Transient neurologic symptoms after spinal anesthesia with mepivacaine and lidocaine

The effect of needle type (25 G Sprotte vs. Quincke) in spinal anesthesia on the incidence of transient neurologic syndrome: A randomized clinical trial

Background and Aims

Transient neurologic syndrome (TNS) is a postoperative pain in the back and buttock that can occur after spinal anesthesia. The spinal needle design may have an impact on the occurrence of TNS. We decided to compare the incidence of TNS and related factors between two spinal needle types.

Methods

In this randomized clinical trial, 150 patients aged 18-60 years and American Society of Anesthesiologists (ASA) physical status I who underwent lower abdomen or lower extremity surgeries with spinal anesthesia and supine position were enrolled. They were randomly divided into two groups (25 G Quincke or Sprotte needle) with 0.5% bupivacaine (12.5 mg). After the operation, the patients were asked to report any pain in the lower back, buttock, and thigh areas. A Visual Analog Scale (VAS) was also used to record the severity of the pain.

Results

Overall, 45 patients developed TNS. Twenty-nine patients in the Sprotte group (38.7%) and 16 patients in the Quincke group (21.3%) developed TNS (p = 0.75). More patients in the Sprotte group (25.3%) had severe pain (VAS score of 8-10) when compared with the Quincke group (6.7%). There was no significant difference in TNS symptoms duration between the two groups. In about half of patients (51.9%) in the Sprotte group and 57.3% of patients in the Quincke group, the symptoms resolved after 2-3 h.

Conclusion

Although the incidence of TNS did not differ significantly, patients for whom a Sprotte spinal needle had been used had more severe pain. This suggests that the Quincke needle caused less severe pain.

The Safety of Peripheral Nerve Blocks: The Role of Triple Monitoring in Regional Anaesthesia, a Comprehensive Review

Regional anaesthesia, referred to as regional blocks, is one of the most frequently used methods of anaesthesia for surgery and for pain management. Local anaesthetic drug should be administered as close to the nerve as possible. If administered too far away, this may result in insufficient block. If it is administrated too close, severe nerve damage can occur. Neurostimulation techniques and ultrasound imaging have improved the effectiveness and safety of blockade, but the risk of nerve injury with permanent nerve disfunction has not been eliminated. Intraneural administration of a local anaesthetic damages the nerve mechanically by the needle and the high pressure generated by the drug inside the nerve. In many studies, injection pressure is described as significantly higher for unintended intraneural injections than for perineural ones. In recent years, the concept of combining techniques (neurostimulation + USG imaging + injection pressure monitoring) has emerged as a method increasing safety and efficiency in regional anaesthesia. This study focuses on the contribution of nerve identification methods to improve the safety of peripheral nerve blocks by reducing the risk of neural damage.

Major complications of caudal block: A prospective survey of 973 cases in adult anorectal surgery

Background

We conducted a prospective study of surgical inpatients at a teaching hospital to assess the incidence and potential risk factors for major complications of caudal anesthesia in anorectal surgery.

Methods

A total of 973 patients undergoing anorectal surgery under caudal block were included in this prospective, observer-blinded trial after providing consent. Demographic information, detailed perioperative information, anesthesia-related complications and postoperative follow-up information were recorded. Meanwhile, the incidence and risk factors for major caudal anesthesia-related complications were analyzed.

Results

A total of 973 patients underwent caudal block. The effective rate was 95.38 % (928 cases). However, there were still 38 (3.91 %) cases with insufficient block and 7 (0.72 %) cases with no block. The major anesthesia-related complications were local anesthetic systemic toxicity (9, 0.92 %), cauda equine syndrome (1, 0.10 %), transient neurological symptoms (3, 0.31 %) and localized pain at the caudal insertion site (30, 3.08 %). The identified risk factor for local anesthetic systemic toxicity was multiple attempts locating the caudal space (OR = 5.30; 1.21-23.29). The identified risk factor for localized pain at the caudal insertion site was multiple attempts locating the caudal space (OR = 10.57; 4.89-22.86).

Conclusion

The main complications of caudal block in adult patients are transient neurological symptoms, cauda equine syndrome, serious local anesthetic systemic toxicity and localized pain at the caudal insertion site. Overall, the incidence of complications is low and symptoms are mild. Caudal block is still a safe and reliable method for anesthesia in adult anorectal surgery.

Postpartum complications following neuraxial anaesthesia for obstetric physicians

Neuraxial analgesia and anaesthesia are widely accepted and well-tolerated modes of delivery analgesia, being employed in up to 76% of vaginal deliveries and 94% of caesarean deliveries in the United States.1 A cause of considerable concern for postpartum women, their family and caring health professionals is the occurrence of unexplained postpartum complications, not only for management in the index pregnancy, but the uncertain risk of recurrence in future pregnancies. Complications of neuraxial blocks may impact significantly on the ability of mothers to care for and bond with their newborn. The reported incidence of temporary neurological deficit following obstetric neuraxial blocks is 1 in 3900 procedures, and the risk of permanent neurological harm estimated to be between 1 in 80,000 and 1 in 320,425 procedures.2 Obstetric physicians may be asked to review women with postpartum complications following neuraxial blocks. This article reviews complications that may be seen following neuraxial blocks for delivery.

Paresthesia in dentistry: The ignored neurotoxicity of local anesthetics

Local anesthetics are frequently used by dentists to relieve localized discomfort of the patient and improve treatment conditions. The risk of paresthesia after local anesthesia is frequently encountered in dental clinics. The neurotoxicity of local anesthetics is a disregarded factor in paresthesia. The review summarizes the types of common local anesthetics, incidence and influencing factors of paresthesia after local anesthesia, and systematically describes the neurotoxicity mechanisms of dental local anesthetic. Innovative strategies may be developed to lessen the neurotoxicity and prevent paresthesia following local anesthesia with the support of a substantial understanding of paresthesia and neurotoxicity.

Intrathecal 1% 2-chlorprocaine for short gynecological day care procedures: Prospective, randomized, dose finding study

Background and Aims

Establishing the optimum dose of intrathecal 1% 2-chlorprocaine may reduce the discharge time and encourage more widespread use of spinal anesthesia for day care procedures. The aim of this study was to compare the efficacy and recovery characteristics of three different doses of intrathecal 1% 2-chlorprocaine for short gynecological day care procedures.

Material and Methods

Fifty-one patients scheduled for elective day care gynecological procedures lasting less than 60 min and were randomly divided into three groups of 17 each to receive 35 mg, 40 mg, or 45 mg intrathecal 1% 2-chlorprocaine. Demographic data, time required to achieve readiness for surgery, time required to attain discharge criteria, maximum block height achieved, and adverse effects were recorded in each group.

Results

The time required to achieve readiness for surgery was similar between the three groups (P = 0.306). However, 35 mg group required the shortest time to ambulate and there was a significant difference as compared with both 40 mg (P = 0.012) and 45 mg (P = 0.001). Voiding and the fulfillment of the discharge parameters were also attained more rapidly in the 35 mg group [133 (120,155) min] as compared with both 40 mg [164 (145,175) min, P = 0.000] and 45 mg [160 (150,175) min, P = 0.000]. None of the patients reported neurological symptoms during the follow-up.

Conclusion

The 35 mg intrathecal 1% 2-chlorprocaine not only provides reliable anesthesia for short gynecological procedures but also facilitates faster achievement of the discharge parameters as compared with the 40 mg and 45 mg doses.

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.

Lower Dosing of Bupivacaine Spinal Anesthesia Is Not Associated With Improved Perioperative Outcomes After Total Joint Arthroplasty

Background

The choice of anesthesia plays a significant role in the success of total joint arthroplasty (TJA). Isobaric bupivacaine spinal anesthesia is often used. However, dosing of bupivacaine has not been extensively studied and is usually at the discretion of the treating anesthesiologist and surgeon. The goal of this study was to determine what, if any, effect the dose of bupivacaine spinal anesthesia had on perioperative outcomes in TJA.

