A double-blind comparison of ropivacaine, bupivacaine, and mepivacaine during sciatic and femoral nerve blockade

CPL-01, an investigational long-acting ropivacaine, demonstrates safety and efficacy in open inguinal hernia repair

BACKGROUND

There is an unmet medical need for effective nonopioid analgesics that can decrease pain while reducing systemic opioid use. CPL-01, an extended-release injectable formulation of ropivacaine, is designed to safely provide analgesia and reduce or eliminate opioid use in the postoperative period.

METHODS

Subjects undergoing open inguinal hernia with mesh were prospectively randomized to 1 of 3 doses of CPL-01 (10, 20, or 30 ml of 2% CPL-01, n = 14, 12, and 14, respectively), Naropin (150 mg, n = 40), or saline placebo (n = 13) infiltrated into the surgical site prior to closure. Pain and rescue medication usage was assessed, and Numeric Rating Scale (NRS) pain scores were adjusted for opioid usage using windowed worst observation carried forward (wWOCF) imputation. The primary efficacy endpoint was the mean area under the curve (AUC) of the NRS pain intensity scores with activity.

RESULTS

Ninety-three subjects were treated, and 91 subjects completed 72 h of post-operative monitoring. Subjects who received the highest dose of CPL-01 in Cohort 3 showed a clinically meaningful reduction in postoperative pain intensity scores, which was the lowest value for any treatment in all cohorts, showing a trend towards statistical significance as compared to the pooled placebo group (p = 0.08), and numerically better than the 40 subjects who received Naropin. Opioid use through 72 h in subjects who received CPL-01 in Cohort 3 was approximately half of that shown in the placebo and Naropin groups; approximately 2/3 of the CPL-01 subjects (9/14) required no opioids at all through the first 72 h after the operation. More CPL-01 subjects avoided severe pain and were ready for discharge earlier than other groups. CPL-01 was safe and well-tolerated, with no clinically meaningful safety signals, and showed predictable and consistent extended-release pharmacokinetics.

CONCLUSION

Results suggest that CPL-01 may be the first long-acting ropivacaine to address postoperative pain while reducing the need for opioids.

Evaluating Pain Management from Peripheral Nerve Block for Geriatric Patients following Bipolar Hemiarthroplasty for Displaced Femoral-Neck Fracture

INTRODUCTION

The purpose of this study was to evaluate peripheral nerve block (PNB) effectiveness in postoperative pain management and surgical outcomes for displaced femoral-neck fracture in geriatric patients (>70 years) who underwent bipolar hemiarthroplasty (BHA).

METHODS

From January 2017 to December 2021, 231 geriatric patients with displaced femoral-neck fracture who consecutively underwent BHA were retrospectively reviewed. Patients were divided into two groups: the patient-controlled analgesia (PCA) group (n = 132) who received only intravenous (IV) PCA for postoperative pain management, and all others who received PNB with IV PCA (PNB+PCA) such as femoral nerve block or fascia iliaca compartment block after surgery (n = 99). Primary outcomes were postoperative visual analog scale (VAS) at rest and during activity at 6, 24, and 48 h postoperatively. Secondary outcomes were postoperative complications, changes in hemoglobin, length of hospital stay, and total morphine usage after surgery.

RESULTS

Postoperative resting VAS at 6 h and 48 h was significantly lower in the PNB+PCA group compared with the PCA group (p = 0.075, p = 0.0318, respectively). However, there was no significant difference in either resting VAS at 24 h or active VAS. Complications of pneumonia and delirium until 1 month postoperative were significantly lower in the PNB + PCA group than the PCA group (p = 0.0022, p = 0.0055, respectively).

CONCLUSION

PNB with IV PCA seems to have a beneficial effect on geriatric femoral-neck patients who underwent BHA with postoperative analgesia for reducing postoperative resting pain and complications, especially pneumonia and delirium.

Mepivacaine Versus Bupivacaine for Spinal Anesthesia: A Systematic Review and Meta-analysis of Random Controlled Trials

INTRODUCTION

Bupivacaine is a more widely used anesthetic than mepivacaine. However, the long-acting effects of bupivacaine often lead to slow and unpredictable return. As an intermediate-acting local anesthetic, mepivacaine can enable earlier ambulation and thus has other benefits. We performed a systematic review and meta-analysis of available randomized controlled trials (RCTs) comparing the anesthetic effects of mepivacaine and bupivacaine.

