The utility of intraoperative blood flow measurement during aneurysm surgery using an ultrasonic perivascular flow probe

OBJECTIVE: Inadvertent vessel compromise is one major cause of unfavorable outcome from aneurysm surgery. Existing strategies for intraoperative assessment of this complication have potential limitations and disadvantages. We assessed the utility of quantitative intraoperative flow measurements using the Transonic ultrasonic flow probe (Transonic Systems, Inc., Ithaca, NY) during aneurysm surgery. METHODS: Of all aneurysms treated surgically at our institution from 1998 to 2003, 103 patients with 106 aneurysms were identified in whom intraoperative flow measurements were available for analysis. We assessed the frequency of flow compromise and clip repositioning and correlated these with postoperative angiography and stroke. RESULTS: Significant (> 25%) reduction in flow rate was apparent in 33 (31.1%) cases, and resulted in clip repositioning in 27 (25.5%), with return to baseline flow except for two cases with vessel thrombosis/dissection. In the other six cases, flow reduction was owing to spasm resolving with papaverine (n = 3) or responded to retractor repositioning (n = 3). In another six (5.7%) cases, unnecessary clip repositioning was avoided (n = 3) or safe occlusion of the parent vessel for trapping of the aneurysm was allowed by confirming adequate distal flow (n = 3). Aneurysms of the basilar, middle cerebral, anterior communicating, or carotid terminus were more likely to be associated with flow compromise (odds ratio, 4.3; P = 0.03). Postoperative angiography corroborated vessel patency in all cases, and no unexpected large vessel occlusions or strokes were evident. CONCLUSION: Use of the ultrasonic flow probe provides real-time immediate feedback concerning vessel patency. Vessel compromise is easier to interpret than with Doppler, and faster/less invasive than intraoperative angiography. Intraoperative flow measurement is a valuable adjunct for enhancing the safety of aneurysm surgery