Methods

A total of 761 TJAs performed with bupivacaine spinal anesthesia by arthroplasty surgeons were retrospectively reviewed. Perioperative outcomes evaluated were operation duration, estimated blood loss, length of stay (LOS) in the postanesthesia care unit, hospital LOS, discharge disposition, episodes of intraoperative hypotension, postoperative nausea and vomiting, and missed physical therapy sessions because of postoperative symptoms of hypotension. A Student’s t-test was used for continuous variables, and a chi-squared test was used for categorical variables.

Results

Of the 761 patients, 499 (65.6%) received 15 mg isobaric bupivacaine while 262 (34.4%) received <15 mg (range = 7.5-14.5 mg, median = 12.5 mg). With the numbers available in this cohort, lower doses of bupivacaine were not associated with any significant differences between groups for any of the studied perioperative outcomes, including proportion of patients discharged home or LOS.

Conclusion

Dosage of bupivacaine spinal anesthetic did not affect perioperative outcomes. Bupivacaine may not have a dose-related response curve in this regard, and if seeking to perform same-day or outpatient TJA, other agents may need to be considered, rather than smaller doses of bupivacaine.

Spinal arachnoid sleeves and their possible causative role in cauda equina syndrome and transient radicular irritation syndrome

INTRODUCTION

We have previously described arachnoid sleeves around cauda equina nerve roots, but at that time we did not determine whether injections could be performed within those sleeves. The purpose of this observational study was to establish whether the entire distal orifice of a spinal needle can be accommodated within an arachnoid sleeve.

MATERIALS AND METHODS

We carefully dissected the entire dural sacs off four fresh cadavers, opened them by longitudinal incision, and immersed them in saline. Under direct vision, we penetrated the cauda equina roots nerves traveling almost vertically downward at 30 locations each with a 27- and a 25-G pencil-point needle (60 punctures total). We captured the images with a stereoscopic camera.

RESULTS

The nerve root offered no noticeable resistance to needle entry. Although the arachnoid sleeves could not be identified with the naked eye, they were translucent but visible under microscopy. In 21 of 30 attempts with a 27-gauge needle, and in 20 of 30 attempts with a 25-gauge needle, the distal orifice of the spinal needle was completely within the arachnoid sleeve.

CONCLUSION

It seems possible to accommodate the distal orifice of a 25- or a 27-gauge pencil-point spinal needle completely within the space of the arachnoid sleeve. An injection within this sleeve could potentially lead to a neurological syndrome, as we have previously proposed.

Distinguishing cerebrospinal fluid from mepivacaine using the pH test in patients undergoing elective cesarean section with combined spinal-epidural anesthesia

INTRODUCTION

In single-space combined spinal-epidural anesthesia (CSEA), it is important to correctly determine if the fluid coming out of the spinal needle is cerebrospinal fluid (CSF) or the liquid used in the loss of resistance (LOR) technique. In this study, we used mepivacaine for LOR and measured the pH values of CSF and mepivacaine to determine whether the pH test is a reliable method to confirm CSF when performing single-space CSEA.

METHODS

This clinical trial included 47 full-term pregnant women who underwent cesarean section. Single-space CSEA was administered at the lumbar intervertebral space using a small amount of mepivacaine for LOR. The pH values of CSF and mepivacaine were determined by the color of the test strip immediately after dropping. The area under the curve (AUC) for the pH values was calculated to determine the cutoff value for distinguishing between CSF and mepivacaine.

RESULTS

The median pH values were 7.7 (7.1-8.0) and 6.2 (5.9-6.8) for CSF and mepivacaine, respectively. When the cutoff value of pH for distinguishing CSF from mepivacaine was 7.1 or greater, the AUC was 1.0 (100% sensitivity and specificity). Our result demonstrated that CSF can be correctly distinguished from mepivacaine in patients undergoing cesarean section under single-space CSEA using a cutoff value of pH 7.1.

CONCLUSION

The pH test is a simple and reliable method to confirm CSF when performing single-space CSEA with mepivacaine for LOR.

TRIAL REGISTRATION

Accuracy of pH test paper for cerebrospinal fluid during spinal anesthesia: prospective study in healthy pregnant women under scheduled caesarean section; University Hospital Medical Information Network, UMIN000036454 . Registered 1 May 2019.

Mepivacaine versus Bupivacaine Spinal Anesthesia for Early Postoperative Ambulation

Background

Early ambulation after total hip arthroplasty predicts early discharge. Spinal anesthesia is preferred by many practices but can delay ambulation, especially with bupivacaine. Mepivacaine, an intermediate-acting local anesthetic, could enable earlier ambulation than bupivacaine. This study was designed to test the hypothesis that patients who received mepivacaine would ambulate earlier than those who received hyperbaric or isobaric bupivacaine for primary total hip arthroplasty.

Methods

This randomized controlled trial included American Society of Anesthesiologists Physical Status I to III patients undergoing primary total hip arthroplasty. The patients were randomized 1:1:1 to 52.5 mg of mepivacaine, 11.25 mg of hyperbaric bupivacaine, or 12.5 mg of isobaric bupivacaine for spinal anesthesia. The primary outcome was ambulation between 3 and 3.5 h. Secondary outcomes included return of motor and sensory function, postoperative pain, opioid consumption, transient neurologic symptoms, urinary retention, intraoperative hypotension, intraoperative muscle tension, same-day discharge, length of stay, and 30-day readmissions.

Results

Of 154 patients, 50 received mepivacaine, 53 received hyperbaric bupivacaine, and 51 received isobaric bupivacaine. Patient characteristics were similar among groups. For ambulation at 3 to 3.5 h, 35 of 50 (70.0%) of patients met this endpoint in the mepivacaine group, followed by 20 of 53 (37.7%) in the hyperbaric bupivacaine group, and 9 of 51 (17.6%) in the isobaric bupivacaine group (P &lt; 0.001). Return of motor function occurred earlier with mepivacaine. Pain and opioid consumption were higher for mepivacaine patients in the early postoperative period only. For ambulatory status, 23 of 50 (46.0%) of mepivacaine, 13 of 53 (24.5%) of hyperbaric bupivacaine, and 11 of 51 (21.5%) of isobaric bupivacaine patients had same-day discharge (P = 0.014). Length of stay was shortest in mepivacaine patients. There were no differences in transient neurologic symptoms, urinary retention, hypotension, muscle tension, or dizziness.

Conclusions

Mepivacaine patients ambulated earlier and were more likely to be discharged the same day than both hyperbaric bupivacaine and isobaric bupivacaine patients. Mepivacaine could be beneficial for outpatient total hip arthroplasty candidates if spinal is the preferred anesthesia type.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Spinal versus general anesthesia for outpatient joint arthroplasty: can the evidence keep up with the patients?

Total joint arthroplasty (TJA) is transitioning to be an outpatient rather than an inpatient procedure under national and institutional pressures to increase volumes while reducing hospital costs and length of stay. Innovative surgical and anesthesia techniques have allowed for earlier ambulation and physical therapy participation, maximizing the chance that an appropriately selected patient may be discharged within a day of surgery. The choice of anesthesia type is a modifiable factor that has a major impact on both surgical outcomes and discharge readiness. Recent large database studies have provided evidence for improved outcomes, including decreased mortality, with the use of spinal anesthesia. However, few randomized, controlled trials exist and database studies have limitations. Modern general anesthesia techniques, including total intravenous anesthesia and infusions targeted to anesthetic depth, may make some of these differences insignificant, especially when newer regional anesthesia and local infiltration analgesia techniques are incorporated into TJA enhanced recovery protocols. Multimodal analgesia for all TJA patients may also help minimize differences in pain. Perhaps even more important than anesthesia technique is the proper selection of patients likely to meet the necessary milestones for early discharge. In this article, we provide two contrasting viewpoints on the optimal primary anesthetic for outpatient TJA.