METHODS

On August 12, 2021, a search was performed in PubMed, Embase, and the Cochrane Library. Effect estimates with 95% CI were combined using a random effects model. We performed sensitivity analyses to explore sources of heterogeneity and stability of results.

RESULTS

Of the 406 papers screened, 14 population-based randomized controlled trials were included, with a total of 1007 patients. Overall, compared to bupivacaine, mepivacaine was associated with higher numbers of motor block 3 (OR, 4.05; 95% CI 1.92-8.57), shorter length of stay (SMD, - 0.77; 95% CI - 1.52 to - 0.03), faster recovery from motor block (SMD, - 1.45; 95% CI - 2.39 to - 0.51), and shorter time to return to voiding (SMD, - 1.24; 95% CI - 1.83 to - 0.64). Mepivacaine was associated with a higher incidence of transient neurologic symptoms (TNS) and transient nerve root irritation (TRI) (OR, 9.18; 95% CI 2.42-34.88). There was no statistical difference between the two anesthetics in terms of pain index on the postoperative day (SMD, 0.20; 95% CI - 0.06 to 0.46) and incidence of urinary retention (OR, 0.98; 95% CI 0.47-2.03).

CONCLUSIONS

Mepivacaine may have advantages over bupivacaine in terms of achieving motor block 3, shorter length of stay, earlier recovery from motor block, and earlier time to return to voiding, but it may have a higher incidence of TNS or TRI than bupivacaine. Therefore, mepivacaine may be used before bupivacaine in spinal anesthesia.

Is a Block of the Femoral and Sciatic Nerves an Alternative to Epidural Analgesia in Sheep Undergoing Orthopaedic Hind Limb Surgery? A Prospective, Randomized, Double Blinded Experimental Trial

Peripheral nerve blocks are commonly used in human and veterinary medicine. The aim of the study was to compare the analgesic efficacy of a combined block of the femoral and sciatic nerves with an epidural injection of ropivacaine in experimental sheep undergoing orthopaedic hind limb surgery. Twenty-five sheep were assigned to two groups (peripheral nerve block; sciatic and femoral nerves (P); epidural analgesia (E)). In group P 10 mL ropivacaine 0.5% was injected around the sciatic and the femoral nerves under sonographic guidance and 10 mL NaCl 0.9% into the epidural space while in group E 10 mL ropivacaine 0.5% was injected into the epidural space and 10 mL NaCl 0.9% to the sciatic and the femoral nerves. During surgery, heart rate, respiratory rate and mean blood pressure were used as indicators of nociception. In the postoperative phase, nociception was evaluated every hour by use of a purposefully adapted pain score until the animal showed painful sensation at the surgical site. The mean duration of analgesia at the surgical wound was 6 h in group P and 8 h in group E. Mean time to standing was 4 h in group P and 7 h in group E. In conclusion time to standing was significantly shorter in group P while the duration of nociception was comparable in both groups. The peripheral nerve block can be used as an alternative to epidural analgesia in experimental sheep.

Lower extremity regional anesthesia: essentials of our current understanding

The advent of ultrasound guidance has led to a renewed interest in regional anesthesia of the lower limb. In keeping with the American Society of Regional Anesthesia and Pain Medicine's ongoing commitment to provide intensive evidence-based education, this article presents a complete update of the 2005 comprehensive review on lower extremity peripheral nerve blocks. The current review article strives to (1) summarize the pertinent anatomy of the lumbar and sacral plexuses, (2) discuss the optimal approaches and techniques for lower limb regional anesthesia, (3) present evidence to guide the selection of pharmacological agents and adjuvants, (4) describe potential complications associated with lower extremity nerve blocks, and (5) identify informational gaps pertaining to outcomes, which warrant further investigation.

