Local Anesthetic Side Effects Research Articles

The role of adjuvants in regional anesthesia: the postoperative analgesic effectiveness of dexamethasone vs. tramadol given as adjuvants to bupivacaine for ultrasound-guided supraclavicular block for upper extremity surgery—a prospective cohort study

BackgroundBrachial plexus block is used as a surgical anesthesia and analgesia for postoperative pain. Recently, the use of local anesthetics for regional nerve block has been enhanced by mixing them with a different class of drugs as adjuvants. These adjuvants of local anesthetics improved the quality and duration of nerve block and reduced the dose-dependent side effects of local anesthetics. However, the effectiveness of these adjuvants varies depending on the nature of the nerve block and the type of local anesthetics used. Therefore, we aimed to compare the postoperative analgesic effectiveness of dexamethasone vs. tramadol when used as adjuvants to bupivacaine for ultrasound-guided supraclavicular block in upper extremity surgery.MethodsUtilizing a prospective cohort study design, 126 consecutive patients who were undergoing upper extremity surgery with ultrasound-guided supraclavicular block were included. Patients were divided into three groups based on the preference of the responsible anesthetist to use adjuvants with bupivacaine for the block. The dexamethasone group (n = 42) were given 30 ml of 0.25% bupivacaine with 8 mg dexamethasone, the tramadol group (n = 42) were given 30 ml of 0.25% bupivacaine with 100 mg tramadol, and the non-adjuvant group (n = 42) were given 30 ml of 0.25% bupivacaine alone. The primary outcomes evaluated were postoperative pain severity using the numerical pain rating scale (NRS), the duration of analgesia, and the total postoperative analgesic consumption. Secondary outcomes included the incidence of postoperative complications.ResultA total of 126 patients were recruited and analyzed. There was no statistical difference in the demographic data among the groups. The postoperative NRS score was significantly reduced in the dexamethasone and tramadol group compared with the non-adjuvant group (p < 0.001). The NRS score in the dexamethasone group at 18 and 24 h was statistically much lower than in the tramadol and non-adjuvant group. The postoperative duration of analgesia was significantly prolonged in the dexamethasone (1,069 ± 316.99 min) group compared with the tramadol (617.02 ± 214.05 min) and non-adjuvant (434.17 ± 111.23 min) groups (p < 0.001). Patients in the non-adjuvant group had a significantly higher total analgesic consumption over 24 h. The dexamethasone group experienced significantly fewer incidences of nausea, with no differences in other complications among the groups.ConclusionThe addition of dexamethasone as an adjuvant to bupivacaine for ultrasound-guided supraclavicular block improves postoperative analgesia. We recommend the integration of dexamethasone as an adjuvant to local anesthetics during nerve blocks to enhance postoperative pain management after surgery.

Development of a Dosage form for a Photoswitchable Local Anesthetic Ethercaine.

The toxicity of local anesthetics is a serious problem, given their widespread use. One of the main causes of the side effects of local anesthetics is their non-selectivity of action in the body. A possible way to increase the selectivity of the action of drugs is to use the photopharmacology approach. Previously, we described the light-controlled local anesthetic ethercaine, the biological effect of which can be controlled using light, thereby increasing its selectivity of action. An important limitation of ethercaine was its low solubility in water, limiting the potential of this compound. In this work, we developed a dosage form of ethercaine, which allowed us to increase its solubility from 0.6% to 2% or more. The resulting 1% solution of ethercaine hydrochloride in 4% Kolliphor ELP had high biological activity on the surface anesthesia model, while demonstrating low acute toxicity in mice with intravenous administration (4-5 times less than that of lidocaine).

Serious Side Effects of Local Anesthetics’s Absorption in Blood Stream

Local anesthesia is widely performed in healthcare field and requires attentiveness. It is noted that the absorption of local anesthetics into the bloodstream could provoke vital organ affection. Central nervous system toxicity and cardiovascular toxicity are common high risk effects with crucial consequences. Additionally, local and generalized side effects such as allergy, kidney and liver failure are also potential incidents. Cautious performance, professional training and ability for prompt intervention are considered important and pivotal in local anesthetics administration.