Lidocaine vs. Other Local Anesthetics in the Development of Transient Neurologic Symptoms (TNS) Following Spinal Anesthesia: A Meta-Analysis of Randomized Controlled Trials

The use of lidocaine in spinal anesthesia may increase the risk of transient neurological symptoms (TNS) according to previous meta-analyses. However, the previous meta-analyses lacked data on some other local anesthetics and thus, more evaluations are still needed to compare the effect of lidocaine on the development of TNS. The objective of this study was to compare the risk of TNS according to lidocaine versus other local anesthetics in patients undergoing spinal anesthesia. A total of 39 randomized controlled trials with 4733 patients were analyzed. The incidence of TNS was 10.8% in the lidocaine group and was 2.2% in the control groups (risk ratio (RR) 4.12, 95% confidence interval (CI) 3.13 to 5.43, p < 0.001). In subgroup analysis, lidocaine increased the incidence of TNS compared with other local anesthetics except mepivacaine, ropivacaine or sameridine. The risk of TNS was higher in the hyperbaric (p < 0.001) or isobaric lidocaine (p < 0.001) group compared with the control group, but there were no differences found between the two groups when hypobaric lidocaine was administered (p = 1.00). This study confirmed that lidocaine for spinal anesthesia still causes TNS more frequently than most other local anesthetics, especially when hyperbaric or isobaric lidocaine was used.

Transient neurological symptoms (TNS) following spinal anaesthesia with lidocaine versus other local anaesthetics in adult surgical patients: a network meta-analysis

BACKGROUND

Spinal anaesthesia has been implicated as one of the possible causes of neurological complications following surgical procedures. This painful condition, occurring during the immediate postoperative period, is termed transient neurological symptoms (TNS) and is typically observed after the use of spinal lidocaine. Alternatives to lidocaine that can provide high-quality anaesthesia without TNS development are needed. This review was originally published in 2005, and last updated in 2009.

OBJECTIVES

To determine the frequency of TNS after spinal anaesthesia with lidocaine and compare it with other types of local anaesthetics by performing a meta-analysis for all pair-wise comparisons, and conducting network meta-analysis (NMA) to rank interventions.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Elsevier Embase, and LILACS on 25 November 2018. We searched clinical trial registries and handsearched the reference lists of trials and review articles.

SELECTION CRITERIA

We included randomized and quasi-randomized controlled trials comparing the frequency of TNS after spinal anaesthesia with lidocaine to other local anaesthetics. Studies had to have two or more arms that used distinct local anaesthetics (irrespective of the concentration and baricity of the solution) for spinal anaesthesia in preparation for surgery. We included adults who received spinal anaesthesia and considered all pregnant participants as a subgroup. The follow-up period for TNS was at least 24 hours.

DATA COLLECTION AND ANALYSIS

Four review authors independently assessed studies for inclusion. Three review authors independently evaluated the quality of the relevant studies and extracted the data from the included studies. We performed meta-analysis for all pair-wise comparisons of local anaesthetics, as well as NMA. We used an inverse variance weighting for summary statistics and a random-effects model as we expected methodological and clinical heterogeneity across the included studies resulting in varying effect sizes between studies of pair-wise comparisons. The NMA used all included studies based on a graph theoretical approach within a frequentist framework. Finally, we ranked the competing treatments by P scores.

MAIN RESULTS

The analysis included 24 trials reporting on 2226 participants of whom 239 developed TNS. Two studies are awaiting classification and one is ongoing. Included studies mostly had unclear to high risk of bias. The NMA included 24 studies and eight different local anaesthetics; the number of pair-wise comparisons was 32 and the number of different pair-wise comparisons was 11. This analysis showed that, compared to lidocaine, the risk ratio (RR) of TNS was lower for bupivacaine, levobupivacaine, prilocaine, procaine, and ropivacaine with RRs in the range of 0.10 to 0.23 while 2-chloroprocaine and mepivacaine did not differ in terms of RR of TNS development compared to lidocaine. Pair-wise meta-analysis showed that compared with lidocaine, most local anaesthetics were associated with a reduced risk of TNS development (except 2-chloroprocaine and mepivacaine) (bupivacaine: RR 0.16, 95% confidence interval (CI) 0.09 to 0.28; 12 studies; moderate-quality evidence; 2-chloroprocaine: RR 0.09, 95% CI 0.01 to 1.51; 2 studies; low-quality evidence; levobupivacaine: RR 0.13, 95% CI 0.02 to 0.69; 2 studies; low-quality evidence; mepivacaine: RR 1.01, 95% CI 0.18 to 5.82; 4 studies; very low-quality evidence; prilocaine: RR 0.18, 95% CI 0.07 to 0.49; 4 studies; moderate-quality evidence; procaine: RR 0.14, 95% CI 0.04 to 0.52; 2 studies; moderate-quality evidence; ropivacaine: RR 0.10, 95% CI 0.01 to 0.78; 2 studies; low-quality evidence). We were unable to perform any of our planned subgroup analyses due to the low number of TNS events.

AUTHORS' CONCLUSIONS

Results from both NMA and pair-wise meta-analysis indicate that the risk of developing TNS after spinal anaesthesia is lower when bupivacaine, levobupivacaine, prilocaine, procaine, and ropivacaine are used compared to lidocaine. The use of 2-chloroprocaine and mepivacaine had a similar risk to lidocaine in terms of TNS development after spinal anaesthesia. Patients should be informed of TNS as a possible adverse effect of local anaesthesia with lidocaine and the choice of anaesthetic agent should be based on the specific clinical context and parameters such as the expected duration of the procedure and the quality of anaesthesia. Due to the very low- to moderate-quality evidence (GRADE), future research efforts in this field are required to assess alternatives to lidocaine that would be able to provide high-quality anaesthesia without TNS development. The two studies awaiting classification and one ongoing study may alter the conclusions of the review once assessed.

Using chloroprocaine for spinal anaesthesia in outpatient knee-arthroscopy results in earlier discharge and improved operating room efficiency compared to mepivacaine and prilocaine

PURPOSE

Knee arthroscopies are regularly carried out in an outpatient setting. The purpose of this retrospective analysis was to investigate the impact of different local anaesthetics for spinal anaesthesia on operating room efficiency (perioperative process times) and postoperative recovery. This study aims to determine the optimal LA for SPA in patients undergoing knee arthroscopy at a day-surgery centre.

METHODS

Anaesthesia records of all patients undergoing knee arthroscopy under spinal anaesthesia from 2010 until 2017 were analysed. Patients were categorised as having received spinal anaesthesia with prilocaine, mepivacaine or chloroprocaine.

RESULTS

Three-hundred and nine patients were included. Postoperative recovery was significantly faster for chloroprocaine 1% compared with both other local anaesthetics regarding all stages of recovery until discharge. Perioperative processes and surgery time were significantly shorter when chloroprocaine was used. Early postoperative pain occurred more frequently and earlier after spinal anaesthesia with chloroprocaine. Nevertheless, pain intensity did not differ between groups.

CONCLUSION

Spinal anaesthesia provides reliable blocks for outpatient knee arthroscopy. Considerations on the choice of local anaesthetic for spinal anaesthesia must include not only the recovery profile, but also the impact on operating room efficiency. Due to a superior recovery profile, low incidences of adverse side effects and raised operating room efficiency, chloroprocaine is the recommendable local anaesthetic for spinal anaesthesia in patients undergoing knee arthroscopy in an ambulatory setting. Since the frequency of SPA in patients undergoing outpatient knee arthroscopy is rising yearly, the results of this study are of high clinical relevance. The use of chloroprocaine leads to improved recovery, optimized perioperative processes and consecutively to a raised OR efficiency.