Human carbonic anhydrase-8 AAV8 gene therapy inhibits nerve growth factor signaling producing prolonged analgesia and anti-hyperalgesia in mice

Carbonic anhydrase-8 (Car8; murine gene symbol) is an allosteric inhibitor of inositol trisphosphate receptor-1 (ITPR1), which regulates neuronal intracellular calcium release. We previously reported that wildtype Car8 overexpression corrects the baseline allodynia and hyperalgesia associated with calcium dysregulation in the waddle (wdl) mouse due to a 19 bp deletion in exon 8 of the Car8 gene. In this report, we provide preliminary evidence that overexpression of the human wildtype ortholog of Car8 (CA8^WT), but not the reported CA8 S100P loss-of-function mutation (CA8^MT); inhibits nerve growth factor (NGF)-induced phosphorylation of ITPR1, TrkA (NGF high affinity receptor); and ITPR1-mediated cytoplasmic free calcium release in vitro. Additionally, we show that gene-transfer using AAV8-V5-CA8^WT viral particles via sciatic nerve injection demonstrates retrograde transport to dorsal root ganglia (DRG) producing prolonged V5-CA8^WT expression, pITPR1 and pTrkA inhibition, and profound analgesia and anti-hyperalgesia in male C57BL/6J mice. AAV8-V5-CA8^WT mediated overexpression prevented and treated allodynia and hyperalgesia associated with chronic neuropathic pain produced by the spinal nerve ligation (SNL) model. These AAV8-V5-CA8 data provide a proof-of-concept for precision medicine through targeted gene therapy of NGF-responsive somatosensory neurons as a long-acting local analgesic able to prevent and treat chronic neuropathic pain through regulating TrkA signaling, ITPR1 activation, and intracellular free calcium release by ITPR1.

Lower limb surgeries under combined femoral and sciatic nerve block

Introduction:

Peripheral nerve blocks are gaining popularity for many infraumblical surgeries with the development of new techniques such as ultrasound and peripheral nerve stimulator. It provides stable hemodynamic, better, and prolonged postoperative analgesia. This study was carried out to see the effectiveness of combined femoral and sciatic nerve block with ropivacaine alone and by adding fentanyl.

Materials and Methods:

The study was carried out on 100 patients scheduled for lower limb surgeries and were randomly divided into two groups of 50 each. In Group A, patients received 20 ml of 0.5% ropivacaine for femoral nerve block and same dose for sciatic nerve block and in Group B, 25 μg fentanyl was added each for femoral nerve and sciatic nerve block along with ropivacaine. All hemodynamic parameters, onset and duration of sensory and motor blocks were noted. The patient characteristics were analyzed using the “Chi-square tests” and the intergroup comparison of the parametric data was carried out using the unpaired t-test using software IBM SPSS 17.0.

Results:

Combined femoral and sciatic nerve block provide longer duration of postoperative analgesia of about 12–13 h. All the above-mentioned parameters were statistically non-significant.

Conclusion:

Hence in this study, onset and duration of sensory and motor block was comparable in both groups. However postoperative analgesia was prolonged as compared to neuraxial blockade without any hemodynamic instability.

Lower extremity bypass with tumescent local anesthesia

Lower extremity bypass is most commonly performed for the treatment of critical limb ischemia. These patients often pose high surgical risk secondary to significant clinical comorbidities. These risks may be compounded when general anesthesia is considered. We present the case of a patient at high anesthesia risk with critical limb ischemia who was unable to receive general anesthesia or neuraxial blockade. An infrainguinal bypass was performed using tumescent anesthesia with minimal intravenous sedation. The patient was discharged 6 days later, and his postoperative course was complicated by a groin lymphocele. Tumescent local anesthesia is a possible alternative pain management strategy for patients undergoing lower extremity bypass surgery.

A double-blind randomized controlled trial comparing dexamethasone and clonidine as adjuvants to a ropivacaine sciatic popliteal block for foot surgery

Background and aims

A popliteal block is effective in managing postoperative pain for foot surgery, but since the duration of analgesia is limited following a single-shot popliteal fossa block technique, methods to prolong effective postoperative analgesia are mandatory. The aim of this study was to assess the effect of adjuvants to ropivacaine on the duration of sensory and motor block.

Methods

In this double-blind randomized placebo-controlled study, we evaluated the analgesic effect of clonidine or dexamethasone (DXM) when added to ropivacaine for hallux valgus surgery. After obtaining institutional ethics research board approval and written informed consent, a total of 72 patients were randomly allocated. Fifty-seven of these patients were statistically analyzed. All patients received an ultrasound-guided single-shot popliteal fossa block with 30 mL of ropivacaine 0.75%, supplemented with saline, clonidine 100 µg, or DXM 5 mg. The primary end point was time to first pain sensation. Secondary end points were time to complete sensory and motor block regression.