Labour analgesia-epidural/combined spinal epidural/dural puncture epidural/entonox - A cafeteria choice for the patient or just research!

Labour analgesia-epidural/combined spinal epidural/dural puncture epidural/entonox - A cafeteria choice for the patient or just research!

Нежелательные реакции местных анестетиков

The article explains the adverse reactions of local anesthetics, in particular one of them, called the toxicity of local anesthetics. It has been shown that for the development of systemic toxicity of local anesthetics, higher doses of the latter are required in comparison with those recommended in the instructions. It is proposed in the regulatory documents to replace the term 'toxicity of local anesthetics' with the term 'side effects of local anesthetics'

MicroRNA-183-5p protects human derived cell line SH-SY5Y cells from mepivacaine-induced injury

ABSTRACT With the gradual recognition of the side effects of local anesthetics, the nerve injury caused by local anesthetics has received growing attention. This research intended to delve into miR-183-5p changes in mepivacaine-mediated SH-SY5Y cell injury, as well as its modulatory mechanism on cell apoptosis. RT-qPCR was adopted for assaying miR-183-5p and PDCD4 mRNA expression. Our team respectively transfected miR-183-5p mimic and inhibitor to enhance or inhibit miR-183-5p function. We employed Western blot for detecting PDCD4 protein levels, as well as flow cytometry and Hoechst 33342/PI double staining for determining cell apoptosis rate. Additionally, our crew applied an ELISA kit for measuring TNF-α, IL-1β, IL-6, and IL-8 contents. The level of reactive oxygen species (ROS) production was examined by the Image-iT LIVE Green ROS detection Kit. As well as dual-luciferase reporter experiment for verifying the targeting link of miR-183-5p with PDCD4. In mepivacaine-induced cell apoptosis in SH-SY5Y cells, miR-183-5p expression was down-regulated. TNF-α, IL-1β, IL-6, and IL-8 contents were elevated. The rate of apoptosis increased visibly, cleaved caspase-3 and Bax levels waxed, whereas Bcl-2 level waned. MiR-183-5p could alleviate the damaging impact of mepivacaine. Dual-luciferase reporter experiments demonstrated that miR-183-5p directly targeted PDCD4. Collectively, we concluded that a high concentration of mepivacaine can cause SH-SY5Y cell damage, miR-183-5p functions crucially in mepivacaine-mediated cell damage. This study provides a theoretical basis for elucidating the mechanism of mepivacaine-induced nerve cell damage, and overexpressed miR-183-5p likely become a novel strategy to combat mepivacaine-induced nerve damage. Abbreviations: miRNA: Micro RNA; PDCD4: Programmed Cell Death 4; MDA: Malondialdehyde; SOD: Superoxide Dismutase; ROS: Reactive Oxygen Species; WT: Wild Type; Mut: Mutant; UTR: Untranslated Region; IL-6: Interleukin-6; IL-1β: Interleukin-1β; TNF-α: Tumor Necrosis Factor-α; IL-8: Interleukin-8; COX-2: Cyclooxygenase-2; iNOS: inducible NOS; MEP: Mepivacaine

The analgesic efficacy of the continuous adductor canal block compared to continuous intravenous fentanyl infusion with a single-shot adductor canal block in total knee arthroplasty: a randomized controlled trial.

BackgroundThe adductor canal block (ACB) is an effective intervention for postoperative analgesia following total knee arthroplasty (TKA). However, the ideal ACB regimen has not yet been established. We compared the analgesic effects between a continuous ACB group and fentanyl-based intravenous patient-controlled analgesia (IV-PCA) with a single-shot ACB group.MethodsPatients who underwent TKA were randomly allocated to either a continuous ACB group (Group CACB) or IV-PCA with a single-shot ACB group (Group IVACB). Before the surgery, ultrasound guided ACB with 0.5% ropivacaine 20 cc was provided to all patients. Before skin incision, the infusion system (0.2% ropivacaine through an adductor canal catheter in group CACB vs. intravenous fentanyl in group IVACB) was connected. The postoperative pain severity; the side effects of local anesthetics and opioids; administration of rescue analgesics and anti-emetics; and sensorimotor deficits were measured.ResultsPostoperative pain severity was significantly higher in the IVACB group at 30 min, 4 h, 24 h, and 48 h after surgery. The averages and standard deviations (SD) of the NRS score of postoperative pain were 0.14 ± 0.37, 4.57 ± 2.37, 6.00 ± 1.63, and 4.28 ± 1.49, respectively in the IVACB group. Rescue analgesic requirements and quadriceps muscle strength were not statistically different between the groups throughout the postoperative period. Moreover, rescue antiemetic requirements were higher in group IVACB than group CACB.ConclusionsIn this study, the continuous ACB provided superior analgesia and fewer side effects without any significant motor deficit than the IV-PCA with a single-shot ACB.

