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

Pain is common during colonic insufflation required for CT colonography. We therefore evaluate whether a single intravenous alfentanil bolus has a clinically relevant analgesic effect compared with placebo in patients undergoing CT colonography. A prospective multi-centre randomised double-blind placebo-controlled trial was performed in patients scheduled for elective CT colonography. Patients were randomised to receive either a bolus of 7.5 μg/kg alfentanil (n = 45) or placebo (n = 45). The primary outcome was the difference in maximum pain during colonic insufflation on an 11-point numeric rating scale. We defined a clinically relevant effect as a maximum pain reduction of at least 1.3 points. Secondary outcomes included total pain and burden of CT colonography (5-point scale), the most burdensome aspect and side effects. Our primary outcome was tested using a one-sided independent samples t-test. Maximum pain scores during insufflation were lower with alfentanil as compared with placebo, 5.3 versus 3.0 (P  < 0.001). Total CT colonography pain and burden were also lower with alfentanil (2.0 vs. 1.6; P = 0.014 and 2.1 vs. 1.7; P = 0.007, respectively). With alfentanil fewer patients rated the insufflation as most burdensome aspect (56.1% vs. 18.6%; P = 0.001). Episodes with desaturations  < 90% SpO2 were more common with alfentanil (8.1% vs. 44.4%; P  < 0.001, but no clinically relevant desaturations occurred. A low-dose intravenous alfentanil bolus provides a clinically relevant reduction of maximum pain during CT colonography and may improve the CT colonography acceptance, especially for patients with a low pain threshold. Dutch Trial Register: NTR2902