Results

Compared to saline, duration to first pain sensation was prolonged by 9 hours (mean ± standard deviation: 31±9 hours) (42%) in the DXM group (P=0.024) and by 6 hours (28±10 hours) (27%) in the clonidine group (P=0.024). Compared to saline, DXM prolonged both complete sensory and motor blockade by 12 hours (25±7 hours) (46%) and 13 hours (36±6 hours) (55%), respectively, while clonidine prolonged complete sensory and motor blockade by 7 hours (30±7 hours) (27%) and 2 hours (22±5 hours) (10%), respectively. DXM prolonged sensory block regression time by 6 hours (21±7 hours) (41%) and clonidine by 2 hours (17±6 hours) (13%) compared to the control group (P=0.006). Similarly, DXM prolonged motor block regression by 7 hours (25±7 hours) (46%) and clonidine by 4 hours (21±4 hours) (19%) (P<0.0001).

Conclusion

Addition of DXM and clonidine to ropivacaine significantly prolonged the duration of postoperative sensory and motor block.

Comparison of the effects of intra-articular sole ropivacaine and combined ketorolac and ropivacaine for pain control after knee arthroscopy surgery

INTRODUCTION

Effective pain relief is important after arthroscopic knee surgery to permit initiation of daily activities of life. This study is performed in order to investigate the effect of multi-model therapy for pain control after surgery. This clinical, randomized and double-blind trial is conducted on patients who get knee arthroscopy surgery.

METHODS

Of these patients, 40 were divided into two groups by Block Randomization method: 1 - sole ropivacaine group (150 mg); 2 - combined ketorolac (30 mg); and ropivacain (150 mg) group. These drugs were injected intra-articularly at the end of knee arthroscopic surgery. The first consequence including measurement of pain severity after entrance to recovery room and 2, 4, 8, 12, 18 and 24 hours after surgery were evaluated according to the visual analogue pain score. The second consequence, including nausea, vomiting and sedation, was assessed by expert nurses in the recovery room and surgery part according to nausea and vomiting scale and Ramsay sedation scale, respectively.

RESULTS

All groups had excellent analgesia at 0 and 4 hours, postoperatively. Group-combined ketorolac and ropivacaine had significantly lower visual analogue pain score as well as higher sedative scale at 8, 12, 18 and 24 hours after surgery at rest and during movement compared with the other group (p < 0.05). Moreover, there was no statistical difference between groups in regard of nausea and vomiting.

CONCLUSION

Addition of ketolorac to ropivacaine intra-articularly in arthroscopic knee surgery enhances analgesic efficacy of local anaesthetics and cause more sedation after surgery.

Bupivacaine mandibular nerve block affects intraoperative blood pressure and heart rate in a Yucatan miniature swine mandibular condylectomy model: a pilot study

PURPOSE/AIM

The primary objective was to evaluate the effect of a bupivacaine mandibular nerve block on intraoperative blood pressure (BP) and heart rate (HR) in response to surgical stimulation and the need for systemic analgesics postoperatively. We hypothesized that a mandibular nerve block would decrease the need for systemic analgesics both intraoperatively and postoperatively.

MATERIALS AND METHODS

Fourteen adult male Yucatan pigs were purchased. Pigs were chemically restrained with ketamine, midazolam, and dexmedetomidine and anesthesia was maintained with isoflurane inhalant anesthesia. Pigs were randomized to receive a mandibular block with either bupivacaine (bupivacaine group) or saline (control group). A nerve stimulator was used for administration of the block with observation of masseter muscle twitch to indicate the injection site. Invasive BP and HR were measured with the aid of an arterial catheter in eight pigs. A rescue analgesic protocol consisting of fentanyl and lidocaine was administered if HR or BP values increased 20% from baseline. Postoperative pain was quantified with a customized ethogram. HR and BP were evaluated at base line, pre-rescue, 10 and 20 min post-rescue.

RESULTS

Pre-rescue mean BP was significantly increased (p = .001) for the bupivacaine group. Mean intraoperative HR was significantly lower (p = .044) in the bupivacaine versus saline group. All other parameters were not significant.

CONCLUSION

Addition of a mandibular nerve block to the anesthetic regimen in the miniature pig condylectomy model may improve variations in intraoperative BP and HR. This study establishes the foundation for future studies with larger animal numbers to confirm these preliminary findings.

