Continuous Monitoring of Regional Cortical Blood Flow in Aneurysm Surgery

ABSTRACT

OBJECTIVE: The tolerance and the safety of temporary arterial occlusion in aneurysm surgery are variable among patients because of individual variations of their collateral circulation. We recorded continuous intraoperative regional cortical blood flow(rCoBF) with thermal diffusion flowmetry(TDF) in patients with aneurysmal subarachnoid hemorrhage to determine a safe time limit for temporary occlusion in relation to rCoBF. PATIENTS AND METHODS: From Oct. '97 to Sep. '98, 40 patients with cerebral aneurysm at anterior cerebral artery(ACA) or middle cerebral artery(MCA) were included in this study. The TDF probe was placed over the cortex which was supplied by corresponding arteries. For data analysis, we included only the patients with Hunt-Hess grade I or II on admission. RESULTS: The total occlusion time of the proximal parent artery in 24 patients was on average 21.8 minutes, ranging between 9 minutes and 68 minutes. The lowest rCoBF in relation to temporary occlusion time in patient with excellent outcome was as follows 0ml/100mg/min for 13 minutes and 6ml/100mg/min(11% of basal rCoBF) for 18 minutes in the middle cerebral artery and bilateral anterior cerebral arteries, respectively. The multiple regression equation regarding safe time for temporary clipping was as follows safe time = 5.5 + 0.06 X rCoBF intra + 0.25 X rCoBF pre. And reperfusion time for the full recovery of rCoBF was within 4 minute in most cases, except some no-reflow cases. CONCLUSION: In our study with proper brain protection, a safe time limit for temporary occlusion was calculated 18 minutes even at 0ml/100mg/min in the MCA and this technique seems to be very useful to detect a continuous real time change of rCoBF during aneurysm surgery.