What Is the Minimum Effective Volume of Local Anesthetic Required for Sciatic Nerve Blockade? A Prospective, Randomized Comparison Between a Popliteal and a Subgluteal Approach (original) (raw)
Related papers
Anesthesia & Analgesia, 2008
BACKGROUND: It remains unknown whether local anesthetic concentration, or simply total drug dose, is the primary determinant of continuous peripheral nerve block effects. We therefore tested the null hypothesis that providing different concentrations and rates of ropivacaine, but at equal total doses, produces comparable effects when used in a continuous sciatic nerve block in the popliteal fossa. METHODS: Preoperatively, a perineural catheter was inserted adjacent to the sciatic nerve using a posterior popliteal approach in patients undergoing moderately painful orthopedic surgery at or distal to the ankle. Postoperatively, patients were randomly assigned to receive a perineural ropivacaine infusion of either 0.2% (basal 8 mL/h, bolus 4 mL) or 0.4% (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Therefore, both groups received 16 mg of ropivacaine each hour with a possible addition of 8 mg every 30 min via a patient-controlled bolus dose. The primary end point was the incidence of an insensate limb, considered undesirable, during the 24-h period beginning the morning after surgery. Secondary end points included analgesia and patient satisfaction. RESULTS: Patients given 0.2% ropivacaine (n ϭ 25) experienced an insensate limb with a mean (sd) of 1.8 (1.8) times, compared with 0.6 (1.1) times for subjects receiving 0.4% ropivacaine (n ϭ 25; estimated difference ϭ 1.2 episodes, 95% confidence interval, 0.3-2.0 episodes; P ϭ 0.009). In contrast, analgesia and satisfaction were similar in each group. CONCLUSIONS: For continuous popliteal-sciatic nerve blocks, local anesthetic concentration and volume influence block characteristics. Insensate limbs were far more common with larger volumes of relatively dilute ropivacaine. During continuous sciatic nerve block in the popliteal fossa, a relatively concentrated solution in smaller volume thus appears preferable.
Anesthesia & Analgesia, 2004
We studied three different injection techniques of sciatic nerve block in terms of block onset time and efficacy with 0.75% ropivacaine. A total of 75 patients undergoing foot surgery were randomly allocated to receive sciatic nerve blockade by means of the classic posterior approach (group classic; n ϭ 25), a modified subgluteus posterior approach (group subgluteus; n ϭ 25), or a lateral popliteal approach (group popliteal; n ϭ 25). All blocks were performed with the use of a nerve stimulator (stimulation frequency, 2 Hz; intensity, 2-0.5 mA) and 30 mL of 0.75% ropivacaine. Onset of nerve block was defined as complete loss of pinprick sensation in the sciatic nerve distribution with concomitant inability to perform plantar or dorsal flexion of the foot. In the three groups, an appropriate sciatic stimulation was elicited at Ͻ0.5 mA. The failure rate was similar in the three groups (group popliteal: 4% versus group classic: 4% versus group subgluteus: 8%). The onset of nerve block was slower in group popliteal (25 Ϯ 5 min) compared with group classic (16 Ϯ 4 min) and group subgluteus (17 Ϯ 4 min; P Ͻ 0.001). There was no significant difference in the onset of nerve block between group classic and group subgluteus. No differences in the degree of pain measured at the first postoperative administration of pain medication were observed among the three groups. We conclude that the three approaches resulted in clinically acceptable anesthesia in the distribution of the sciatic nerve. The subgluteus and classic posterior approaches generated a significantly faster onset of anesthesia than the lateral popliteal approach. (Anesth Analg 2004;98:242-7)
Techniques in Regional Anesthesia and Pain Management, 1999
Sciatic nerve blocks are infrequently performed by anesthesiologists. These blocks are considered to be more difficult, and they require the use of long needles, causing apprehension to both the patient and the anesthesiologist. However, the use of nerve stimulators significantly facilitates the approach of the sciatic nerve. The nerve can essentially be blocked either high or at the popliteal fossa (popliteal block) before or at its division. Although surgery of the lower extremity does not necessarily require sciatic nerve conduction to be blocked, when indicated, this is a very effective method for controlling pain and reducing the length of hospitalization, the latter leading to substantial savings. Different approaches have been described (eg, posterior, anterior and lateral). Each approach has specific indications that need to be recognized. Consequently it is necessary to be familiar with more than one approach. Thus, a parasacral or classic posterior approach of the sciatic nerve is recommended in lateral positions, whereas the anterior approach is favored in the supine patient. When the strategy of anesthesia is developed or the placement of a catheter is considered, it is important to recognize that sciatic blocks have the slowest onset and longest duration compared with all other peripheral nerve blocks performed by anesthesiologists. For single injections in adults, our preference is a combination of 1.5% lidocaine and 0.75% ropivacaine (equivolumes) with the addition of bicarbonate and epinephrine for a total volume of 20 to 30 mL in adults. Copyright 9 1999 by W.B. Saunders Company ecent efforts to reduce the length of hospital stay for inpatients and turnaround time in outpatient centers, and to improve pain control and outcome have contributed to the renewed interest in peripheral nerve blocks.l Jankowski et al. z reported that the use of 3-in-1 block for knee arthroscopy resulted in a 30% decrease in recovery room time and savings of more than $1,300. Other factors have also been involved in this "renaissance" of interest, including better training in regional anesthesia, and an increased understanding by surgeons of the risk/benefit ratio of peripheral nerve blocks. Finally, the consistent effort to minimize the risks of anesthesia and its consequences on the cardiovascular system and better education regarding anesthesia alternatives have also led to an increased demand for peripheral nerve blocks. Among the peripheral blocks performed by anesthesiologists, the sciatic nerve blocks are the least frequently per