LEVEL OF EVIDENCE

III.

Time of return of neurologic function after spinal anesthesia for total knee arthroplasty: mepivacaine vs bupivacaine in a randomized controlled trial

Background

Mepivacaine as an intermediate-length spinal anesthetic for rapid recovery in total knee arthroplasty (TKA) has not been fully described. We compared spinal mepivacaine vs bupivacaine for postoperative neurologic function in patients undergoing primary TKA.

Methods

Thirty-two patients undergoing primary TKA were enrolled. Primary outcome measure was return of motor and sensory function. Secondary outcome measures included assessment of urinary function, pain via visual analog scale (VAS) scores, opioid usage, distance walked and pain with physical therapy, time to discharge readiness, and complications.

Results

Patients with mepivacaine spinal anesthetic had faster return of sensory function (164 ± 38.6 vs 212 ± 54.2 minutes, P = .015), return of motor function (153 ± 47.4 vs 200 ± 45.2 minutes, P = .025), and time to straight leg raise (148 ± 43.5 vs 194 ± 50.8 minutes, P = .023). The mepivacaine group experienced significantly fewer episodes of urinary retention and shorter time to urination (344 ± 154.4 vs 416 ± 96.3 minutes, P = .039). Patients exhibited slightly higher VAS pain scores in the postanesthesia care unit (1.0 ± 1.7 vs 2.7 ± 2.3, P = .046) with no difference in opioid consumption. There were no differences in VAS scores or opioid use on the inpatient ward. Patients achieved discharge readiness 71 minutes faster in the mepivacaine group. There was no need to convert to general anesthesia or transient nerve symptoms in either group.

Conclusions

Patients undergoing TKA with mepivacaine spinal anesthetic had a reliably more rapid neurologic recovery after TKA compared to bupivacaine.

Mepivacaine Spinal Anesthesia Facilitates Rapid Recovery in Total Knee Arthroplasty Compared to Bupivacaine

BACKGROUND

Mepivacaine as a spinal anesthetic for rapid recovery in total knee arthroplasty (TKA) has not been assessed. The purpose of this study is to compare spinal mepivacaine vs bupivacaine for postoperative measures in patients undergoing primary TKA.

METHODS

Retrospective review of a prospectively collected single-institution database was performed on 156 consecutive patients who underwent primary TKA. Fifty-three patients were administered mepivacaine and 103 patients were administered bupivacaine. Primary outcomes were urinary retention, length of stay, pain control, opioid consumption, and distance associated with physical therapy. Statistical analysis with univariate logistic regression was performed to evaluate the effect of anesthetic with primary outcomes.

RESULTS

Patients undergoing TKA with mepivacaine had a shorter length of stay (28.1 ± 11.2 vs 33.6 ± 14.4 hours, P = .002) and fewer episodes of straight catheterization (3.8% vs 16.5%, P = .021) compared to bupivacaine. Patients administered mepivacaine exhibited slightly higher VAS pain scores and morphine consumption in the postanesthesia care unit (1.3 ± 1.9 vs 0.5 ± 1.3, P = .002; 2.2 ± 3.3 vs 0.8 ± 2.1 equivalents/h, P = .002), but otherwise exhibited no difference in VAS scores or morphine consumption afterwards. There was no need to convert to general anesthesia or transient neurologic symptom complication in either group.

CONCLUSION

Mepivacaine for spinal anesthesia with TKA had adequate duration to complete the surgery and facilitated a more rapid recovery with less urinary complications and a shorter length of stay. Patients administered mepivacaine did not display worse pain control or transient neurologic symptoms afterwards.

Transient Neurologic Symptoms following Spinal Anesthesia with Isobaric Mepivacaine: A Decade of Experience at Toronto Western Hospital

Background

Transient neurologic symptoms (TNSs) can be distressing for patients and providers following uneventful spinal anesthesia. Spinal mepivacaine may be less commonly associated with TNS than lidocaine; however, reported rates of TNS with intrathecal mepivacaine vary considerably.

Materials and Methods

We conducted a retrospective cohort study reviewing the internal medical records of surgical patients who underwent mepivacaine spinal anesthesia at Toronto Western Hospital over the last decade to determine the rate of TNS. We defined TNS as new onset back pain that radiated to the buttocks or legs bilaterally.

Results

We found one documented occurrence of TNS among a total of 679 mepivacaine spinal anesthetics (0.14%; CI: 0.02-1.04%) that were performed in 654 patients.

Conclusion

Our retrospective data suggest that the rate of TNS associated with mepivacaine spinal anesthesia is lower than that previously reported in the literature.

Effects of sodium bisulfite with or without procaine derivatives on axons of cultured mouse dorsal root ganglion neurons

BACKGROUND AND OBJECTIVES

Sodium bisulfite (NaHSO3) was clinically used as a preservative agent for local anesthetics but was later suspected to be neurotoxic. However, recent studies reported that NaHSO3 reduces the neurotoxicity of local anesthetics. The purpose of this study was to examine the effects of NaHSO3 with and without procaine on axonal transport in cultured mouse dorsal root ganglion (DRG) neurons.

METHODS

Experiment 1 served to determine the dose-dependent effects of NaHSO3 on axonal transport (DRG neurons were treated with 0.01, 0.1, 1, 10, or 20 mM of NaHSO3), whereas experiment 2 investigated the effect of 0.1 mM NaHSO3 on the action of local anesthetics on axonal transport (DRG neurons were treated with 1 mM procaine alone, or with 0.1 mM NaHSO3 plus 1 mM procaine). As an additional experiment, DRG neurons were also treated with 1 mM chloroprocaine alone, or with 0.1 mM NaHSO3 plus 1 mM chloroprocaine. In these experiments, we analyzed the percent change in the number of anterogradely and retrogradely transported organelles and recorded changes in neurite morphology using video-enhanced microscopy.

RESULTS

In experiment 1, NaHSO3 at more than 1 mM caused cell membrane damage and complete inhibition of axonal transport, whereas 0.1 mM NaHSO3 maintained axonal transport at 40% to 60% of control with intact cell membrane. In experiment 2, 1 mM procaine alone maintained axonal transport at 90% to 100%. However, application of 1 mM procaine-0.1 mM NaHSO3 solution resulted in deformation of neurites and with complete cessation of axonal transport. Likewise, although 1 mM chloroprocaine maintain axonal transport at 80% to 100%, 1 mM chloroprocaine-0.1 mM NaHSO3 arrested axonal transport.

CONCLUSIONS

NaHSO3 resulted in a dose-dependent damage to the cell membrane and axonal transport, especially when used in combination with procaine or chloroprocaine.

Spinal mepivacaine with fentanyl for outpatient knee arthroscopy surgery: a randomized controlled trial

BACKGROUND

The foremost limitation of local anesthetic solutions for spinal anesthesia in the outpatient setting is prolonged motor blockade and delayed ambulation. The purpose of this study was to determine if the addition of intrathecal fentanyl to low-dose spinal mepivacaine provides adequate anesthesia with shorter duration of functional motor blockade for ambulatory knee surgery compared with spinal mepivacaine alone.

METHODS

Following institutional review board approval and informed consent, 34 patients undergoing unilateral knee arthroscopy were enrolled in this study. The patients were randomly assigned to receive either 30 mg of isobaric mepivacaine 1.5% plus fentanyl 10 microg (M + F group) or 45 mg of isobaric mepivacaine 1.5% alone (M group) intrathecally. Postoperatively, the times to achieve sensory block regression to the S1 dermatome and to attain functional motor block recovery enabling ambulation were recorded. All assessments were blinded.