A comparison of the onset time of complete blockade of the sciatic nerve in the application of ropivacaine and its equal volumes mixture with lidocaine: a double-blind randomized study

BACKGROUND

The purpose of the current study is to create a new mixture of local anesthetics-one with a short time of block development and short action term (5 ml of 1% lidocaine solution) and another with a longer time of anesthesia development and a long analgetic effect (5 ml of 0.75% ropivacaine)-for use during surgical operations on extremities. The primary end point was the development of the complete sensory block of the sciatic nerve.

METHODS

Sixty blocks of sciatic nerve were used in a double-blind randomized research, under ultrasonic guidance, using an electric stimulator with the peripheral nerves. Sixty patients were divided into 3 equal groups. In the first group, a sciatic nerve block was performed with 5 ml of 0.75% ropivacaine solution (37.5 mg); in the second group, 10 ml of 0.75% ropivacaine solution (75 mg) was used and, in the third group, a mixture of 5 ml of 0.75% ropivacaine (as above) and 5 ml of 1% lidocaine solution (50 mg) was used. The assessment of the time required for developing sensory and motor blocks was carried out from the beginning of local anesthetic solution injection in the fascial sheath of the sciatic nerve.

RESULTS

Demographic data of patients were identical in the three sample groups. The time required for achieving a complete motor and sensory block was reduced due to the mix of the 1% lidocaine solution with the 0.75% ropivacaine solution. The time required for achieving a complete sensory block in groups treated with 5 and 10 ml ropivacaine was 45 (40-48) and 30 (28-30) min, respectively, in contrast with 12 (10-13) min when the mixture of anesthetics was applied (P < 0.01). There was no difference in analgesic duration in the postoperative period among groups at P > 0.05.

CONCLUSIONS

The mixture of 5 ml of 1% lidocaine with 5 ml of 0.75% ropivacaine leads to a reduction in the time required for the development of complete sensory and motor blocks of the sciatic nerve, without reducing postoperative analgesia time.

Comparative evaluation of ropivacaine and lignocaine with ropivacaine, lignocaine and clonidine combination during peribulbar anaesthesia for phacoemulsification cataract surgery

Background:

Peribulbar block is the most common type of local anaesthesia administered for cataract surgery, and continuous efforts are on to find a long-acting local anaesthetic (LA) drug with the safest pharmacological profile.

Objectives:

A double-blind, prospective and randomized study was carried out in our institute to compare the anaesthetic effects of ropivacaine with the combination of ropivacaine and clonidine in administration of peribulbar block for phacoemulsification cataract surgery.

Methods:

A total of 200 patients of both sexes aged 50–80 years of American Society of Anaesthesiologists grade I and II, scheduled for phacoemulsification cataract surgery under monitored anaesthesia care, were enrolled for the study. Patients were assigned into two groups of 100 each; ropivacaine group (R) and ropivacaine clonidine group (RC). Group R received 10 mL of LA solution containing 5 mL of 2% lignocaine, 5 mL of 0.75% ropivacaine and 100 units of hyaluronidase while group RC received 8 mL of a similar mixture with the addition of clonidine 1 μg/kg and saline to make a total volume of 10 mL. Heart rate (HR), mean arterial pressure (MAP), pulse oximetry (SpO₂), respiratory rate (RR), intraocular pressure (IOP), eye muscle movement scores and quality of peribulbar block were observed and recorded throughout the study period at regular intervals. At the end of the research project, the data was compiled systematically and was subjected to statistical analysis using the ANOVA test with post hoc significance for continuous variables and Chi-square test for qualitative data. Value of P<0.05 was considered significant and P<0.0001 as highly significant.

Results:

Demographic characteristics, SpO₂ and RR were comparable in both the groups. Mean HR and MAP were also comparable after a significant variation in the first 2–3 min (P<0.05). Onset and establishment of sensory and motor blocks were significantly earlier in the RC group (P<0.05). IOP decreased significantly during the first 6–7 min in the RC group after the administration of the peribulbar block. Duration of analgesia was prolonged in the RC group (6.5±2.1 h) as compared with the R group (4.2±1.8 h). The side-effect profile revealed a higher incidence of nausea, vomiting, headache and dizziness in Group R, while a considerably higher incidence of dry mouth was observed in Group RC.

Conclusions:

Addition of clonidine to ropivacaine not only decreases the total volume of LA to be used but also augments early onset and prolonged offset of sensory analgesia as well as provides smooth operating conditions with a good sedation level as well by providing a wider safety margin of LA.