Sciatic nerve blockade in the supine position: a novel approach
Canadian Journal of Anesthesia/Journal canadien d'anesthésie, 2003
Sciatic nerve block is useful for surgery below the knee both intra-and postoperatively. Several techniques to insert a catheter at the knee level or higher have been described but need mobilization (lateral decubitus) of the patient. We describe novel landmarks, using a high lateral approach, to block the sciatic nerve without moving the patient. C Cl li in ni ic ca al l f fe ea at tu ur re es s: : One hundred seven ASA I, II and III ASA patients scheduled for major foot or ankle surgery were studied prospectively. With patients awake and lying in the supine position, the catheter was introduced along novel landmarks in the peri-nervous adipose space using specifically designed material and nerve stimulation (< 0.5 mA). After a negative test dose (1% lidocaine with 1/200.000 epinephrine), 10 mL of 0.5% bupivacaine and 10 mL of 2% lidocaine were injected. Thirty minutes after performance of the block, the cutaneous and dermatomal sensory blockade were assessed using cold and pinprick tests while motor block was assessed using a modified Bromage scale. Complications and incidents were recorded. The tibial and superficial peroneal nerve were always blocked, while the deep peroneal and posterofemoral cutaneous nerves were blocked in only 97% and 83% of the patients, respectively. Anesthesia, was always present in the dermatome L5 and in the S1 dermatome in 98% of the patients. No major incidents or complications were noted. Three catheters could not be inserted and the anesthestic solution was injected through the needle. C Co on nc cl lu us si io on n: : The lateral technique for sciatic nerve anesthesia and catheter insertion allows patients to remain in the supine position for performance of the block and catheter insertion, and results in a high rate of homogeneous anesthesia and a low incidence of side effects.
A comparison of 0.5% ropivacaine and 1% mepivacaine for sciatic nerve block in the popliteal fossa
Acta Anaesthesiologica Scandinavica, 2001
The purpose of this study was to compare anesthetic efficacy and postoperative analgesia of 0.5% ropivacaine and 1% mepivacaine for sciatic nerve block in the popliteal fossa (popliteal block). Methods: A prospective, double-blind study was carried out in 58 adult patients scheduled for outpatient foot or ankle surgery. They were randomized to receive popliteal block with 40 ml of either 0.5% ropivacaine (group R) or 1% mepivacaine (group M). An atraumatic, Teflon-coated needle connected to a neurostimulator was used to make a single puncture using a posterior approach. The times to onset of sensory and motor block, and the need for intraoperative sedation were recorded. Before discharge, patients were asked to document the time to first analgesic use, time to return of full sensation in the foot, and their evaluation of the technique. Results: Onset time (mean∫standard deviation, 95% confidence interval) of both sensory block (6.5∫5.1 min, 4.47-8.49, in group R and 6.2∫3.7 min, 4.83-7.69, in group M) and motor block
Anesthesia & Analgesia, 2005
We prospectively tested the hypothesis that the use of a stimulating catheter improves the efficacy of continuous posterior popliteal sciatic nerve block in 100 randomized patients scheduled for elective orthopedic foot surgery. After eliciting a sciatic mediated muscular twitch at Յ0.5 mA nerve stimulation output, the perineural catheter was advanced 2-4 cm beyond the tip of the introducer either blindly (Group C; n ϭ 50) or stimulating via the catheter (Group S; n ϭ 50). A bolus dose of 25 mL of 1.5% mepivacaine was followed by a postoperative patientcontrolled infusion of 0.2% ropivacaine (basal infusion: 3 mL/h; incremental dose: 5 mL; lockout time: 30 min). Propacetamol 2 g IV was administered every 8 h, and opioid rescue analgesia was available if required. Catheter placement required 7 Ϯ 2 min in Group S and 5 Ϯ 2 min in Group C (P ϭ 0.056). A significantly shorter onset time of both sensory and motor blocks was noted in Group S. No difference in quality of pain relief at rest and during motion was reported between the groups. Median (range) local anesthetic consumption during the first 48 h after surgery was 239 mL (175-519 mL) and 322 mL (184 -508 mL) in Groups S and C, respectively (P ϭ 0.002). Rescue opioid analgesia was required by 12 (25%) and 28 (58%) patients in Groups S and C, respectively (P ϭ 0.002). We conclude that the use of a stimulating catheter results in shorter onset time of posterior popliteal sciatic nerve block, similar pain relief with reduced postoperative consumption of local anesthetic solution, and less rescue opioid consumption.
The parasacral sciatic nerve block
Regional Anesthesia and Pain Medicine, 1997
Background and Objectives. The clinical utility of a new parasacral approach for conduction block of the sciatic nerve was investigated, with critical examination of onset, extent, and success rates when this block was used for surgical procedures below the knee. Methods. Thirty ASA I-III patients presenting for surgery on the lower limb were enrolled. All received 30 mL of 1.5% lidocaine with 1:200,000 epinephrine following nerve stimulator identification of the sciatic nerve at _<0.2 mA or less. Trans-sartorial saphenous nerve blocks were performed to provide anesthesia to the medial leg. Results. Overall success for surgical anesthesia with this block was 97%. All components of the sacral plexus could be blocked with this approach, and 93% of patients displayed evidence of obturator nerve motor block. However, no patient displayed evidence of obturator sensory anesthesia that could be mapped. Saphenous nerve blocks were 100% effective in providing surgical anesthesia for the procedures performed. Conclusions: The parasacral approach to the sciatic nerve exhibits a high success rate, resulting in anesthesia of the entire sacral plexus and generally in motor block of the obturator nerve was an interesting observation.