Objective To investigate the serum therapeutic concentration of tramadol during intravenous analgesia for postoperative pain relief. Methods Twenty adult patients ASA Ⅰ-Ⅱ (10 male, 10 female) undergoing elective radical operation for cancer of stomach were treated with intravenous tramadol for postoperative pain relief. Patients addicted to any drug or tolerant to opioid and patients with epilepsy or liver and/or renal dysfunction were excluded. All patients were premedicated with intramuscular phenobarbital 0.1g and atropine 0.5mg. Anesthesia was induced with midazolam 0. 1mg/kg and fentanyl 5 μg/kg and intubation was facilitated with vecuronium 0.16mg/kg. Anesthesia was maintained with continuous intravenous infusion of propofol 4-6 mg@ kg 1 @ h 1, fentanyl 2-3 μg@ kg-1 @ h-1 and vecuronium 0.1mg@ kg-1@ h-1 combined with inhalation of 1% isoflurane. After surgery in ICU when patients felt slight pain (VAS 1-2), intravenous tramadol 1.5mg/kg was given as initial dose. Whenever patients felt slight pain (VAS 1-2) again, a bolus of tramadol 20 mg was given intravenously every 10 min until VAS was 0. The onset time (from the end of iv injection of initial dose of tramadol to VAS 0), the duration of action (from VAS 0 to VAS 1-2) and the time when accumulated dose of tramadol amounted to twice the initial dose were recorded. HR, MAP, respiratory rate (RR) and SpO2 were monitored and recorded before and 10, 20, 30 min after administration of tramadol. Venous blood samples were taken before each additional tramadol administration on demand for determination of serum tramadol concentration by high performance liquid chromatography. Results The mean serum therapeutic level of tramadol during period of analgesia was (370±148)ng/ml(248.6-615.7ng/ml). The mean onset time of the initial dose was (9.2± 2.1 )min. The mean duration of action was (2.3 ± 1.0)h. The time when accumulated dose of tramadol amounted to twice the initial dose was (6.4 ± 2.7)h on average. There were no significant changes in HR,MAP, RR and SpO2 after tramadol. Conclusions It is safe and effective to give intravenous tramadol for postoperative pain relief. Serum therapeutic concentration of tramadol varies greatly from patient to patient,so the dose of tramadol should be individulized.[Key Words] Pain, postoperative; Tramadol; Plasma concentration; Injections, intravenous

Objective To examine pharmacodynamics and serum concentration of tramadol during continuous intravenous infusion for postoperative pain relief Methods 500 ASA Ⅰ Ⅱ patients undergoing operation on extremities, spine or abdomen under anesthesia were studied Premedication included phenobarbital 0 1g and atropine 0 5mg im Anesthesia was induced with midazolam 0 08 0 12mg?kg -1 , fentanyl 5 6?g?kg -1 and vecuronium 0 12 0 14 mg?kg -1 and maintained with continuous intravenous infusion of propofol 3 0 4 5 mg?kg -1 ?h -1 , fentanyl 2 8 3 4?g?kg -1 ?h -1 and vecuronium 0 06 0 08 mg?kg -1 ?h -1 supplemented with inhalation of 0 8% 1 0% isoflurane At the end of operation a loading dose of tramadol 1 5 mg?kg -1 was given intravenously over 2 min, followed by continuous intravenous infusion of tramadol for 72h The patients were divided into two groups: group Ⅰ (n=246) received tramadol intravenous infusion at a rate of 8mg h -1 and group Ⅱ (n=254) received tramadol infusion at a rate of 10mg h -1 Venous blood samples were taken from 10 patients in group Ⅱ at 0, 0 5, 1, 3, 6, 12, 24, 30, 42, 48, 54, 60, 72h during postoperative tramadol infusion for determination of serum concentration of tramadol by high performance liquid chromatography (HPLC) Efficacy of analgesia was assessed by VAS score and side effects were recorded Results The two groups were comparable with regard to age, sex, weight, types of operation and the amount of fentanyl used during operation There was significant difference in the mean VAS scores between group Ⅰ (1 16?1 15) and group Ⅱ (0 83?1 33) (P

ObjectiveTo evaluate the clinical effects of early pain intervention provided by an acute pain service team on the efficacy of postoperative patient-controlled analgesia ( PCA).MethodsOne thousand four hundred and sixty-seven patients receiving postoperative PCA in November and December 2011 were enrolled in this study.Patients were excluded from the study if they were ＜ 12 yr,unconscious or uncoorperative.The patients were divided into control group (group C,n =725) and intervention group (group 1,n =742).Group 1 received preoperative systematic pain education on the significance and conect use of PCA including pharmacology of analgesic (sufentanil 100 μg in normal saline 100 ml) by an acute pain service team made up of anesthesiologists and nurses specializing in pain management.The education was repeated immediately before operation and when the patients were discharged from recovery room.While in grup C the correct use of PCA was explained routinely before operation by anesthesiologists and nurses taking care of the patients.The incidence of incomplete analgesia and adverse reactions and patient' s satisfaction were rated.ResultsThe incidence of incomplete analgesia was significantly lower and the patient's satisfaction higher in group 1 than in control group.There was no significant difference in adverse reactions between the two groups.ConclusionEarly pain intervention provided by an acute pain service team is effective in improving the efficacy of postoperative PCA and patient's satisfaction.