Philippe Gautier

Intrathecal ropivacaine and clonidine for ambulatory knee arthroscopy: a dose-response study.

BackgroundThe aim of this study was to evaluate the association of a small dose of intrathecal ropivacaine with small doses of intrathecal clonidine for ambulatory surgery. MethodsOne hundred twenty patients, classified as American Society of Anesthesiologists physical status I and scheduled for knee arthroscopy, were studied. Patients were randomly assigned to receive 4 ml of one of the following double-blinded isobaric intrathecal solutions: 8 mg of ropivacaine (group 1; n =30); 8 mg ropivacaine plus 15 &mgr;g clonidine (group 2; n =30); 8 mg ropivacaine plus 45 &mgr;g clonidine (group 3; n =30); and 8 mg ropivacaine plus 75 &mgr;g clonidine (group 4; n =30). The level and duration of sensory anesthesia were recorded, along with the intensity and duration of motor block. Patient and surgeon were interviewed to evaluate the quality of anesthesia. ResultsIntrathecal ropivacaine (8 mg alone) produced short sensory anesthesia and motor blockade (132 ± 38 min and 110 ± 35 min; mean ± SD). However, the quality of anesthesia was significantly lower than in any other group (P < 0.05). Ropivacaine (8 mg) plus 75 &mgr;g clonidine produced significantly longer sensory and motor anesthesia (195 ± 40 min and 164 ± 38 min;P < 0.05). However, this was associated with systemic effects, such as sedation and reduction of arterial blood pressure. Ropivacaine (8 mg) plus 15 &mgr;g clonidine did not prolong sensory or motor blockade, afforded high quality anesthesia, and was not associated with detectable systemic effects. ConclusionSmall-dose intrathecal clonidine (15 &mgr;g) plus 8 mg intrathecal ropivacaine produces adequate and short-lasting anesthesia for knee arthroscopy.

Epidural clonidine or bupivacaine as the sole analgesic agent during and after abdominal surgery: a comparative study.

BACKGROUND The rationale of this study was to compare high-dose epidural clonidine with a more commonly used agent, such as bupivacaine. This was performed to give a more objective idea of the relative analgesic potency of epidural clonidine. METHODS Sixty patients undergoing intestinal surgery during propofol anesthesia were studied. At induction, the patients received epidurally a dose of 10 micrograms/kg [corrected] clonidine in 7 ml saline followed by an infusion of 6 micrograms [corrected] x kg(-1) x h(-1) (7 ml/h) (group 1, n = 20), a dose of 7 ml bupivacaine, 0.5%, followed by 7 ml/h bupivacaine, 0.25% (group 2, n = 20), or a dose of 7 ml bupivacaine, 0.25%, followed by 7 ml/h bupivacaine, 0.125% (group 3, n = 20). Intraoperatively, increases in arterial blood pressure or heart rate not responding to propofol (0.5 mg/kg) were treated with intravenous alfentanil (0.05 mg/kg). Additional doses of propofol were given to maintain an adequate bispectral index. The epidural infusions were maintained for 12 h. In cases of subjective visual analogue pain scores up to 5 cm at rest or up to 8 cm during coughing, the patients were given access to a patient-controlled analgesia device. RESULTS During anesthesia, patients in group 1 required less propofol than those in groups 2 and 3 (78 [36-142] mg vs. 229 [184-252] mg and 362 [295-458] mg; P < 0.05) and less alfentanil than patients in group 3 (0 [0-0] mg vs. 11 [6-20] mg; P < 0.05). Analgesia lasted 380 min (range, 180-645 min) in group 1 versus 30 min (range, 25-40 min) in group 2 and 22 min (range, 12.5-42 min) in group 3 (P < 0.05). There was no suggestion of a hemodynamic difference among the three groups except for heart rates that were significantly reduced in patients in group 1. Sedation scores were significantly higher in this group during the first 2 h postoperatively. CONCLUSION Our results show that high doses of epidural clonidine potentiate general anesthetics and provide more efficient postoperative analgesia than the two bupivacaine dosage regimens investigated.