Future Local Anesthetics – Neurotoxins?

The currently available local anaesthetics are non-specific blockers of the voltage gated sodium channels. Neurotoxins, derived from various sources are very potent and specific sodium channel blockers. Their site is also quite different from local anaesthetics. Their major toxic manifestation is muscle paralysis, which is easier to manage as compared to the serious cardiac and neurological side effects of local anaesthetics. These properties make neurotoxins almost an ideal local anaesthetic. A brief mention of the currently available neurotoxins and early studies with them are summarized.

High-Volume Infiltration Analgesia in Major Lumbar Spine Surgery. A Randomized, Placebo-Controlled, Double-Blind Trial

Background: High-volume local infiltration analgesia is effective in knee arthroplasty, but the analgesic efficacy of systematic infiltration with high-volume local anesthetic in major lumbar spine surgery in L3 to S1 has not been clarified. We conducted a trial to evaluate the analgesic efficacy of intraoperative Local Infiltration Analgesia (LIA) administration and postoperatively via injections through intraoperatively placed wound catheters. Methods: In a randomized, double-blind, placebo-controlled trial in 48 patients undergoing major lumbar spine fusion surgery, 70 mL saline (n=24) or ropivacaine 0.5% with adrenaline (n=24) was infiltrated using a systematic technique to all tissue incised, handled or instrumented during surgery and with repeated injections at 6, 12 and 24 h postoperatively with 10, 10 and 20 mL. Twenty-two patients in each group were used for analysis. Allocation was determined by using a computer generated random sequence concealed in consecutively numbered sealed envelopes, which were opened on the morning of surgery. For postoperative analgesia 2 multi-hole catheters were placed under the fascia of the m. erector spinae and subcutaneously in accordance with the randomization. The primary end-point was postoperative pain at rest, during leg elevation and walking for 48 hours postoperatively. Secondary end-point was the amount of administered opioid in the same period. Results: VAS pain scores were only significantly lower at 3 hours postoperatively in the ropivacaine group with straight leg elevation (p=0.0169) and at 7 hours in the ropivacaine group during walking (p=0.0133). At 25 hours postoperatively, there was a slightly significant reduction in pain scores from repeated injection of ropivacaine vs. saline in the catheters both during elevated straight leg test (p=0.0495) and during walking (p=0.0192). Rescue opioid requirements (24 h) were about 30 % lower in the ropivacaine group (p<0.05). No local anesthetic side effects were observed. Conclusion: Intraoperative high-volume wound infiltration with ropivacaine in major lumbar spine fusion surgery may only have a small analgesic effect in early postoperative pain management and after local anesthetic administration through multiholed wound catheters 24 hours postoperatively.

