Joël L’Hermite

A comparison of the pharmacodynamics and pharmacokinetics of bupivacaine, ropivacaine (with epinephrine) and their equal volume mixtures with lidocaine used for femoral and sciatic nerve blocks: a double-blind randomized study.

BACKGROUND: Mixtures of lidocaine with a long-acting local anesthetic are commonly used for peripheral nerve block. Few data are available regarding the safety, efficacy, or pharmacokinetics of mixtures of local anesthetics. In the current study, we compared the effects of bupivacaine 0.5% or ropivacaine 0.75% alone or in a mixed solution of equal volumes of bupivacaine 0.5% and lidocaine 2% or ropivacaine 0.75% and lidocaine 2% for surgery after femoral-sciatic peripheral nerve block. The primary end point was onset time. METHODS: In a double-blind, randomized study, 82 adults scheduled for lower limb surgery received a sciatic (20 mL) and femoral (20 mL) peripheral nerve block with 0.5% bupivacaine (200 mg), a mixture of 0.5% bupivacaine 20 mL (100 mg) with 2% lidocaine (400 mg), 0.75% ropivacaine (300 mg) or a mixture of 0.75% ropivacaine 20 mL (150 mg) with 2% lidocaine (400 mg). Each solution contained epinephrine 1:200,000. Times to perform blocks, onset times (end of injection to complete sensory and motor block), duration of sensory and motor block, and morphine consumption via IV patient-controlled analgesia were compared. Venous blood samples of 5 mL were collected for determination of drug concentration at 0, 5, 15, 30, 45, 60, and 90 min after placement of the block. RESULTS: Patient demographics and surgical times were similar for all four groups. Sciatic onset times (sensory and motor block) were reduced by combining lidocaine with the long-acting local anesthetic. The onset of bupivacaine-lidocaine was 16 ± 9 min versus 28 ± 12 min for bupivacaine alone. The onset of ropivacaine-lidocaine was 16 ± 12 min versus 23 ± 12 for ropivacaine alone. Sensory blocks were complete for all patients within 40 min for those receiving bupivacaine–lidocaine versus 60 min for those receiving bupivacaine alone and 30 min for those receiving ropivacaine–lidocaine versus 40 min for those receiving ropivacaine alone (P < 0.05). Duration of sensory and motor block was significantly shorter in mixture groups. There was no difference among groups for visual analog scale pain scores and morphine consumption during the 48 h postoperative period, except for bupivacaine alone (median: 9 mg) versus bupivacaine–lidocaine mixture (15 mg), P < 0.01. There was no difference in the incidence of adverse events among groups. Plasma concentrations of bupivacaine and ropivacaine were higher, and remained elevated longer, in patients who received only the long-acting local anesthetic compared to patients who received the mixture of long-acting local anesthetic with lidocaine (P < 0.01). CONCLUSION: Mixtures of long-acting local anesthetics with lidocaine induced faster onset blocks of decreased duration. Whether there is a safety benefit is unclear, as the benefit of a decreased concentration of long-acting local anesthetic may be offset by the presence of a significant plasma concentration of lidocaine.

Ophthalmic regional anesthesia: medial canthus episcleral (sub-tenon) single injection block.

BackgroundThe purpose of this study was to evaluate the efficacy and safety of episcleral single-injection anesthesia in a large number of patients. MethodsOver a period of 5 yr, in four institutions, anesthesiologists involved in this prospective study completed a standardized form to evaluate single-injection medial canthus high-volume episcleral anesthesia. The success rate of the block was rated according to an akinesia score. The study parameters included demographic data, surgical procedure, and anesthetic management. All patients were followed up at least until postoperative day 1, and all complications, pain, and discomfort were noted. Statistical analysis was done to assess the risk factors for complications. ResultsA total of 2,031 patients were included in the study. The most frequent surgical procedures performed were phacoemulsification and posterior chamber artificial lens implantation (91.0%). A total of 66 complications (3.3%) occurred in 60 patients. One patient had a retrobulbar hemorrhage, and 59 had one or two more minor incidents or pain/discomfort with the procedure. The complications consisted of subconjunctival hematoma (1.3%), ocular hypertonia (0.4%), and chemosis (0.30%). Statistical analysis revealed that inexperience in the technique represented a risk factor for complications. ConclusionsThis is the first survey of a large experience in episcleral single-injection anesthesia, a form of anesthesia that does not preclude sharp-needle complications and does require training. Only one complication occurred among 2,031 patients; however, a larger number of patients is needed to definitively evaluate the safety of episcleral single-injection anesthesia.

