Nathalie Vialles

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.

Spinal Anesthesia-induced Hypotension: A Risk Comparison Between Patients with Severe Preeclampsia and Healthy Women Undergoing Preterm Cesarean Delivery

We previously showed that, in comparison with term healthy parturients, patients with severe preeclampsia had a less frequent incidence of spinal hypotension, which was less severe and required less ephedrine. In the present study, we hypothesized that these findings were attributable to preeclampsia-associated factors rather than to a smaller uterine mass. The incidence and severity of hypotension were compared between severe preeclamptics (n = 65) and parturients with preterm pregnancies (n = 71), undergoing spinal anesthesia for cesarean delivery (0.5% bupivacaine, sufentanil, morphine). Hypotension was defined as the need for ephedrine (systolic blood pressure <100 mm Hg in parturients with preterm fetuses or 30% decrease in mean blood pressure in both groups). Apgar scores and umbilical arterial blood pH were also studied. Neonatal and placental weights were similar between the groups. Hypotension was less frequent in preeclamptic patients than in women with preterm pregnancies (24.6% versus 40.8%, respectively, P = 0.044). Although the magnitude of the decrease in systolic, diastolic, and mean arterial blood pressure was similar between groups, preeclamptic patients required less ephedrine than women in the preterm group to restore blood pressure to baseline levels (9.8 ± 4.6 mg versus 15.8 ± 6.2 mg, respectively, P = 0.031). The risk of hypotension in the preeclamptic group was almost 2 times less than that in the preterm group (relative risk = 0.603; 95% confidence interval, 0.362–1.003; P = 0.044). The impact of Apgar scores was minor, and umbilical arterial blood pH was not affected. We conclude that preeclampsia-associated factors, rather than a smaller uterine mass, account for the infrequent incidence of spinal hypotension in preeclamptic patients.

Single-shot intraoperative local anaesthetic infiltration does not reduce morphine consumption after total hip arthroplasty: a double-blinded placebo-controlled randomized study

BACKGROUND The infiltration of local anaesthetic (LA), ketorolac, and epinephrine has been suggested to be effective for analgesia after total hip arthroplasty (THA). The part of action of each component of the mixture remains unclear. We investigated the contribution of infiltration of ropivacaine alone on the morphine consumption during the first 24 h after surgery. METHODS Sixty patients undergoing primary THA were included in this prospective randomized double-blinded placebo-controlled trial, after IRB approval and informed consent. Surgical and general anaesthetic management were standardized. At the end of surgery, 80 ml of ropivacaine 0.2% (160 mg) or saline was infiltrated. The primary endpoint was morphine consumption 24 h after surgery. The secondary endpoints were: visual analogue scale scores and opioid side-effects at H2, H4, H8, H12, H24, D1, D2, D3, D4, D5, rehabilitation programme progress, chronic pain level, analgesic consumption, and surgical result at 3 months and 1 yr after surgery. The observation period was 1 yr. RESULTS Groups were similar for patient characteristic and perioperative characteristics. The ropivacaine wound infiltration did not reduce morphine consumption at 24 h [median (25th and 75th inter-quartile) 27 (17-37) mg in the ropivacaine group vs 24 (18-34) mg in the placebo group, P=0.51] or its side-effects. No effect was found on rehabilitation progress or chronic pain after 3 months or 1 yr, but these were not the main endpoints of the study. CONCLUSIONS Ropivacaine infiltration alone did not reduce morphine consumption at 24 h after operation nor did it improve postoperative rehabilitation.

Anesthésie et prééclampsie

An assessment of the patient must take place as early as possible in view of anaesthesia. It is recommended to perform a clotting screen as close as possible to the performing of an epidural anaesthesia. The use of aspirin, if indicated for the prevention of PE, does not as such, constitute a contraindication to performing an epidural anaesthesia if: With regards to the minimum platelet count, the recommended cut-off value for the performing of an epidural and spinal anaesthesia are 75 & 50 x 10(9)/l respectively, only if all of the following conditions are met: It is recommended to quickly set up an epidural anaesthesia because this will improve the blood pressure as well as the utero-placenteric haemodynamics and also because this will facilitate the management in case of a caesarean section. Whereas methylergometrine (Methergin) is contraindicated in the preeclamptic patient, it is possible to use oxytocin (Syntocinion) during and after labour. Before performing a spinal anaesthesia, it is recommended to restrain the administration of crystalloids to a maximum of 1000 ml. Also the i.v. antihypertensive treatment should be reduced or interrupted until complete establishment of the anaesthetic. In case a general anaesthesia is to be performed, an assessment of the criteria for difficult intubation should be performed immediately prior to the induction. The technique employed should be a rapid sequence induction with intubation, while preventing a surge in blood pressure induced by the tracheal intubation. Difficulties to extubate should systematically be anticipated. It is possible to perform a loco-regional anaesthesia following an eclamptic crisis if the following conditions are met: In case of overlapping seizures and/or impaired consciousness, a general anaesthesia is recommended.