Effects on Cerebral Oxygen Balance in Coronary Artery Bypass Grafting: A Comparison of Conventional and Minimal Extracorporeal Circulation

Objective: To investigate the cerebral oxygen balance difference between minimal extracorporeal circulation (MECC) and conventional extracorporeal circulation (CECC) during coronary artery bypass grafting. Methods: 20 patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CPB) were divided into two groups, the CECC group (n=10) and the MECC group (n=10). Blood withdrawn from radial artery and right jugular vein were analyzed at the following timepoints: during the anesthesia induction (T1), before CPB (T2), the initiation of CPB (T3), aorta crossclamped (T4), after temperature decreased (T5), during stable hypothermia (T6), initiation of rewarming (T7), aorta unclamped (T8), after weaning of CPB (T9), end of the operation (T10).The artery oxygen content (CaO2 ) and cerebral oxygen extraction ratio (OER) were calculated. The mean artery pressure (MAP), hemoglobin (Hb), nasopharyngeal temperature (NPT), and pump perfusion flow were recorded during the operation. Results: (1) MAP and Hb of MECC group were significantly higher than those in the CECC group from T3 to T10 (P<0.05); perfusion flow in MECC group during CPB was significantly lower than those in CECC group (P<0.05); NPT in MECC group was significantly higher than those in CECC group (P<0.05). (2) During T3-T4 and T8-T9, jugular venous oxygen saturation in CECC group was significantly lower than those in MECC (P<0.05); OER in CECC group was significantly higher than those in MECC group (P<0.05). (3) The arterial lactic acid and venous lactic acid in these two groups were decreased gradually from T3 to T10. Thearteriovenous difference in lactic acid in CECC group were higher than those in MECC group during T3-T4 and T8-T9 (P<0.05). Conclusion: Patients undergoing coronary artery bypass grafting with MECC enjoy more stable blood pressure, less intense hemodilution and lighter temperature disturbance than those with CECC, which indicating a better cerebral oxygen balance in CABG.

Effects of Increasing Concentrations of Propofol on Jugular Venous Bulb Oxygen Saturation in Neurosurgical Patients under Normothermic and Mildly Hypothermic Conditions

Background Recent evidence suggested that propofol can deteriorate the cerebral oxygen balance compared with inhalational anesthetics. However, dose-related influences of propofol on cerebral oxygen balances were not clearly investigated. In the current study, the authors investigated the effects of increasing concentrations of propofol on jugular venous bulb oxygen saturation (Sj(O2)) in neurosurgical patients under normothermic and mildly hypothermic conditions. Methods After institutional approval and informed consent were obtained, 30 adult patients undergoing elective craniotomy were studied. Patients were randomly allocated to either normothermic or hypothermic group (n = 15 in each group). In the normothermic and hypothermic groups, tympanic membrane temperature was maintained at 36.5 degrees and 34.5 degrees C, respectively. Sj(O2) was measured at predicted propofol concentrations of 3, 5, and 7 microg/ml using a target-controlled infusion system in both groups. Results At a predicted propofol concentration of 3 microg/ml, there were no significant differences in Sj(O2) values between the normothermic and hypothermic groups, although the incidence of desaturation (Sj(O2) &lt; 50%) was significantly higher in the normothermic group than in the hypothermic group (30% vs. 13%; P &lt; 0.05). Sj(O2) values and the incidence of desaturation remained unchanged during the changes in predicted propofol concentration from 3 to 7 microg/ml both in the normothermic and hypothermic groups. Conclusion The results indicated that the increasing concentrations of propofol did not affect Sj(O2) values in neurosurgical patients under normothermic and mildly hypothermic conditions.