Propofol is a relatively new intravenous anesthetic agent, and the cerebral blood flow (CBF) response to changes in PaCO2 during propofol anesthesia has not been extensively studied. The purpose of this study was to investigate the effects of propofol anesthesia on the CBF response to changes in PaCO2 in dogs.

In six dogs, after surgical preparation for posterior sagittal sinus outflow method, loading dose of propofol 5~6 mg/kg was injected and then anesthesia was maintained with a propofol infusion of 20 mg . kg-1 . hr-1 during study. Ventilation was controlled to hypocapnia(PaCO2 20~35 mmHg), normocapnia(PaCO2 35~45 mmHg) and hypercapnia(PaCO2 45~60 mmHg) by adjustment of minute ventilation. Posterior sagittal sinus blood flow was measured by metered syringe and then CBF was calculated. Cerebral metabolic rate for oxygen(CMRO2) was calculated with arterial and sagittal sinus blood analysis.

CBF at normocapnia (PaCO2 41±5 mmHg) was 28.7±11.6 ml . 100 g-1 . min-1 which increased to 46.5±14.4 ml . 100 g-1 . min-1 and decreased to 22.1±8.9 ml . 100 g-1 . min-1 on increasing PaCO2 (63±18 mmHg) and decreasing PaCO2 (33±3 mmHg), respectively. The slope of CBF versus PaCO2 was 1.29 ml . 100 g-1 . min-1 . mmHg. Blood pressure, herat rate, PaO2, CMRO2 were not changed between groups.

CBF response to changes in PaCO2 during propofol anesthesia is maintained and the slope of the CBF-CO2 response is similar to that found during anesthesia with other intravenous agents such as thiopental, midazolam, etomidate, opioids.