RESULTS

The time to completion of Phase I recovery was shorter in the M + F group (104.6 +/- 28.4 min) than in the M group (129.1 +/- 30.4 min; P = 0.023). Regression of sensory blockade to S1 was earlier in the M + F group (118.4 +/- 53.5 min) than in the M group (169.7 +/- 38.9 min; P = 0.003). Patients in the M + F group (176.4 +/- 40.3 min) were able to ambulate significantly earlier than those in the M group (205.6 +/- 31.4 min; P = 0.025). No cases of transient or persistent neurological dysfunction were noted.

CONCLUSIONS

When compared with 45 mg isobaric mepivacaine 1.5%, an intrathecal dose of 30 mg isobaric mepivacaine 1.5% plus 10 microg fentanyl produces reliable anesthesia, hastens block regression, shortens stay in Phase I recovery, and enables earlier ambulation for patients undergoing unilateral knee arthroscopy (Registration no. NCT00803725).

Transient neurologic symptoms (TNS) following spinal anaesthesia with lidocaine versus other local anaesthetics

BACKGROUND

Spinal anaesthesia has been in use since 1898. During the last decade there has been an increase in the number of reports implicating lidocaine as a possible cause of temporary and permanent neurologic complications after spinal anaesthesia. Follow up of patients who received uncomplicated spinal anaesthesia revealed that some of them developed pain in the lower extremities after an initial full recovery. This painful condition that occurs in the immediate postoperative period was named 'transient neurologic symptoms' (TNS).

OBJECTIVES

To study the frequency of TNS and neurologic complications after spinal anaesthesia with lidocaine compared to other local anaesthetics.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials Register (CENTRAL) (The Cochrane Library, Issue 4, 2008); MEDLINE (1966 to August 2008); EMBASE (1980 to week 35, 2008); LILACS (August 2008); and handsearched the reference lists of trials and review articles.

SELECTION CRITERIA

We included all randomized and quasi-randomized studies comparing the frequency of TNS and neurologic complications after spinal anaesthesia with lidocaine as compared to other local anaesthetics.

DATA COLLECTION AND ANALYSIS

Two authors independently evaluated the quality of the relevant studies and extracted the data from the included studies.

MAIN RESULTS

Sixteen trials reporting on 1467 patients, 125 of whom developed TNS, were included in the analysis. The use of lidocaine for spinal anaesthesia increased the risk of developing TNS. There was no evidence that this painful condition was associated with any neurologic pathology; the symptoms disappeared spontaneously by the fifth postoperative day. The relative risk (RR) for developing TNS after spinal anaesthesia with lidocaine as compared to other local anaesthetics (bupivacaine, prilocaine, procaine, levobupivacaine, ropivacaine, and 2-chloroprocaine) was 7.31 (95% confidence interval (CI) 4.16 to 12.86). Mepivacaine was found to give similar results as lidocaine and was therefor omitted from the overall comparison to diminish the heterogeneity.

AUTHORS' CONCLUSIONS

The risk of developing TNS after spinal anaesthesia with lidocaine was significantly higher than when bupivacaine, prilocaine, or procaine were used. The term 'transient neurological symptoms' implies neurologic pathology. Failing identification of the pathogenesis of TNS, consideration should be given to choosing a neutral descriptive term which does not imply a particular causation. One study about the impact of TNS on patient satisfaction and functional impairment demonstrated that non-TNS patients were more satisfied and had less functional impairment after surgery than TNS patients, but this did not influence their willingness to recommend spinal anaesthesia.

Transient neurological symptoms after isobaric subarachnoid anesthesia with 2% lidocaine: the impact of needle type

BACKGROUND

The reported incidence of transient neurological symptoms (TNS) after subarachnoid lidocaine administration is as high as 40%. We designed this clinical trial to determine the incidence of TNS with two different pencil-point spinal needles: one-orifice (Atraucan) and two-orifice (Eldor) spinal needles.

METHODS

Ninety-nine ASA physical status I or II patients undergoing surgical procedures of the urinary bladder or prostate were prospectively allocated to receive spinal anesthesia with 40 mg, 2% isobaric lidocaine plus fentanyl injected through either a 26-gauge Atraucan (n = 52) or a 26-gauge Eldor (n = 47) spinal needle. During the first three postoperative days, patients were observed for postoperative complications, including TNS. The primary end-point for this trial was the percentage of TNS in both double- and single-orifice spinal needle procedures.

RESULTS

The incidence of TNS was higher when spinal anesthesia was done through the Atraucan needle (28.8% vs 8.5%, P = 0.006). Fifty percent of the patients in the double-orifice group versus 100% of the single-orifice group developed TNS after surgery in the lithotomy position (P = 0.014). The relative risk for developing TNS with the Eldor needle was 0.29 (95% CI: 0.07-0.75) compared with the Atraucan needle.

CONCLUSIONS

The use of a double-orifice spinal needle was associated with a lower incidence of TNS, which may have been due to the needle design.

Postoperative analgesia requirements at home after inguinal hernia repair: effects of wound infiltration on postoperative pain*

The aim of this study was to evaluate our postoperative pain protocol after ambulatory herniorrhaphy and to determine how infiltration with local anaesthetics would add to our management of postoperative pain. Two groups of 60 patients, scheduled for herniorrhaphy, received wound infiltration with 20 ml levobupivacaine 0.5% or saline 0.9%. Postoperatively, the patients regulated their own analgesic consumption and registered VAS scores, use of analgesics and side-effects in a diary for 5 days. The median time to first analgesic, the pain visual analogue scale scores, number of patients using no analgesic and the use of analgesic medication were significantly lower in the levobupivacaine group in the first 24 h, but not thereafter. Most patients used acetaminophen in the first 5 days after surgery and occasionally diclofenac. Only a minority used tramadol. Our multimodal pain protocol achieved reasonable results at rest, but a considerable number of patients experienced moderate to severe pain with movement.

A comparison of spinal anesthesia with small-dose lidocaine and general anesthesia with fentanyl and propofol for ambulatory prostate biopsy procedures in elderly patients

STUDY OBJECTIVE

To compare operating conditions, intraoperative adverse events, recovery profiles, postoperative adverse effects, patient satisfaction, and costs of small-dose lidocaine spinal anesthesia with those of general anesthesia using fentanyl and propofol for elderly outpatient prostate biopsy.

DESIGN

Prospective, randomized, blind study.

SETTING

Outpatient anesthesia unit at a municipal hospital.

PATIENTS

80 ASA physical status I and II patients, aged 65 to 80 years, scheduled for outpatient prostate biopsy.

INTERVENTIONS

Patients were assigned to receive either spinal anesthesia with 10 mg of hyperbaric 1% lidocaine (L group, n=40) or anesthetic induction with fentanyl 1 microg.kg-1 IV and 1.0 mg.kg-1 propofol injected at 90 mg.kg-1.h-1, followed by continuous infusion at 6 mg.kg-1.h-1 (F/P group, n=40).

MEASUREMENTS AND MAIN RESULTS

Both anesthetic techniques provided acceptable operating conditions for the surgeon. However, a significantly higher frequency of intraoperative hypotension was found in the F/P group than in the L group (P<0.05). Time to home readiness was shorter in the F/P group (P<0.05). Both techniques had no major postoperative adverse effects and resulted in a high rate of patient satisfaction. Total costs were significantly lower in the L group than in the F/P group (P<0.01).

CONCLUSIONS

Spinal anesthesia with 10 mg of hyperbaric 1% lidocaine may be a more suitable alternative to general anesthesia with fentanyl and propofol for ambulatory elderly prostate biopsy in terms of safety and costs.

Transient neurologic symptoms (TNS) following spinal anaesthesia with lidocaine versus other local anaesthetics

BACKGROUND

Spinal anaesthesia has been in use since the turn of the late nineteenth century. During the last decade there has been an increase in the number of reports implicating lidocaine as a possible cause of temporary and permanent neurologic complications after spinal anaesthesia. Follow-up of patients who received uncomplicated spinal anaesthesia revealed that some of them developed pain in the lower extremities after an initial full recovery. This painful condition that occurs in the immediate postoperative period was named "transient neurologic symptoms" (TNS).

