Measurement of ulnar flow is helpful in predicting ischemia after radial artery harvest.

Background: Despite a negative Allen test, some patients develop hand ischemia after radial artery harvesting. The presence of large interosseous collaterals may reduce the sensitivity of Allen test. To evaluate the combination of ulnar flow measurements and the Allen test as an effective screening technique, we performed Doppler ultrasonography during Allen's maneuver. Methods: The Allen test was used to select candidates for harvesting radial artery from 80 patients undergoing coronary bypass surgery. Results: Of 71 patients with a negative Allen test, one patient developed hand ischemia. This patient was one of six (7.5 %) possessing low ulnar flow levels (less than 40 ml/min/m2 during compression of the radial artery). This low-flow group had a higher risk for ischemia of the 71 patients with a negative Allen test. The post-operative flow differed greatly from the pre-operative flow in eight patients (11.3 %), which was likely due to large sacrificed interosseous collaterals. Conclusion: Combined use of ulnar flow measurement with the Allen test appears to increase the sensitivity of the Allen test. Neither test, however, is sufficient for a group of patients with large interosseous collaterals.