Lumbar plexus block as a method of postoperative analgesia after hip surgery

BackgroundPosterior lumbar plexus block provides unilateral blockade and great hemodynamic stability. In this trial, the efficacy of addition of clonidine to bupivacaine used in lumbar plexus block (LPB) was evaluated.Patients and methodsSixty ASA I or II adult patients undergoing hip surgery, receiving general anesthesia, were randomly allocated to three equal sized groups, according to the technique of postoperative analgesia. In group A patients extubated when they met the standard extubation criteria. In group B, a mixed solution of 15 mL bupivacaine 0.5% and 15 mL normal saline 0.9% was injected through lumbar plexus block technique before extubation. In group C, 2.5 μg/ml clonidine was added to bupivacaine. Postoperative pain, sedation, hemodynamics, analgesic consumption, local anesthetic side effects and serum cortisol level were compared.ResultsThere was a highly significant statistical difference between the three groups as regards the postoperative VAS scores (P < 0.001). In contrast to group A patients, VAS remained <50 mm till the 6th hour postoperatively in group B patients and till the 12th hour in group C with high significant difference in postoperative morphine consumption (P < 0.001). Hemodynamics and respiratory rate were in normal range 2 h postoperatively in the three groups. After the 6th hour postoperatively; SBP, DBP, HR and RR were significantly higher in group A patients in comparison to groups B and C (P < 0.05). In group C patients; SBP, DBP, HR and RR were in normal range for the first 12 h postoperatively. Blood cortisol level was higher then normal in group A patients since 2 h postoperatively (P, 0.05), while started to rise from the 6th hour in group B patients and the 12th hour in group C patients.ConclusionThe study showed that posterior lumbar plexus block was an effective postoperative analgesic technique in patients undergoing hip surgeries and that adding clonidine in a concentration of 2.5 μg/ml to bupivacaine 0.25% has resulted in decreasing the postoperative analgesic requirements.

Tricyclic antidepressants: old drugs-new applications.

Dear Editor, With great interest I have read an excellent article “Evaluation of the efficacy of intrathecal injection of amitriptyline and doxepin in spinal anesthesia in comparison with bupivacaine in rats“, published in your respected journal. The authors present and elaborate a very interesting subject of the application of tricyclic antidepressants as a local anesthetic. I totally agree with the authors of article that claim that there is a tendency of intrathecal injection of various drugs with different effect mechanisms (1). Several papers in the recent years, including the already mentioned article, indicate the local anesthetic effect of tricyclic antidepressants. In doing so, they demonstrate the effect of the drug on motor, sensory and proprioceptive fibers (2, 3). I think it would be very interesting to, by studying the above- mentioned block modes, to consider the possible effect of tricyclic antidepressants on the block of the vegetative (sympathetic) fibers and the possible hemodynamic changes that can occur. It is well known that in spinal anesthesia with conventional anesthetics, due to sympathetic blockade, very dramatic hemodynamic changes can arise, and that may be the cause of morbidity and mortality. The article states that in group of tested animal to which amitriptyline were injected three rats died. The discussion states that the possible cause of death is heart failure due to the toxic effect of high-dosed amitriptyline. Unfortunately, drugs concentration in plasma in dead animals is unknown, as it was not the subject of the research. Is it possible that the amitriptyline cause extensive sympathetic block, which leads to a drastic reduction in cardiac output and peripheral vascular resistance and consequent cardiovascular failure in animals, rather than direct toxic effect? Also, in future, if intention for studies in humans is planned, it should examine the neurotoxic potential of tricyclic antidepressants, especially in the intrathecal injection. For example, ten years ago, Gernes have presented a derivative of lidocaine, named tonicaine, with very strong local anesthetic properties. Block with tonicaine was four to nine times longer than with lidocaine; tonicaine had 80 times higher potential in blocking the Na+ currents than lidocaine, and possesed significantly better sensorimotoric discrimination than lidocaine. Unfortunately, due to evidence of neutotoxicity at lower concentrations, the researchers determined that the tested substance may have only limited clinical value (4). In general, today's research into new intrathecal agents that could be used in spinal anesthesia and analgesia occurs in two directions: one is research of already well-defined substances for a new type of application-as intrathecal anesthetic or as an adjuvant (e. g. tricyclic antidepressants, midazolam, ά 2-agonists); the other direction is the exploration of entirely new substances. In this endeavor, a new synthetic peptide specifically for intrathecal use, ziconotide, has been introduced into clinical practice (USA 2004, EU 2005). It is intended for treatment of severe chronic pain who do not respond to or cannot tolerate opioid therapy (5). The devolopment of the new anesthetic agents continues because it is relatively easy to synthetize substances with local anesthetic properties. Unfortunately, it is difficult to reduce the toxicity of these compounds because the most common side effects of local anesthetics present an extension of their therapeutic properties. New research on mechanisms of cardiac and spinal toxicity induced by the local anesthetic and identification of new drug target for spinal analgesia suggests the possible development of new (or old one for new type of application) and safer anesthetic in the future.