Caruncle single injection episcleral (Sub-tenon) anesthesia for cataract surgery: mepivacaine versus a lidocaine-bupivacaine mixture.

UNLABELLED We compared the quality of anesthesia provided by mepivacaine 2% or a mixture of lidocaine 2%-bupivacaine 0.5%, both with hyaluronidase, in caruncle single-injection episcleral (sub-Tenon) anesthesia. Sixty patients undergoing cataract surgery were included in this randomized, double-blinded study. The time to the onset of blockade, maximal akinesia, need for supplemental injection, and time to recovery were recorded. With mepivacaine, the time to onset was slightly shorter, and the akinesia score higher, than with the mixture. Although statistically significant, these differences are small. With mepivacaine, the time to recovery was shorter. We conclude that the reproducible short duration of the block may be an advantage in outpatient surgery. IMPLICATIONS We compared the classic mixture of lidocaine 2% plus bupivacaine 0.5% to mepivacaine 2% for caruncle episcleral (sub-Tenon) anesthesia for cataract surgery. Mepivacaine provided a more efficient block with a quicker onset and a quicker recovery. However, these differences were very small and were of little clinical interest.

Stroke volume optimization after anaesthetic induction: An open randomized controlled trial comparing 0.9% NaCl versus 6% hydroxyethyl starch 130/0.4

OBJECTIVE Postinduction hypotension during general anaesthesia could be corrected by a rapid cardiac preload optimization by fluid infusion. The type of fluid to be used in this context remains debated. The aim of our study was to compare the amount of fluid challenges required to optimize stroke volume after induction of anaesthesia with colloid (HES) or crystalloid (0.9% NaCl). DESIGN Open randomized prospective parallel-group study. PATIENTS AND METHODS Fifty-six adult patients scheduled to undergo orthopaedic surgery under general anaesthesia were randomly assigned to receive, either 0.9% NaCl (n=28), or HES (n=28). Cardiac preload optimization directed by oesophageal Doppler was performed after induction with fluid challenges of 250ml of solution until stroke volume (SV) no longer increased by 10%. Primary endpoint was: number of fluid challenges required to achieve SV optimization. Secondary endpoints were: number of patients responding to the first fluid challenge, proportion of patients requiring ephedrine and the ephedrine dose required to restore arterial pressure. RESULTS Percentages of responders were 61% and 63% in the 0.9% NaCl and HES groups, respectively. Number of fluid challenges necessary for SV optimization was not significantly different between 0.9% NaCl group and HES group (2 [1-2] versus 2 [1-2], P=0.33). Number of patients needing ephedrine, and well as the associated ephedrine dose, did not differ significantly. CONCLUSIONS Our study suggests that after induction, crystalloid and colloid expand the intravascular volume with equivalent efficacy immediately after administration and correct in a similar way the postinduction hypotension.

Tracheal extubation with suction vs. positive pressure during emergence from general anaesthesia in adults: a randomised controlled trial

BACKGROUND After general anaesthesia (GA) in adults, the optimal tracheal extubation technique (positive pressure or suctioning) remains debated. The primary endpoint of this study was to assess the effects of these techniques on onset time of desaturation (SpO2<92%). METHODS Sixty-nine patients with a body mass index<30 scheduled for elective orthopaedic surgery were allocated to positive pressure (PP) or suctioning (SUC) group. GA was standardised with propofol and remifentanil via target-controlled infusion. A morphine bolus of 0.15mg/kg was administered 20-30mins before the end of surgery. The effect of extubation technique on onset time of desaturation (T92) was assessed during the first 10mins after extubation during the spontaneous air breathing. Secondary endpoints included: frequency of desaturation, respiratory complications, need to use oxygen therapy and SpO2 at the end of the first hour while breathing in air (ClinicalTrials.gov identifier: NCT01323049). RESULTS Baseline patient characteristics and intraoperative management data for the 68 patients included had no relevant clinical difference between groups. T92 (sec) after tracheal extubation was 214 (168) vs. 248 (148) in the PP and SUC groups, respectively (P=0.44). In the PP and SUC groups, 50 and 43% reached a SpO2<92% within the first 10mins after extubation respectively (P=0.73). There were no statistically significant differences between groups for any secondary endpoints. CONCLUSIONS Positive pressure extubation as compared with suctioning extubation did not seem to delay onset time of desaturation after GA in standard weight adult patients.