The radial hyperaemic response: a new and objective assessment of ulnar collateral supply to the hand.

The assessment of adequate ulnar collateral supply to the hand is mandatory prior to the harvest of the radial artery as a conduit for coronary artery bypass grafting. However, there is currently no one test which is widely used in all centres. We report a new and objective method of assessing ulnar collateral supply to the hand prior to harvest of the radial artery. This technique involves assessing the presence of a hyperaemic flow response to occlusion of the radial artery using an intraoperative transit time flowmeter. We found this technique to be objective and reliable, and would advocate its use in patients with a positive Allen's test.