu L/kg) is injected. The primary outcome is the difference in maximum pain on an 11-point NRS. Secondary outcomes include: pain and burden of different CT colonography aspects, side effects, procedural time and recovery time. For the primary outcome an independent samples t-test is performed and a P value < 0.05 is considered statistically significant. Discussion: This study will provide evidence whether a single bolus intravenous alfentanil gives a clinically relevant reduction in maximum pain during CT colonography.