Population pharmacokinetics of bupivacaine in combined lumbar and sciatic nerve block.

OBJECTIVES: The primary aim of this study was to establish the population pharmacokinetic (PPK) model of bupivacaine after combined lumbar plexus and sciatic nerve blocks and secondary aim is to assess the effect of patient's characteristics including age, body weight and sex on pharmacokinetic parameters. MATERIALS AND METHODS: A total of 31 patients scheduled for elective lower extremity surgery with combined lumbar and sciatic nerve block using plain bupivacaine 0.5% were included. The total bupivacaine plasma concentrations were measured before injection and after two blocks placement and at selected time points. Monitoring of bupivacaine was made by high performance liquid chromatography (HPLC) with ultraviolet detection. Non-linear mixed effects modeling was used to analyze the PPK of bupivacaine. RESULTS: One compartment model with first order absorption, two input compartments and a central elimination was selected. The Shapiro-Wilks test of normality for normalized prediction distribution errors for this model (P = 0.156) showed this as a valid model. The selected model predicts a population clearance of 930 ml/min (residual standard error [RSE] = 15.48%, IC 95% = 930 ± 282.24) with inter individual variability of 75.29%. The central volume of distribution was 134 l (RSE = 12.76%, IC = 134 ± 33.51 L) with inter individual variability of 63.40%. The absorption of bupivacaine in two sites Ka1 and Ka2 were 0.00462/min for the lumbar site and 0.292/min for the sciatic site. Age, body weight and sex have no effect on the bupivacaine pharmacokinetics in this studied population. CONCLUSION: The developed model helps us to assess the systemic absorption of bupivacaine at two injections sites.

Effects of intrathecal midazolam on postoperative analgesia when added to a bupivacaine-clonidine mixture.

BACKGROUND: Previous clinical and experimental studies have shown that a midazolam-clonidine mixture has a synergistic antinociceptive effect. This study evaluated the postoperative analgesic effect of adding midazolam to an intrathecal bupivacaine-clonidine mixture. METHODS: One hundred ten patients scheduled to undergo elective lower-extremity surgery were enrolled in this double-blind, randomized trial. Spinal anesthesia was administered by using 1 of 2 mixtures. Group B-C received 12.5 mg isobaric 0.5% bupivacaine, 30 mug clonidine, and 0.4 mL 0.9% saline. Group B-C-M received the B-C mixture plus 2 mg of midazolam in a 0.4-mL solution. Motor and sensory block levels were assessed before, during, and after the procedure until regression of the block to S2. Sedation levels were determined before anesthesia, during surgery, and at the end of the procedure. Postoperative analgesia was assessed every 15 minutes by using a visual analog scale. Duration of sensory and motor blocks was determined based on a modified Bromage scale, and time of the first pain relief request was noted. RESULTS: Duration of sensory block, time of first postoperative analgesic request, and amount of postoperative morphine administered were comparable between groups. However, the motor blockade lasted significantly longer in the B-C-M group compared with the B-C group (287 +/- 73 minutes vs 257 +/- 72 minutes, respectively; P < .05). CONCLUSION: Addition of midazolam to an intrathecal B-C mixture does not potentiate postoperative analgesia but prolongs the motor blockade.

Co-analgesic effect of ketorolac after thoracic surgery.

Thoracotomies are painful surgical procedures and adequate pain relief is associated with improved respiratory function and fewer respiratory complications. After thoracotomy for lung resection, patients received morphine-based patient-controlled analgesia (PCA). Three groups were prospectively and randomised investigated: patients receiving preemptive ketorolac, those given postoperative ketorolac and controls. No differences among groups were found for demographic data, anaesthesia and surgery durations, or for the amounts of anaesthesia drugs administered. The blood losses were also comparable: 565 +/- 374 ml for the preemptive ketorolac group. 749 +/- 491 ml for the postoperative ketorolac group and 674 +/- 323 ml for the controls. At 48 h after surgery, compared to controls, morphine consumption was 36% lower for the preemptive ketorolac group and 17% lower for postoperative ketorolac group (p < 0.05). No statistically significant differences were observed for pulmonary function tests. These results suggest that non-steroidal anti-inflammatory drugs can reduce the opioid requirements after thoracic surgery but do not improve lung function.

[Comparison of three protocols in the control of cardiovascular response to suspended laryngoscopy in ENT surgery]. / Comparaison de trois protocoles dans le contrôle de la réponse cardiovasculaire à laryngoscopie suspendue dans la chirurgie ORL.

The objective was to compare the effect of three pharmacological agents on the hemodynamic response to suspended laryngoscopy in micro ENT Surgery. Double blind randomised prospective study having included: groupe A (n = 16) having benefited before laryngoscopy of 150 mcg/kg esmolol, groupe B (n = 16) 15 mcg/kg of nicardipine, groupe C (n = 15) 1 mg/kg of lidocaine and groupe D (n = 16), placebo group. All groups were comparable for demographic and anesthetic data. A significant reduction of the heart rate and pressure rate product were noted in esmolol group during the endoscopic act and maintained until arousal. Whereas there was no difference in the blood pressure during the procedure whatever the pharmacological agent for prevention of cardiovascular complications for patients to risk in micro ENT surgery.