Tetrodotoxin-bupivacaine-epinephrine combinations for prolonged local anesthesia

Currently available local anesthetics have analgesic durations in humans generally less than 12 hours. Prolonged-duration local anesthetics will be useful for postoperative analgesia. Previous studies showed that in rats, combinations of tetrodotoxin (TTX) with bupivacaine had supra-additive effects on sciatic block durations. In those studies, epinephrine combined with TTX prolonged blocks more than 10-fold, while reducing systemic toxicity. TTX, formulated as Tectin, is in phase III clinical trials as an injectable systemic analgesic for chronic cancer pain. Here, we examine dose-duration relationships and sciatic nerve histology following local nerve blocks with combinations of Tectin with bupivacaine 0.25% (2.5 mg/mL) solutions, with or without epinephrine 5 µg/mL (1:200,000) in rats. Percutaneous sciatic blockade was performed in Sprague-Dawley rats, and intensity and duration of sensory blockade was tested blindly with different Tectin-bupivacaine-epinephrine combinations. Between-group comparisons were analyzed using ANOVA and post-hoc Sidak tests. Nerves were examined blindly for signs of injury. Blocks containing bupivacaine 0.25% with Tectin 10 µM and epinephrine 5 µg/mL were prolonged by roughly 3-fold compared to blocks with bupivacaine 0.25% plain (P < 0.001) or bupivacaine 0.25% with epinephrine 5 µg/mL (P < 0.001). Nerve histology was benign for all groups. Combinations of Tectin in bupivacaine 0.25% with epinephrine 5 µg/mL appear promising for prolonged duration of local anesthesia.

Ropivacaine: A review of its pharmacology and clinical use

Ropivacaine is a long-acting amide local anaesthetic agent and first produced as a pure enantiomer. It produces effects similar to other local anaesthetics via reversible inhibition of sodium ion influx in nerve fibres. Ropivacaine is less lipophilic than bupivacaine and is less likely to penetrate large myelinated motor fibres, resulting in a relatively reduced motor blockade. Thus, ropivacaine has a greater degree of motor sensory differentiation, which could be useful when motor blockade is undesirable. The reduced lipophilicity is also associated with decreased potential for central nervous system toxicity and cardiotoxicity. The drug displays linear and dose proportional pharmacokinetics (up to 80 mg administered intravenously). It is metabolised extensively in the liver and excreted in urine. The present article details the clinical applications of ropivacaine and its current place as a local anaesthetic in the group.

Ropivacaine: a review of its use in regional anaesthesia and acute pain management

Ropivacaine (Naropin) is the pure S(-)-enantiomer of propivacaine, and is a long-acting amide local anaesthetic agent, eliciting nerve block via reversible inhibition of sodium ion influx in nerve fibres. Ropivacaine is a well tolerated regional anaesthetic effective for surgical anaesthesia as well as the relief of postoperative and labour pain. The efficacy of ropivacaine is similar to that of bupivacaine and levobupivacaine for peripheral nerve blocks and, although it may be slightly less potent than bupivacaine when administered epidurally or intrathecally, equi-effective doses have been established. Clinically adequate doses of ropivacaine appear to be associated with a lower incidence or grade of motor block than bupivacaine. Thus ropivacaine, with its efficacy, lower propensity for motor block and reduced potential for CNS toxicity and cardiotoxicity, appears to be an important option for regional anaesthesia and for the management of postoperative and labour pain.

Evaluation of femoral nerve blockade following inguinal paravascular block of Winnie: are there still lessons to be learnt?

Lower limb peripheral nerve blocks are used to provide surgical anaesthesia or postoperative analgesia. Anatomical texts imply that femoral and saphenous nerve blocks be evaluated by sensory testing of the skin overlying the anterior aspect of the thigh, and the medial aspect of the foot, respectively. We have mapped the distribution of anaesthesia in 25 adults following femoral nerve blockade, performed using the inguinal paravascular technique of Winnie. There was substantial interindividual variation in the area of anaesthesia. Only the skin overlying the middle third of the medial thigh was consistently blocked in 100% of patients. The distribution of anaesthesia conformed to anatomical text descriptions in 24% of cases. We conclude that demonstration of complete quadriceps paralysis confirms femoral nerve blockade. Failing that, sensory evaluation of a femoral nerve block should involve testing the skin of the middle third of the medial aspect of the thigh. The skin overlying the anteromedial aspect of the middle third of the leg should be evaluated for saphenous nerve block.

