Effects Of Target Controlled Infusion Of Propofol On Amino Acid Of Intracranial Venous Blood And Cerebral Oxygen Metabolism During Rewarming Period Of Cardiopulmonary Bypass

Objective To observe the changes of amino acid of intracranial venous blood and theirinfluences to cerebral oxygen metabolism at different phase point of propofol given bytarget-controlled infusion(TCI) during mild hypothermic cardiopulmonary bypass (CPB).Toevaluate cerebral protective effects of target-controlled of propofol during rewarming periodof CPB.Methods Forty consecutive ASAâ…¡-â…¢patients undergoing elective cardiac surgeryunder mild hypothermic CPB were randomly divided into 2 groups: in group A the patientswere given target controlled of proprfol (1～2μg.ml^-1), in group B the patients were givenmidazolam 0.10～0.20mg.kg^-1.h^-1. SNAP index (SI) was maintained at 60±5 byadjustment)simultaneously from radial artery and internal jugular vein at the time of 5rainafter anesthesia induction (T1),5min after beginning of CPB(T2),5min after hypothermiaover (T3) and at the time of nasopharyngeal temperature (NPT) reaching the point of 37℃0min(T4), 30min(T5) and 60min (T6).All of samples were measured blood gas, glucose(G)and lactic acid(L). According Hb, SaO₂, SjvO₂, PaO₂, PjvO₂, La, Ljv, Ga, Gjv to calculatearterial oxygen content(CaO₂), jugular vein oxygen content(CjvO₂), arterial- vein oxygencontent difference (AVDO₂), oxygen extraction rate(CEO₂), lactate oxygen index(LOI),arterial-vein lactate difference(AVDL), cerebral lactate production(CLP), arterial-veinglucose difference(AVDG), glucose extraction rate(CGU).The jugular venous blood wasmeasured Glutamic acid(Glu),γ-amino butyric acid(GABA) and Glycine(Gly).Theexcitotoxin index(EI) was calculated.All the above indexes were analyzed by statistics.Result (1) Cerebral oxygenation: the significant differences of SjvO₂,CjvO₂,CaO₂,AVDO₂ and CEO₂ were not seen between group A and group B (P＞0.05). LOI washigher in group B than those in group A at T4,T5,T6(P＜0.01). (2) Cerebral oxygenmetabolism: the significant differences of Ga,Gjv,AVDG,CGU were not seen betweengroup A and group B (P＞0.05). La,Ljv,AVDL,CLP were higher in group B than thosein group A at T4,T5,T6(P＜0.05 or 0.01). (3)Amino acid of intracranial venous blood: Glu were higher in group B than those in group A at T4,T5,T6(P＜0.01). Gly was higher ingroup A than that in group B at T4(P＜0.01). GABA were higher in group A than those ingroup B at T4,T5,T6(P＜0.01). EI were higher in group B than those in group A atT4,T5,T6(P＜0.01).Conclusion The study shows that target-controlled of propofol (1～2μg.ml^-1) canameliorate cerebral oxygen metabolism,inhibit excitory amino acid and plays a role in thecerebral protection during rewarming period of cardiopulmonary bypass.