Effect of mild hypothermia on cerebral oxygen metabolism in a rat model of chronic cerebral hypoperfusion and reperfusion / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of mild hypothermia on cerebral oxygen metabolism in a rat model of chronic cerebral hypoperfusion and reperfusion. Methods Twelve healthy SD rats weighing 170-210 g were randomly divided into normal body temperature group (group NT, n = 6) and mild hypothermia group (group MH, n = 6). Arterio-venous fistula was established by end-to-end anastomosis between the right common carotid artery and right external jugular vein according to Yassari. Mild hypothermia was induced in group MH before reperfusion and maintained for 3 h. The rectal temperature was reduced to 32 ℃ while in group NT rectal temperature was maintained at about 37 ℃ . Cerebral blood perfusion (CBP) was assessed by using a lasser Doppler perfusion image system before reperfusion (T_1), immediately after reperfusion (T_2) and 24 h after reperfusion (T_3). Venous and arterial blood samples were collected from superior sagittal sinus and femoral artery respectively for blood gas analysis at T_(1-3) . Cerebral arterial venous O_2 saturation difference (Sa-vO_2), cerebral O_2 extraction rate (CERO_2) and cerebral arterial-venous lactic acid concentration difference ( Da-vL) were calculated. Results In NT group left CBP was significantly decreased at T_2 as compared with the baseline value at T_1 , while at T_3 bilateral CBP was decreased. In MH group bilateral CBP was significantly decreased at T_2 but returned to baseline level at T_3. CERO_2 was significantly decreased at T_2 as compared with the baseline value at T_1 in MH group. Da-vL was significantly increased at T_3 in NT group. Compared with group NT, bilateral CBP was significantly decreased, CERO_ and Da-vL were significantly decreased at T_2 ,while no significant change was found in Sa-vO_2 in group MH. Conclusion Mild hypothermia is beneficial for the balance of cerebral oxygen metabolism in the rats with chronic cerebral hypoperfusion and reperfusion.