[Prostagrandin E1-induced hypotension well maintains cerebral circulation and carbon dioxide reactivity in non-neurosurgical patients under sevoflurane-anesthesia].

To evaluate the effect of prostagrandin E1 (PGE1)-induced hypotension on cerebral blood flow (CBF) and carbon dioxide (CO2) reactivity of CBF, regional cerebral hemoglobin oxygen saturation (rSo2) was measured in non-neurosurgical patients (n = 10) under sevoflurane-anesthesia using near infrared spectroscopy. PGE1 was infused intravenously to maintain arterial pressure at a level of about 75% of the MAP (hypotensive group) under sevoflurane-anesthesia alone (normotensive group). Ventilation was controlled to adjust PaCO2 to hypocapnia (25-30 mmHg), normocapnia (35-40 mmHg) and hypercapnia (45-50 mmHg) in both normotensive and hypotensive groups. rSo2 during hypotension did not change by hypocapnia and normocapnia, but significantly increased by hypercapnia, compared with rSo2 during normotension. Significant correlations between rSo2 and PaCO2 during both normotensive and hypotensive groups were observed. Slope of the regression line of rSo2 and PaCO2 did not differ between the normotensive and hypotensive groups. When arterial oxygen content and cerebral metabolic rate of oxygen are constant, changes in rSo2 correlate with those of CBF. Therefore, CBF and CO2 reactivity of CBF that indicates autoregulation in response to changes in CO2 during hypotension were maintained as those during normotension. The results show that PGE2-induced hypotension maintains CBF and CO2 reactivity well in non-neurosurgical patients under sevoflurane anesthesia.