The effect of epidural lidocaine administration on sedation of propofol general anesthesia: a randomized trial.

STUDY OBJECTIVE: To examine the influence of epidural and intravenous (IV) lidocaine, and height of the epidural sensory block, on the dose of propofol required for induction of general anesthesia. DESIGN: Randomized controlled study. SETTING: University hospital. PATIENTS: 66 adult, ASA physical status 1 and 2 patients, aged 25 to 65 years, undergoing elective abdominal surgery. INTERVENTIONS: Patients were randomized to 4 groups: the epidural saline control group (Group C; L2-L3 puncture, epidural and IV saline), the IV lidocaine group (Group IV; L2-L3 puncture, saline epidural, IV lidocaine 1 mg/kg), the lumbar epidural lidocaine group (Group EL; L2-L3 puncture, 1.5% lidocaine epidural, IV saline), and the thoracic epidural lidocaine group (Group ET; T9-T10 puncture, 1.5%lidocaine epidural, IV saline). Two minutes after the beginning of the infusion of IV lidocaine or saline, propofol anesthesia was initiated. MEASUREMENTS: Mean arterial blood pressure (MAP), heart rate (HR), and sensory block height were monitored. The induction dose of propofol, its estimated effect-site concentration (Ce), and plasma concentration were measured at various time points. Finally, we recorded the time taken for the bispectral index (BIS) to decrease to 60, the plasma concentration of lidocaine at induction, and the occurrence of adverse events. The induction time (when BIS reached 60) also was recorded. MAIN RESULTS: The induction propofol dose, Ce, and plasma concentration of propofol when BIS equaled 60 were significantly lower in Group IV, Group EL, and Group ET than Group C. The above parameters in Group ET (T9 - T10 puncture) were significantly less than in Group EL (L2 - L3 puncture). The induction doses of propofol and plasma concentration of propofol and lidocaine were significantly higher in Group IV than in Groups EL or ET. CONCLUSIONS: Epidural and IV lidocaine reduce the dose of propofol required to induce general anesthesia. Administration of lidocaine via the epidural route reduces anesthetic requirements more so than the IV route. Propofol requirements were further reduced in patients with higher sensory epidural block.

Low doses of esmolol and phenylephrine act as diuretics during intravenous anesthesia.

INTRODUCTION: The renal clearance of infused crystalloid fluid is very low during anaesthesia and surgery, but experiments in conscious sheep indicate that the renal fluid clearance might approach a normal rate when the adrenergic balance is modified. METHODS: Sixty females (mean age, 32 years) undergoing laparoscopic gynecological surgery were randomized to control group and received only the conventional anesthetic drugs and 20 ml/kg of lactated Ringer's over 30 mins. The others were also given an infusion of 50 µg/kg/min of esmolol (beta1-receptor blocker) or 0.01 µg/kg/min of phenylephrine (alpha1-adrenergic agonist) over 3 hours. The distribution and elimination of infused fluid were studied by volume kinetic analysis based on urinary excretion and blood hemoglobin level. RESULTS: Both drugs significantly increased urinary excretion while heart rate and arterial pressure remained largely unaffected. The urine flows during non-surgery were 43, 147, and 176 ml in the control, esmolol, and phenylephrine groups, respectively (medians, P<0.03). When surgery had started the corresponding values were 34, 65 and 61 ml (P<0.04). At 3 hours, averages of 9%, 20%, and 25% of the infused volume had been excreted in the three groups (P<0.01). The kinetic analyses indicated that both treatments slowed down the distribution of fluid from the plasma to the interstitial fluid space, thereby preventing hypovolemia. CONCLUSIONS: Esmolol doubled and phenylephrine almost tripled urinary excretion during anesthesia-induced depression of renal fluid clearance.

[Anesthetic management of Stanford type A aortic dissection operation].

OBJECTIVE: To explore the anesthetic management experiences of patients with Stanford A aortic dissection undergoing surgical treatment through moderate or deep hypothermia circulatory arrest (DHCA). METHODS: From June 2008 to December 2011, a total of 77 patients undergoing surgical treatment of Stanford A aortic dissection was recruited. RESULTS: Cardiopulmonary bypass (CPB) was established under general anesthesia in all patients. The procedures included moderate hypothermia (n = 51) and DHCA (n = 26). The total surgical duration was 152 - 600 (292 ± 91) min, CPB time 38 - 310 (128 ± 43) min and aortic cross-clamp time 31 - 169 (87 ± 26) min. The time of circulatory arrest under deep hypothermia was 20 - 113 (41 ± 19) min in 26 patients. Among 77 patients, there were 5 intraoperative and 7 postoperative fatalities. The remained 65 patients were discharged postoperatively and received a regular outpatient follow-up. None of them died or required reoperation. CONCLUSION: Surgical treatment is appropriate and efficient for the patients with Stanford A aortic dissection. During surgery, the keys of preventing neurological complications are blood volume monitoring and blood protection.