Can ropivacaine and levobupivacaine be used as test doses during regional anesthesia

BackgroundLower systemic toxicity reported with ropivacaine and levobupivacaine may produce less reliable recognition of inadvertent intravenous injection during regional anesthesia. This study was undertaken to determine whether ropivacaine and levobupivacaine are suitable for use as intravenous test doses by evaluating central nervous system (CNS) symptoms after intravenous bolus injection. MethodsInstitutional approval and informed consent were granted for the study. One hundred twenty patients scheduled to undergo elective surgery were randomly assigned to receive 5 ml intravenous saline, 100 mg lidocaine, 25 mg ropivacaine, or 25 mg levobupivacaine before anesthesia. Patients reported CNS symptoms after injection and were monitored for hemodynamic change. ResultsIntravenous ropivacaine or levobupivacaine produced CNS symptoms in only 52% and 57% of patients, respectively, compared with 87% of patients after lidocaine (P < 0.02). Despite preparatory instruction, many patients receiving ropivacaine or levobupivacaine did not spontaneously volunteer symptoms because they were subtle and admitted symptoms only after in-depth questioning by the investigator. ConclusionsPlain ropivacaine and levobupivacaine (25 mg) solutions are unsuitable for use as intravenous test doses during regional anesthesia because CNS symptoms are insufficient. When using ropivacaine or levobupivacaine for regional anesthesia, for test dose purposes, the authors recommend the addition of epinephrine to the local anesthetic solution or the use of a separate agent with more predictable CNS characteristics.

Effective Volume of Ropivacaine 0.75% Through a Catheter Required for Interscalene Brachial Plexus Blockade

Background:Ultrasound guidance during peripheral nerve blocks has allowed for reduction in dose and volume of local anesthetic required to accomplish successful blockade using multiple injections through a needle. The authors undertook this study to determine the minimal effective volume required to accomplish successful interscalene brachial plexus block (ISB) through the catheter. Methods:After obtaining institutional ethics committee approval and written informed consent, patients aged 18–75 yr and scheduled for arthroscopic shoulder surgery under ISB were enrolled. All patients using a step-up/step-down method and the starting dose of 15 ml of 0.75% ropivacaine received an ultrasound-guided ISB catheter. The injection volume was increased or decreased by 1 ml in case of block failure or block success, respectively. Results:The authors found that the proportion of patients with successful blockade increased sharply from approximately 57% at 6 ml to 100% by 7 ml, indicating that a small increase in volume of ropivacaine 0.75% markedly affects the success rate. A total of 12 ISB with injection volume less than 7 ml resulted in successful anesthesia within 30 min, yielding an ED95 of 7 ml (95% CI 6.8–7.2) ropivacaine 0.75%. For the group as a whole, the median (min–max) sensory block onset time was 5 (5–20) min, the median (min–max) motor blocks for the biceps and the deltoid muscles were 7.5 (5–15) min and 10 (5–15) min, respectively. The median (min–max) block duration was 8.9 (3–15) h. Conclusions:An injection of a minimum of 7 ml of ropivacaine 0.75% through the catheter is required for success rate and timely onset of surgical anesthesia with ISB.

The Disposition of Radiocontrast in the Interscalene Space in Healthy Volunteers.

BACKGROUND:We measured the spread of radiocontrast in the interscalene space after injection under low (<15 psi) and high (>20 psi) pressures. METHODS:Nine healthy volunteers received ultrasound-guided injections of 10 mL radio-opaque NaCl 0.9% in both interscalene spaces. Spread of injectate as assessed by computed tomography scan and discomfort on injection were recorded. RESULTS:Under both opening pressure conditions, injectate contacted 3 brachial plexus roots and spilled over the surface of the anterior and/or middle scalene muscles underneath the cervical fascia. CONCLUSIONS:Regardless of injection pressure, the interscalene space was filled with 10 mL of radiocontrast injectate.

Principles of Major Nerve Blockade for the Perioperative Clinician: Indications, Common Side Effects, and Complications

The peripheral nerve blocks have become a commonplace in the clinical practice of anesthesiology. The perioperative physician is very likely to encounter patients who received peripheral nerve block for purpose of anesthesia or analgesia as well as their side effects or complications. In order to recognize expected neurologic and physiologic effects of nerve blockade from complications, the perioperative physician should be familiar with the principles of practice of peripheral nerve blocks and recent advances in the field. The purpose of this chapter is to highlight the essential aspects of nerve blocks, aiming primarily for practitioners whose training may not have included adequate information on this topic. We hope that this chapter and its didactic approach through numerous illustrations will be of assistance to neurologists or perioperative clinicians who encounter a patient with a side effect or neurologic complication after peripheral nerve blockade.