Local cerebral blood flow, local cerebral glucose utilization, and flow - Metabolism coupling during sevoflurane versus isoflurane anesthesia in rats

Background Compared to isoflurane, knowledge of local cerebral glucose util ization (LCGU) and local cerebral blood flow (LCBF) during sevoflurane anes thesia is limited, Methods: LCGU, LCBF, and their overall means were measured in Sprague-Dan l ey rats (8 groups, n = 6 each) during sevoflurane and isoflurane anesthesia , 1 and 2 MAC, and in conscious control animals (2 groups, n = 6 each) usin g the autoradiographic 2-[C-14]deoxy-D-glucose and 4-iodo-N-methyl[C-14]ant ipyrinc methods. Results: During anesthesia mean cerebral glucose utilizati on was decreased:control 56 +/- 5 mu mol 100 g(-1) min(-1); 1 MAC isofluran e, 32 +/- 4 mu mol 100 g(-1) min(-1) (-43%); 1 MAC sevoflurane, 37 +/- 5 mu mol 100 g(-1) min(-1) (-34%); 2 MAC isoflurane, 23 +/- 3 mu mol. 100 g(-1) min(-1) (- 58%); 2 MAC sevoflurane, 23 +/- 5 mu mol 100 g(-1) min(-1) (-59% ). Local analysis showed a reduction In LCGU in the majority of the 40 brai n regions analyzed. Mean cerebral blood flow was increased as follows: cont rol 93 +/- 8 mi 100 g(-1) min(-1); 1 MAC isoflurane, 119 +/- 19 ml 100 g(-1 ) min(-1) (+28%); 1 MAC sevoflurane, 104 +/- 15 ml 100 g(-1) min(-1)(+12%); 2 MAC isoflurane, 149 +/- 17ml 100 g(-1) min(-1) (+60%); 2 MAC sevoflurane , 118 +/- 21 mi 100 g(-1) min(-1) (+27%). LCBF Tvas increased in most brain structures investigated. Correlation coefficients obtained for the relatio nship between LCGU and LCBF were as follows: control 0.93; 1 MAC isoflurane , 0.89; 2 MAC isoflurane, 0.71; 1 MAC sevoflurane, 0.83; 2 MAC sevoflurane, 0.59). Conclusion: Mean and local cerebral blood flows were lower during sevoflura ne than during Isoflurane anesthesia. This difference cannot be explained b y differing changes in glucose utilization because glucose utilization was decreased to the same extent in both groups.