Objective To study the influence of lidocaine on the propofol concentration effect relationships for loss of eyelash reflex and loss of consciousness,hemodynamic function Methods Thirty eight patients were randomly allocated to receiving a computer controlled infusion of lidocaine at target concentration of 0?g?ml -1 (group A,n=9),1 25?g?ml -1 (group B,n=7), 2 5?g?ml -1 (group C,n=7), 5?g?ml -1 (group D,n=8),or 7?g?ml -1 (group E,n=7) respectively While the target concentration of lidocaine was kept stable, propofol was administrated with a computer controlled infusion at an initial target concentration of 0 5 1?g?ml -1 , which was increased every time by 0 5?g?ml -1 until loss of consciousness Plasma concentrations of lidocaine and propofol were measured with high performance liquid chromatography Results 50% of patients lost eyelash reflex and consciousness at plasma propofol concentrations(Cp50) of 1 78 and 3 17?g?ml -1 in the absence of lidocaine In the presence of plasma lidocaine concentration of 1 25 4 3 ?g?ml -1 ,the Cp50 for loss of eyelash reflex was reduced by 42 1% There was a linear regression relationship between plasma lidocaine concentrations from 0 to 7?g?ml -1 and the Cp50 for loss of consciousness (r=-0 69 ) Conclusions The Chinese Cp50 for loss of eyelash reflex and consciousness are lower than those reported abroad Plasma lidocaine concentration at 4?g?ml -1 can potentiate properly the potency of propofol on the sedation and hypnosis during anesthesia induction

Objective To evaluate the effects of fentanyl and lidocaine on hypnotic effect of propofol in total intravenous anesthesia(TIVA) Methods One hundred and sixty ASAI Ⅲ patients(86 male,74 female) aged (55 0?12 4)yr,weighing (58 0?9 8)kg,scheduled for elective surgery were randomly divided into propofol group(group P,n=30), propofol fentanyl group(group PF,n=52) and propofol lidocaine group (group PL,n=78) Patients with kidney and liver dysfunction, hypertension, neurological and mental disease were excluded All patients were premedicated with intramuscular phenobarbital 0 1g and atropine 0 5mg BP,HR,SpO 2 and BIS were continuously monitored The patients were anesthetized by TIVA with TCI The target plasma concentration for fentanyl was 2?g/L(group PF) and for lidocaine 4mg/L(group PL) The initial target plasma concentration of propofol was set at 1mg/L When pre set concentration was reached, target propofol plasma concentration was increased by increments of 0 5mg/L until loss of consciousness Blood samples were taken before anesthesia(T 0), loss of consciousness(T 1), immediately after intubation(T 2), at skin incision(T 3), 5 and 10 min after skin incision(T 4,T 5), when TIVA was ended (T 6) and when the patient waked up(T 7) for determination of plasma concentrations of propofol, fentanyl and lidocaine Results ED 90 and ED 50 of propofol for loss of consciousness were lower in group PF and PL than those in group P but the difference was of no statistical significance (P