OBJECTIVES

To study the frequency of TNS and neurologic complications after spinal anaesthesia with lidocaine, compared to other local anaesthetics.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register (CENTRAL), (The Cochrane Library, Issue 1, 2005); MEDLINE (1966 to January 2005); EMBASE (1980 to week 6, 2005); LILACS (March 2005); and handsearched the reference lists of trials and review articles.

SELECTION CRITERIA

We included all randomized and pseudo-randomized studies comparing the frequency of TNS and of neurologic complications after spinal anaesthesia with lidocaine as compared to other local anaesthetics.

DATA COLLECTION AND ANALYSIS

Two authors independently evaluated the quality of the relevant studies and extracted the data from the included studies.

MAIN RESULTS

Fifteen trials, reporting 1437 patients, 120 of whom developed transient neurologic symptoms, were included in the analysis. The use of lidocaine for spinal anaesthesia increased the risk of developing TNS. There was no evidence that this painful condition was associated with any neurologic pathology; the symptoms disappeared spontaneously by the fifth postoperative day. The relative risk (RR) for developing TNS after spinal anaesthesia with lidocaine as compared to other local anaesthetics (bupivacaine, prilocaine, procaine, levobupivacaine and ropivacaine) was 7.16 (95% confidence interval (CI) 4.02, 12.75).

AUTHORS' CONCLUSIONS

The risk of developing TNS after spinal anaesthesia with lidocaine was significantly higher than when bupivacaine, prilocaine and procaine were used. The term "TNS", which implies a positive neurologic finding, should not be used for this painful condition. One study about the impact of TNS on patient satisfaction and functional impairment demonstrated that non-TNS patients were more satisfied and had less functional impairment after surgery than TNS patients, but this did not influence their willingness to recommend spinal anaesthesia.

The Incidence of Transient Neurologic Symptoms After Spinal Anesthesia with Mepivacaine

We prospectively evaluated 1273 patients who received spinal (or combined spinal-epidural [CSE]) anesthesia with 1.5% mepivacaine (plain, no glucose) for ambulatory surgery. We hypothesized that analysis of a large series of patients would confirm previous findings that isobaric 1.5% mepivacaine is not frequently associated with transient neurologic symptoms (TNS). Patients were contacted twice after the anesthetic, at days 1-4 and days 6-9. One-thousand-two-hundred-ten patients were successfully contacted postoperatively (95% follow-up rate). None of the patients had permanent neurologic sequelae from the anesthetic. None of the 372 CSE anesthetics was inadequate for surgery. Fourteen of 838 (1.7%) of the spinal anesthetics were inadequate. TNS, defined as the new onset of back pain that radiated bilaterally to buttocks or distally, occurred in 78 patients (6.4%; 95% confidence intervals 5.1%-8%). The mean age of patients who developed TNS (48 +/- 14 yr) was older than that of patients without TNS (41 +/- 16 yr) (P < 0.001). TNS was not influenced by gender or intraoperative position. The frequent success rate and infrequent rates of complications such as TNS and postdural puncture headache suggest that spinal anesthesia with mepivacaine is likely to be a safe and effective anesthetic for ambulatory patients.

Transient Neurologic Symptoms After Spinal Anesthesia with Lidocaine Versus Other Local Anesthetics: A Systematic Review of Randomized, Controlled Trials

Lidocaine has been used for spinal anesthesia since 1948, seemingly without causing concern. However, during the last 10 years, a number of reports have appeared implicating lidocaine as a possible cause of neurologic complications after spinal anesthesia. Follow-up of patients who received uncomplicated spinal anesthesia revealed that some of them developed pain in the lower extremities--transient neurologic symptoms (TNS). In this study, we sought to compare the frequency of 1) TNS and 2) neurologic complications after spinal anesthesia with lidocaine with that after other local anesthetics. Published trials were identified by computerized searches of The Cochrane Library, MEDLINE, LILAC, and EMBASE and by checking the reference lists of trials and review articles. The search identified 14 trials reporting 1347 patients, 117 of whom developed TNS. None of these patients showed signs of neurologic complications. The relative risk for developing TNS after spinal anesthesia with lidocaine was higher than with other local anesthetics (bupivacaine, prilocaine, procaine, and mepivacaine), i.e., 4.35 (95% confidence interval, 1.98-9.54). There was no evidence that this painful condition was associated with any neurologic pathology; in all patients, the symptoms disappeared spontaneously by the 10th postoperative day.

Anaesthetic Agents for Advanced Regional Anaesthesia

Interest in the use of regional anaesthesia, particularly peripheral nerve blocks (PNBs) and continuous PNBs, has increased in recent years. Accompanying this resurgence in interest has been the development of new local anaesthetics and additives designed to enhance block duration and quality. This manuscript provides a literature-based review on accepted uses of local anaesthetics and adjuncts for a variety of regional anaesthesia techniques. A brief review of local anaesthetic pharmacodynamics describes the action of these drugs in preventing nerve depolarisation, thus blocking nerve impulses. Toxic adverse effects of local anaesthetics, specifically CNS and cardiac manifestations of excessive local anaesthetic blood concentrations and the direct neurotoxic properties of local anaesthetics, are discussed generally and specifically for many commonly used local anaesthetics. Clinically useful ester and amide local anaesthetics are evaluated individually in terms of their physical properties and toxic potential. How these properties impact on the clinical uses of each local anaesthetic is explored. Particular emphasis is placed on the long-acting local anaesthetic toxic potential of racemic bupivacaine compared with levobupivacaine and ropivacaine, which are both levorotatory stereoisomers. Guidelines for using ropivacaine and mepivacaine, based on the authors' experience using advanced regional anaesthesia in a busy practice, is provided. Finally, epinephrine (adrenaline), clonidine and other local anaesthetic additives and their rationale for use is covered along with other future possibilities.

Transient neurological syndrome: does it really exist?

PURPOSE OF REVIEW

Subarachnoid injection of local anesthetics has been related to the appearance of transient neurological symptoms (called transient neurologic syndrome), as reflected by a number of clinical reports showing their incidence in clinical practice. However, the etiology of this syndrome is virtually unknown, as is the number of factors implicated in its development. This review will attempt to clarify this entity and its relationship with spinal anesthesia.

RECENT FINDINGS

Intrathecal administration of local anesthetics is known to increase glutamate concentration in cerebrospinal fluid and histopathologic changes of motor neurons in the lumbar spinal cord, suggesting damage of dorsal and ventral roots. In-vitro studies of cultured neurons exposed to different concentrations of local anesthetics have shown changes in growth of cones and neurites, which may be related to transient neurologic syndrome.

SUMMARY

The latest studies show biochemical and anatomopathologic changes that support the structural basis of the existence of transient neurologic syndrome. In the authors' view, transient neurologic syndrome could represent the lower end of a spectrum of local anesthetic toxicity. Recent findings demonstrate that nerve membrane damage induced by highly concentrated local anesthetics such as lidocaine, tetracaine, dibucaine and procaine may generate irreversible neural injury. Still further studies are needed to establish the relationship between morphological changes induced in vitro and the occurrence of clinical symptoms.

Neurotoxicity of intrathecal local anaesthetics and transient neurological symptoms

Local anaesthetics have been placed in the intrathecal space for approximately 100 years. Currently used intrathecal local anaesthetics appear to be relatively benign on the basis of the low incidence of permanent neurological deficits. In large retrospective surveys of 4000-10 000 patients, the incidence of persistent neurological sequelae after subarachnoid anaesthesia varies between 0.01 and 0.7%. Since its introduction in 1948, hyperbaric 5% lidocaine has been used for millions of spinal anaesthetics. The predictable onset and limited duration of action have made lidocaine one of the most popular spinal anaesthetics currently available. Concern about the use of spinal lidocaine began in 1991 with published reports of cauda equina syndrome after continuous spinal anaesthesia. In 1993, Schneider published a case report of four patients undergoing spinal anaesthesia who postoperatively experienced aching and pain in the buttocks and lower extremities. This chapter reviews the neurotoxicity of spinal local anaesthetics, as well as the incidence, possible aetiology, and treatment of transient neurological symptoms after lidocaine spinal anaesthesia.