High-Dose Bupivacaine Remotely Loaded into Multivesicular Liposomes Demonstrates Slow Drug Release Without Systemic Toxic Plasma Concentrations After Subcutaneous Administration in Humans

Depot formulations prolong the analgesic effect of local anesthetics and reduce peak plasma drug concentration. This allows for safer administration of larger doses of local anesthetics, which further prolongs the duration of analgesic effect. We previously reported the development of large multivesicular vesicles (LMVVs) remotely loaded with bupivacaine (LMVV liposomal bupivacaine) and demonstrated a >5-fold prolongation of analgesic effect in animals and humans. In this study, we present pharmacokinetic data of LMVV liposomal bupivacaine in humans. Healthy volunteers received subcutaneous injections of 20 mL plain 0.5% bupivacaine and, 1 week later, 20 mL of 2% LMVV liposomal bupivacaine in a prospective, open-label, crossover, controlled study. Eight subjects were studied. No subjective side effects of local anesthetics were observed. The maximal plasma concentration and the time to achieve maximal plasma concentration were assessed by modeling plasma concentration-time profiles. Maximal plasma concentration was not significantly different between groups (0.87 +/- 0.45 microg/mL and 0.83 +/- 0.34 microg/mL for plain and liposomal bupivacaine, respectively; P = not significant, 0.83). These values are well below the putative toxic plasma concentration of 2 to 4 microg/mL. Time to achieve maximal plasma concentration was 7-fold greater for the liposomal preparation (262 +/- 149 minutes vs 37.5 +/- 16 minutes, P < 0.01). Peak plasma bupivacaine concentrations were not different in the 2 groups, despite a 4-fold increase in total bupivacaine dose administered in the novel liposomal preparation. The delayed elimination and prolonged redistribution of liposomal bupivacaine to plasma is compatible with the depot-related slow-release effect leading to the prolonged pharmacodynamic effect previously reported.

Excretion of Ropivacaine in Breast Milk During Patient-controlled Epidural Analgesia After Cesarean Delivery

Background Few studies have been published concerning the excretion of bupivacaine and lidocaine into the breast milk and none concerning ropivacaine. Aim The aim of this study was to determine the levels of ropivacaine in plasma and breast milk after combined spinal-epidural anesthesia for cesarean delivery and postoperative patient-controlled epidural analgesia (PCEA), as well as possible adverse effects from these levels on the neonate. Methods Twenty-five parturients admitted for cesarean delivery under combined spinal-epidural anesthesia participated in the study. The PCEA regimen was prepared as 0.15% ropivacaine and fentanyl 2 microg/mL (basal rate, 6 mL/h; demand dose, 4 mL/20 min). Blood samples were collected before anesthesia and from the umbilical cord immediately after birth, followed by blood and breast milk samples 18 and 24 hrs after initiation of PCEA. The newborns were clinically appraised with the Apgar score at delivery and Neurological and Adaptive Capacity Score 24 hrs later. Local anesthetic side effects were recorded. Ropivacaine levels were determined by high-performance liquid chromatography with a UV detector. Results Ropivacaine excretion into the breast milk produced concentrations that significantly correlated with those in the plasma 18 and 24 hrs after administration, achieving milk-plasma ratios (mean +/- SD) of 0.25 +/- 0.08 and 0.23 +/- 0.07, respectively. Most newborns had maximal Apgar and Neurological and Adaptive Capacity Scores. No adverse effects from ropivacaine were noted in mothers or neonates. Conclusions The milk-plasma concentration ratio of ropivacaine was found to be lower than that reported for other local anesthetics It seems that PCEA with ropivacaine/fentanyl after cesarean delivery is not associated with excessive milk-plasma concentrations of ropivacaine.

Recovery from long-lasting post-tonsillectomy dysgeusia

Transient post-tonsillectomy taste dysgeusia (PTD) is a common complaint. Long-lasting PTD is less frequent but has significant consequences on patients' quality of life, with some cases leading to medicolegal issues. Treatment options and knowledge about mechanisms and factors favoring PTD are limited. PTD may result from direct surgical injury, tongue compression, inflammatory processes or side effects of local anesthetics. Some authors also claim that dietary zinc deficiency plays a role in the development of PTD. Although this latter cause had not yet received a lot of attention, we report a case of a female patient who reported a 4-year PTD and recovered within 2 months after oral intake of zinc sulfate. This clinical observation, together with recent findings on significant improvement of taste disorders after zinc treatments for other causes, opens again the question of what extent zinc deficiency plays a role in PTD.

