Monitoring of brain metabolism during aneurysm surgery using microdialysisand brain multiparameter sensors

The aim of the study was to monitor brain metabolism during aneurysm clippi ng using microdialysis and multiparameter sensors, particularly to investig ate the effects of temporary clipping of vessels. Microdialysis catheters ( n = 10) and Paratrend brain multiparameter (O-2, CO2, pH and temperature) s ensors (n = 15) were inserted into the cerebral cortex via a specially desi gned triple bolt prior To craniotomy. Baseline brain O-2 levels ranging fro m 15-45 mmHg (2.0-6.0 kPa) and glucose levels from 0.5-3 mmol l(-1) were st able during uneventful periods. The mean lactate/pyruvate (L/P) ratio range d from 32 to 65 (normal < 30), indicating a tendency towards anerobic metab olism in all patients. Overall, short periods of temporary clipping (< 3 mi n; n = 6) were well tolerated producing no significant reduction in brain O -2 (pre-clip mean 23 mmHg (3.0 kPa) vs. post-clip mean 20 mmHg (2.6 kPa)) o r elevation of the UP ratio (pre-clip mean 42 vs, post-clip mean 43). Two p atients with prolonged temporary clipping showed derangements in the Paratr end parameters associated with increases in the UP ratio. The results demon strated that the monitored variables remained stable during uneventful proc edures, including transient temporary clipping, but adverse events such as prolonged temporary clipping resulted in pronounced changes in brain metabo lism. Monitoring of metabolism during aneurysm surgery may be of benefit in selected patients.