Regional Anaesthesia in the Elderly

The number of elderly patients presenting for anaesthesia and surgery has increased exponentially in recent years. Regional anaesthesia is frequently used in elderly patients undergoing surgery. Although the type of anaesthesia (general versus regional anaesthesia) has no substantial effect on perioperative morbidity and mortality in any age group; it intuitively makes sense that elderly patients would benefit from regional anaesthesia because they remain minimally sedated throughout the procedures and awaken with excellent postoperative pain control. However, a multitude of factors influence the outcome, such as the type, duration and invasiveness of the operation, co-existing medical and mental status of the patient and the skill and expertise of the anaesthesiologist and surgeon. These factors make it difficult to decide if and when one technique is equivocally better than another. Thus, it is more important to optimise the overall management of the patient during the perioperative period and, in most cases, it is the quality of the anaesthetic administered rather than the type of anaesthetic which is most important. Sedatives used for regional anaesthesia in the elderly should be short acting, easy to administer, have a low adverse effect profile and high safety margin. Midazolam, lorazepam, ketamine, propofol and low-dose opioids have been successfully used for sedation in the elderly. Aging affects the pharmacokinetics and pharmacodynamics of local anaesthetics, composition and characteristics of tissues and organs within the body, and physiological functions of the body. Changes in the systematic absorption, distribution and clearance of local anaesthetics lead to an increased sensitivity, decreased dose requirement and a change in the onset and duration of action in the elderly. Decreases in neural population, neural conduction velocity and inter-Schwann cell distance can lead to an increased sensitivity to local anaesthetics in the elderly. The addition of an opioid and epinephrine (adrenaline) has been shown to be useful in central neuraxial blockade. Epinephrine also can prolong the duration of peripheral nerve blocks. However, caution must be exercised as epinephrine has the potential for causing ischaemic neurotoxicity in peripheral nerves. Regional anaesthesia appears to be safe and beneficial in elderly patients; however, every anaesthetic administered must be assessed on a case-by-case basis and particular consideration should be given to the health status of the patient, the operation being performed and the expertise of the anaesthesiologist.

Spinal anaesthesia for outpatient surgery

Spinal anaesthesia in the outpatient is characterized by rapid onset and offset, easy administration, minimal expense, and minimal side effects or complications. Spinal anaesthesia offers advantages for outpatient lower extremity, perineal, and many abdominal and gynaecological procedures. Development of small-gauge, pencil-point needles are responsible for the success of outpatient spinal anaesthesia with acceptable rates (0-2%) of postdural puncture headache (PDPH). Compared with peripheral nerve blocks, spinal anaesthesia has a more predictable offset. There are many possible choices of local anaesthetics for outpatient spinal anaesthesia. These include lidocaine, prilocaine, mepivacaine and small doses of bupivacaine. Meperidine has local anaesthetic properties in addition to its opiate properties. It has been used as the sole intrathecal agent for spinal anaesthesia but has no real advantages over lidocaine. Mepivacaine and lidocaine have each been associated with transient neurological symptoms (TNS) following intrathecal administration. This has stimulated development of alternative agents, including combinations of local anaesthetics and opioids. Lidocaine remains the most useful agent for outpatient spinal anaesthesia. For longer procedures, mepivacaine is an excellent spinal anaesthetic agent. Attention to technique, reduction of dose and addition of fentanyl to lidocaine result in effective spinal anaesthesia with rapid recovery and a low incidence of significant side effects or complications.

Procaine and mepivacaine have less toxicity in vitro than other clinically used local anesthetics

The neurotoxicity of local anesthetics can be demonstrated in vitro by the collapse of growth cones and neurites in cultured neurons. We compared the neurotoxicity of procaine, mepivacaine, ropivacaine, bupivacaine, lidocaine, tetracaine, and dibucaine by using cultured neurons from the freshwater snail Lymnaea stagnalis. A solution of local anesthetics was added to the culture dish to make final concentrations ranging from 1 x 10(-6) to 2 x 10(-2) M. Morphological changes in the growth cones and neurites were observed and graded 1 (moderate) or 2 (severe). The median concentrations yielding a score of 1 were 5 x 10(-4) M for procaine, 5 x 10(-4) M for mepivacaine, 2 x 10(-4) M for ropivacaine, 2 x 10(-4) M for bupivacaine, 1 x 10(-4) M for lidocaine, 5 x 10(-5) M for tetracaine, and 2 x 10(-5) M for dibucaine. Statistically significant differences (P < 0.05) were observed between mepivacaine and ropivacaine, bupivacaine and lidocaine, lidocaine and tetracaine, and tetracaine and dibucaine. The order of neurotoxicity was procaine = mepivacaine < ropivacaine = bupivacaine < lidocaine < tetracaine < dibucaine. Although lidocaine is more toxic than bupivacaine and ropivacaine, mepivacaine, which has a similar pharmacological effect to lidocaine, has the least-adverse effects on cone growth among clinically used local anesthetics.

IMPLICATIONS

Systematic comparison was assessed morphologically in growth cones and neurites exposed to seven local anesthetics. The order of neurotoxicity was procaine = mepivacaine < ropivacaine = bupivacaine < lidocaine < tetracaine < dibucaine. Although lidocaine is more toxic than bupivacaine and ropivacaine, mepivacaine, which has a similar pharmacological effect to lidocaine, is the safest among clinically used local anesthetics.

Postoperative recovery and discharge

Ambulatory surgery provides quality care that is cost-effective. The use of innovative surgical and anesthetic techniques will allow larger numbers of patients to take advantage of the benefits of undergoing an elective operation on an ambulatory basis. Anesthesiologists will be faced with more complex surgery, which will require careful selection and assessment of patients to ensure continuity of the excellent safety record of ambulatory anesthesia. Minor adverse events, such as pain and PONV, are still common. The occurrence of these minor adverse advents is now the major area of quality assessment and an area where improvement could be targeted. Fast tracking facilitates earlier discharge, but we must ensure this has benefit to the patient as speedy discharge may mask the true incidence of adverse minor symptoms. This can lead to patient dissatisfaction and a poor impression of ambulatory surgery.

Urinary bladder scanning after day-case arthroscopy under spinal anaesthesia: comparison between lidocaine, ropivacaine, and levobupivacaine

BACKGROUND

Micturition problems after spinal anaesthesia may delay hospital discharge. The use of lidocaine has raised concerns because of the occurrence of transient neurological symptoms (TNS). This randomized double-blind study was designed to compare the newer local anaesthetics with lidocaine regarding block characteristics, micturition problems, and discharge times in day-case spinals for arthroscopy.

METHODS

Ninety patients received either isobaric lidocaine 60 mg, ropivacaine 15 mg, or levobupivacaine 10 mg intrathecally. Urinary bladder volumes were measured by ultrasound imaging at regular time intervals until a post-voiding residual volume (PVRV) less than 100 ml was obtained. Micturition problems were classified in five groups ranging from no problems to those requiring catheterization.

RESULTS

Times to regain a Bromage-1 and -0 motor block were similar in the three groups but sensory block regression to L2 occurred at 145 (30) min in the lidocaine group, 25-30 min (P<0.05) faster than the other groups. Lidocaine allowed voiding after 245 (65) min and hospital discharge 265 (70) min after spinal injection, 40 min faster than in the two other groups. The incidence or degree of micturition problems were not different between after discharge, three patients (10%) receiving lidocaine complained of symptoms compatible with TNS.