Excretion of Ropivacaine in Breast Milk During Patient-Controlled Epidural Analgesia After Cesarean Delivery

Few studies have been published concerning the excretion of bupivacaine and lidocaine into the breast milk and none concerning ropivacaine. The aim of this study was to determine the levels of ropivacaine in plasma and breast milk after combined spinal-epidural anesthesia for cesarean delivery and postoperative patient-controlled epidural analgesia (PCEA), as well as possible adverse effects from these levels on the neonate. Twenty-five parturients admitted for cesarean delivery under combined spinal-epidural anesthesia participated in the study. The PCEA regimen was prepared as 0.15% ropivacaine and fentanyl 2 microg/mL (basal rate, 6 mL/h; demand dose, 4 mL/20 min). Blood samples were collected before anesthesia and from the umbilical cord immediately after birth, followed by blood and breast milk samples 18 and 24 hrs after initiation of PCEA. The newborns were clinically appraised with the Apgar score at delivery and Neurological and Adaptive Capacity Score 24 hrs later. Local anesthetic side effects were recorded. Ropivacaine levels were determined by high-performance liquid chromatography with a UV detector. Ropivacaine excretion into the breast milk produced concentrations that significantly correlated with those in the plasma 18 and 24 hrs after administration, achieving milk-plasma ratios (mean +/- SD) of 0.25 +/- 0.08 and 0.23 +/- 0.07, respectively. Most newborns had maximal Apgar and Neurological and Adaptive Capacity Scores. No adverse effects from ropivacaine were noted in mothers or neonates. The milk-plasma concentration ratio of ropivacaine was found to be lower than that reported for other local anesthetics It seems that PCEA with ropivacaine/fentanyl after cesarean delivery is not associated with excessive milk-plasma concentrations of ropivacaine.

Intrathecal and Epidural Anesthesia and Analgesia for Cardiac Surgery

Adequate postoperative analgesia prevents unnecessary patient discomfort. It may also decrease morbidity, postoperative hospital length of stay and, thus, cost. Achieving optimal pain relief after cardiac surgery is often difficult. Many techniques are available, and all have specific advantages and disadvantages. Intrathecal and epidural techniques clearly produce reliable analgesia in patients undergoing cardiac surgery. Additional potential benefits include stress response attenuation and thoracic cardiac sympathectomy. The quality of analgesia obtained with thoracic epidural anesthetic techniques is sufficient to allow cardiac surgery to be performed in awake patients without general endotracheal anesthesia. However, applying regional anesthetic techniques to patients undergoing cardiac surgery is not without risk. Side effects of local anesthetics (hypotension) and opioids (pruritus, nausea/vomiting, urinary retention, and respiratory depression), when used in this manner, may complicate perioperative management. Increased risk of hematoma formation in this scenario has generated much of lively debate regarding the acceptable risk-benefit ratio of applying regional anesthetic techniques to patients undergoing cardiac surgery.

Analgesia after arthroscopic rotator cuff repair: Subacromial versus interscalene continuous infusion of ropivacaine