Continuous lateral popliteal block with stimulating catheters

Foot surgery often induces severe postoperative pain. Sciatic nerve block is a good alternative for its treatment. We report two cases of continuous lateral popliteal sciatic nerve block using two different stimulating catheters. The lateral approach may offer some advantages. Stimulating catheters may be useful to verify correct catheter tip positioning. This technique seem to be easy to use and provided excellent pain relief.

Total knee replacement: a comparison of ropivacaine and bupivacaine in combined femoral and sciatic block

BACKGROUND

Femoral and sciatic nerve block may improve post-operative analgesia following total knee replacement.

OBJECTIVES

To compare the post-operative analgesia following primary total knee replacement provided by spinal anaesthesia alone or in combination with femoral and sciatic nerve block with bupivacaine or ropivacaine.

METHODS

Seventy-five patients were randomised into one of three groups: spinal anaesthesia only; spinal anaesthesia and combined femoral and sciatic nerve block with 1 mg x kg(-1) bupivacaine 7.5 mg x ml(-1) to each nerve; spinal anaesthesia and combined femoral and sciatic nerve block with 1 mg x kg(-1) ropivacaine 7.5 mg x ml(-1) to each nerve.

RESULTS

The mean (SD) time to first morphine request was significantly prolonged for both groups receiving combined femoral and sciatic block, 912 (489) min for the bupivacaine group and 781 (394) min for the ropivacaine group (P<0.001) compared with 413 (208) min for the group receiving spinal anaesthesia alone. Morphine consumption was significantly reduced in both groups receiving combined femoral and sciatic block. There were no systemic or neurological sequelae in any of the groups.

CONCLUSIONS

Femoral and sciatic blockade following intrathecal bupivacaine/diamorphine provided superior analgesia when compared with intrathecal bupivacaine/diamorphine alone. There were no significant clinical differences between the group receiving bupivacaine 7.5 mg x ml(-1) and the group receiving ropivacaine 7.5 mg x ml(-1).

Ropivacaine: an update of its use in regional anaesthesia

Ropivacaine is a long-acting, enantiomerically pure (S-enantiomer) amide local anaesthetic with a high pKa and low lipid solubility which blocks nerve fibres involved in pain transmission (Adelta and C fibres) to a greater degree than those controlling motor function (Abeta fibres). The drug was less cardiotoxic than equal concentrations of racemic bupivacaine but more so than lidocaine (lignocaine) in vitro and had a significantly higher threshold for CNS toxicity than racemic bupivacaine in healthy volunteers (mean maximum tolerated unbound arterial plasma concentrations were 0.56 and 0.3 mg/L, respectively). Extensive clinical data have shown that epidural ropivacaine 0.2% is effective for the initiation and maintenance of labour analgesia, and provides pain relief after abdominal or orthopaedic surgery especially when given in conjunction with opioids (coadministration with opioids may also allow for lower concentrations of ropivacaine to be used). The drug had efficacy generally similar to that of the same dose of bupivacaine with regard to pain relief but caused less motor blockade at low concentrations. Lumbar epidural administration of 20 to 30ml ropivacaine 0.5% provided anaesthesia of a similar quality to that achieved with bupivacaine 0.5% in women undergoing caesarean section, but the duration of motor blockade was shorter with ropivacaine. For lumbar epidural anaesthesia for lower limb or genitourinary surgery, comparative data suggest that higher concentrations of ropivacaine (0.75 or 1.0%) may be needed to provide the same sensory and motor blockade as bupivacaine 0.5 and 0.75%. In patients about to undergo upper limb surgery, 30 to 40ml ropivacaine 0.5% produced brachial plexus anaesthesia broadly similar to that achieved with equivalent volumes of bupivacaine 0.5%, although the time to onset of sensory block tended to be faster and the duration of motor block shorter with ropivacaine. Ropivacaine had an adverse event profile similar to that of bupivacaine in clinical trials. Several cases of CNS toxicity have been reported after inadvertent intravascular administration of ropivacaine, but only 1 case of cardiovascular toxicity has been reported to date. The outcome of these inadvertent intravascular administrations was favourable.

CONCLUSION

Ropivacaine is a well tolerated regional anaesthetic with an efficacy broadly similar to that of bupivacaine. However, it may be a preferred option because of its reduced CNS and cardiotoxic potential and its lower propensity for motor block.