CONCLUSIONS

Our study suggested that the three local anaesthetics behave similar regarding quality of anaesthesia and motor block but voiding and discharge occurred significantly earlier with lidocaine although the 40 min difference was not impressive considering a spinal discharge time interval of 4-5 h.

Intrathecal fentanyl, sufentanil, or placebo combined with hyperbaric mepivacaine 2% for parturients undergoing elective cesarean delivery

Worldwide, long-acting bupivacaine is the most popular local anesthetic for spinal anesthesia in parturients undergoing elective cesarean delivery. With advances in surgical techniques, e.g., the Misgav Ladach method, and shorter duration of surgery, the local anesthetic mepivacaine, with an intermediate duration of action, may be a reasonable alternative. Our aim in the present study was to evaluate the effects of 2% hyperbaric mepivacaine alone, or combined with either intrathecal fentanyl (5 and 10 microg), or sufentanil (2.5 and 5 microg), on sensory, motor, and analgesic block characteristics, hemodynamic variables, and neonatal outcome in a randomized, prospective, and double-blinded study (n = 100, 20 parturients per group, singleton pregnancy, >37 wk of gestation). No parturient experienced intraoperative pain. The average duration of motor block Bromage 3 in all groups was 68 min, and resolution time to Bromage 0 was 118 min. Maximal cephalad sensory block level was T3-6 and could be established within 6 min. Complete analgesia was significantly prolonged in all groups receiving intrathecal opioids, yet, with sufentanil 5 microg, even the duration of effective analgesia was significantly extended. Neonatal outcome was not affected by intrathecal opioid administration. In conclusion, 2% hyperbaric mepivacaine is a feasible local anesthetic for spinal anesthesia in parturients undergoing elective cesarean delivery, particularly with short duration of surgery.

IMPLICATIONS

Sensory, motor, and analgesic block characteristics of the local anesthetic mepivacaine alone or combined with intrathecal opioids were studied in parturients undergoing elective cesarean delivery in a randomized, double-blinded clinical trial. Mepivacaine was found to be an acceptable local anesthetic for spinal anesthesia in parturients undergoing cesarean delivery. In combination with sufentanil 5 microg, complete and effective analgesia were significantly prolonged.

Analgesic, behavioral, and hemodynamic and respiratory effects of midsacral subarachnoidally administered ropivacaine hydrochloride in mares

OBJECTIVE

To determine the analgesic, behavioral, hemodynamic and respiratory effects of midsacral subarachnoid administration of ropivacaine hydrochloride solution in mares.

STUDY DESIGN

Randomized, blinded study.

ANIMALS

Ten healthy mares, weighing from 470 to 560 kg.

METHODS

Intravascular and subarachnoid catheters were placed after infiltration of the skin and subcutaneous tissues with 2% lidocaine. Ropivacaine (0.2%, 5 mL) or 0.9% NaCl was then administered subarachnoidally at the midsacral (S2-S3) vertebrae. Analgesia was determined by lack of sensory perception to electrical stimulation (>40 mA) and absence of response to needle pricks extending from coccygeal to S1 dermatomes. Numerical scores of sedation, change in pelvic limb position, sweating in analgesic zones, urination, behavior, response to noise, and compliance with restraint were determined. Two-way ANOVA with repeated measures and Dunnett's t-tests were used to evaluate differences between the listed numerical scores, and cardiovascular and respiratory variables before and during a 5-hour testing period.

RESULTS

Subarachnoidally administered ropivacaine-induced variable analgesia extending bilaterally from the coccyx to S1, with minimal sedation and change in pelvic limb position in standing mares. Perineal analgesia was attained at 7.5 +/- 2.6 minutes and lasted for 218 +/- 44 minutes (mean +/- SD). Subarachnoid ropivacaine significantly reduced respiratory rates and did not change heart rate, rectal temperature, arterial blood pressure, PCV, arterial gas tensions (PaO2 and PaCO2), pH, and arterial standard bicarbonate and base excess from baseline.

CONCLUSION AND CLINICAL RELEVANCE

Ropivacaine (0.2% solution, 5 mL 500 kg(-1)) can be administered subarachnoidally at midsacral (S2-S3) vertebrae to produce prolonged (>3 hours) bilateral perineal analgesia with minimal changes of behavior, and circulatory and respiratory disturbances in standing mares.

Low-dose bupivacaine plus fentanyl for spinal anesthesia during ambulatory inguinal herniorrhaphy: a comparison between 6 mg and 7. 5 mg of bupivacaine

BACKGROUND

Inguinal herniorrhaphy is commonly performed as an outpatient procedure. Spinal anesthesia offers some advantages over general anesthesia in this setting.

METHODS

Forty patients were randomly divided into two groups according to a double-blind protocol: Group L had spinal anesthesia with bupivacaine 6.0 mg and Group H with bupivacaine 7.5 mg; in both groups, fentanyl 25 micro g was added to the spinal anesthetic. The sensory block was measured by 'pin-prick' and the motor block was evaluated by a modified Bromage scale.

RESULTS

No differences were seen in the spread, duration and regression of sensory block between the groups on the operated side. A greater number of patients required analgesics during the operation in Group L (6) compared with Group H (1) (P<0.05). The return of the modified Bromage scale to grade 0 was earlier in Group L than in Group H (P<0.05) but the time to mobilization and discharge was similar. Seven patients (17%) needed to be catheterized and two had the catheter retained overnight. Times to home discharge (median) were 350 and 445 min, respectively, in Groups L and H. Postoperatively and during the first week, visual analog pain scores, analgesic requirements and side-effects were similar between the groups. In Group H, 95% of the patients and in Group L 85% would have the same anesthetic again if operated upon for a similar procedure.

CONCLUSIONS

Spinal anesthesia with bupivacaine 7.5 mg and fentanyl offers an alternative to general or local anesthesia for ambulatory inguinal herniorrhaphy. However, the long discharge times and risk for urinary retention restrict its routine use in all patients.

Transient lumbar pain after 5% hyperbaric lignocaine spinal anaesthesia in patients having minor vascular surgery

Transient lumbar pain has been reported to occur frequently in patients having surgery using 5% hyperbaric lignocaine for spinal anaesthesia. The incidence of transient lumbar pain is highest with this agent in patients having surgery in the lithotomy position and in outpatients. The aim of this audit was to determine the incidence of transient lumbar pain in patients having minor surgery for the complications of peripheral vascular disease, a group of patients in whom short duration spinal anaesthesia is desirable. One hundred patients were audited prospectively. All patients had 5% hyperbaric lignocaine spinal anaesthesia and were followed up postoperatively utilizing a standardized questionnaire to determine the incidence of transient lumbar pain. The condition was found to occur in 4% of patients. This low incidence of transient lumbar pain justifies the continued use of 5% hyperbaric lignocaine for spinal anaesthesia in this group of patients.

Spinal anaesthesia: local anaesthetics and adjuncts in the ambulatory setting

Intrathecal lidocaine remains a popular choice for ambulatory spinal anaesthesia due to its reliability, rapid onset and predictable rapid recovery profile. However, concerns with transient neurological symptoms (TNS) and their significant association with lidocaine have generated interest in alternative local anaesthetic agents to provide adequate spinal anaesthesia with the briefest possible recovery period. This chapter updates current data on drug dose-response relationships for local anaesthetics and the increasing use of intrathecal adjuncts to improve the anaesthetic and recovery profile for ambulatory spinal anaesthesia. Newer spinal anaesthetic techniques for common ambulatory procedures highlight the success of combining subclinical doses of local anaesthetics and intrathecal adjuncts. Controversies regarding the possible lower risk of TNS with newer spinal anaesthetic techniques and new discharge criteria are reviewed. The final section provides technical pearls to optimize ambulatory spinal anaesthetic outcomes.