A continuous infusion of local anesthetic in the subacromial space has been shown to provide superior pain relief compared with placebo. This technique has been considered as an alternative to a continuous interscalene infusion. The aim of our study is to compare these 2 techniques for pain relief after arthroscopic rotator cuff repair. In a prospective randomized trial, 30 consecutive patients undergoing rotator cuff repair were included. An interscalene brachial plexus block was performed in all patients with mepivacaine 1.5% 30 mL. Then, 15 patients had an indwelling interscalene catheter inserted immediately after the block via a needle. Fifteen other patients had a subacromial catheter placed at the end of surgery by the surgeon. In both groups, a 2 mg/mL ropivacaine continuous infusion (5 mL/h) with PCA bolus (5 mL/30 min) was maintained for 48 hours. Pain was assessed in PACU and at 24 and 48 hours after surgery, at rest, and during passive motion. Total amount of oral morphine self-administered as rescue analgesia and cumulative 24-hour and 48-hour local anesthetic consumption were noted. Patient satisfaction and side effects were also noted. Pain during motion in PACU (0 [0 to 60] v 40 [0 to 100] mm) and at 24 hours (10 [0 to 60] v 45 [20 to 100] mm), oral morphine (0 [0 to 6] v 3.5 [0 to 10] morphine capsules), and total amount of local anesthetic at 24 hours (122.5 [120 to 170] v 143 [129 to 250] mg) were lower in the continuous interscalene group. Local anesthetic side effects were less frequent in the continuous subacromial group. Satisfaction was comparable between groups. After arthroscopic rotator cuff repair, continuous interscalene block provides better analgesia compared with continuous subacromial infusion but with an increased incidence of minor side effects.

Anesthesia for dermatological surgery

Knowledge of local anesthesia is critically important to perform dermatological surgery. Local anesthetics when used judiciously are extremely safe and allow dermatologists to perform a variety of procedures. This article aims to provide an updated review of local anesthesia and local anesthetic drugs. Side effects of local anesthetics and techniques of regional anesthesia are discussed and some commonly used nerve blocks are explained. A detailed knowledge of the pharmacology of local anesthetics aids in optimal therapeutic use, and in prevention, early diagnosis and management of their toxicities by the clinician.

Forearm rescue cuff improves tourniquet tolerance during intravenous regional anesthesia

Background and Objectives: Tourniquet pain during intravenous regional anesthesia (IVRA) of the upper limb is common and can limit tourniquet inflation time. We hypothesize that a forearm rescue cuff is better tolerated than the traditional rescue cuff of a double-cuff tourniquet. Methods: After Institutional Review Board (IRB) approval and informed consent, 10 healthy unmedicated volunteers took part in a prospective, randomized, cross-over study. Following inflation of the proximal tourniquet cuff on the upper arm, a standardized IVRA with 0.5% lidocaine, 0.6 mL/kg was administered. When the volunteer complained of tourniquet pain, or at 30 minutes, the initial cuff was changed to a rescue cuff. During session A, the rescue cuff was the traditional distal cuff of the double-cuff tourniquet. During session B, a single forearm cuff was used. When the volunteer experienced the same level of tourniquet pain, the rescue cuff was deflated and the study session ended. The tourniquet time for the rescue cuff, the visual analog scale (VAS) pain score, and the incidence and duration of side effects were recorded. Results: The forearm rescue cuff was tolerated significantly longer than the arm rescue cuff (49 ± 15 v 29 ± 11 minutes, 95% confidence interval [CI] 7 to 32 minutes, P ≤ .005). When the forearm rescue cuff was used, VAS scores were lower and side effects were of shorter duration (6 ± 5 v 15 ± 7 minutes, P < .001). Conclusions: A forearm rescue cuff is better tolerated than an arm cuff double tourniquet during IVRA, allowing for longer tourniquet times. It is also associated with lower pain scores and shorter duration of local anesthetic side effects. Reg Anesth Pain Med 2003;28:98-102.

Anxiety, vocalization, and agitation following peripheral nerve block with ropivacaine

Background and Objectives. Central nervous system (CNS) and cardiovascular toxicity are potential side effects of local anesthetics. However, ropivacaine has been reported to be less CNS toxic than bupivacaine in human volunteers. Methods. We describe three cases of peripheral nerve blockade with ropivacaine that resulted in unusual symptoms of CNS toxicity. Results. In three patients, unexpected behavioral changes occurred during administration of ropivacaine. The patients became extremely agitated, anxious, and screamed, and they did not repsond to verbal commands. Conclusion: This case report shows that ropivacaine may cause CNS toxicity that differs from classical signs of local anesthetic-induced toxicity. This effect might be related to the unique structure of ropivacaine, which is formulated in an S-enantomer preparation. It has been shown that S-enantomers bind differently to receptors in both the CNS and cardiovascular systems. This property may account for the disinhibition of select neural pathways that are specifically involved in mediation of anxiety and aggression.