Cerebral blood volume and blood flow at varying arterial carbon dioxide tension levels in rabbits during propofol anesthesia

There are Little data on the effects of propofol on cerebral blood volume ( CBV). We studied the effects of changes in Paco(2) on CBV and cerebral bloo d flow (CBF) during propofol anesthesia in eight New Zealand white rabbits. We also investigated the effects of propofol over time on CBV and CBF duri ng normocapnia (control group). At normocapnia, the mean (+/- SD) CBV and C BF values were 2.41 +/- 0.68 mL/100 g and 56 +/- 28 mL/100 g/min, respectiv ely,. When Paco(2) was reduced from 41 to 27 mm Hg, no significant change i n either CBV or CBF was observed (P > 0.10). However, increasing Paco(2) fr om 41 to 58 mm Hg resulted in a 30% increase in CBV (3.08 +/- 0.86 mL/100 g , P < 0.05) and a 91% increase in CBF (97 +/- 39 mL/100 g/min, P < 0.01). I n the control group, there were no significant changes in CBV and CBF (P > 0.10) during 2 h of propofol anesthesia. These results indicate that, durin g propofol anesthesia, cerebrovascular reactivity of blood flow and blood v olume is maintained during hypercapnia but is markedly diminished during hy pocapnia.