Local Lidocaine Research Articles

Destabilization of Phase-separated Structures in Local Anesthetic-containing Model Biomembranes

Abstract We observed the phase behaviors, and the changes of membrane fluidity in lipid membranes containing local anesthetics (LAs), lidocaine and tetracaine. The phase separation in DOPC/DPPC binary membranes had not been changed significantly by addition of LAs, whereas that in DOPC/DPPC/Chol ternary membranes was suppressed by LAs. In order to evaluate the membrane fluidity, Laurdan generalized polarization values of membranes were measured. The fluidity of DOPC-rich phase in the ternary membrane became lower as LAs concentration had increased. Our results indicated the correlation between physical property change on membrane and pharmacological functions of LAs.

Markedly lowering the viscosity of aqueous solutions of DNA by additives

Aqueous solutions of DNAs, while relevant in drug delivery and as a target of therapies, are often very viscous making them difficult to use. Since less viscous solutions could enable targeted drug delivery and/or therapies, the purpose of the present work was to explore compounds capable of “thinning” such DNA solutions under pharmaceutically relevant conditions. To this end, viscosities of aqueous solutions of DNAs and model polyanions were examined at 25°C in the absence and presence of a number of bulky organic salts (and related compounds) previously found to substantially lower the viscosities of concentrated protein solutions. Out of two dozen compounds tested, only three were found to be effective; the FDA-approved local anesthetics lidocaine, mepivacaine, and prilocaine at near-isotonic concentrations and pH 6.4 lowered solution viscosity of three different DNAs up to about 20 fold. The observed multi-fold viscosity reductions appear to be due to these bulky organic salts’ structure-specific non-covalent binding to nucleotide bases resulting in denaturation (unwinding) to, and stabilization of, single-stranded DNA.

Local Administration of Methylcobalamin and Lidocaine for Acute Ophthalmic Herpetic Neuralgia: A Single-Center Randomized Controlled Trial.

To determine the therapeutic efficacy of combined methylcobalamin and lidocaine for acute ophthalmic herpetic neuralgia (AOHN). Based on the onset, patients with AOHN (n=98) were randomly allocated into groups A (≤3days) and B (4 to 7days) and then subdivided into control (A0, B0; received intramuscular methylcobalamin in addition to local lidocaine injection) and treatment (A1, B1; received local injection of the methylcobalamin and lidocaine combination for 14days) groups. Treatment efficacy was assessed based on rash healing time, alteration of pain intensity, and interference with quality of life. Multilevel modeling and survival analysis were performed. The time (hours) to start and full opening of the affected eye and the time (hours) to start and full crusting were significantly reduced in both treatment groups (P<0.05 vs. controls). The mean pain scores in A1 (2.6±0.7) and B1 (1.2±0.8) decreased significantly compared with those in A0 (7.0±1.7) and B0 (5.6±1.9), and the difference between the two therapeutic strategies significantly increased over time. The median minimum intervention time was 6days in B1 and 11days in A1. The incidence of postherpetic neuralgia (PHN) was 2.04% at 3months. Methylcobalamin combined with lidocaine mediated detumescence and improved cutaneous healing of the affected area, as well as a significant and sustained analgesic effect on AOHN. The incidence of PHN was also significantly decreased. Local methylcobalamin intervention within 4 to 7days of onset may be an effective therapeutic option for AOHN.

Enhancement of the 1-Octanol/Water Partition Coefficient of the Anti-Inflammatory Indomethacin in the Presence of Lidocaine and Other Local Anesthetics.

Side effects and excessive potentiation of drug efficacy caused by polypharmacy are becoming important social issues. The apparent partition coefficient of indomethacin (log P'IND) increases in the presence of lidocaine, and this is used as a physicochemical model for investigating polypharmacy. We examined the changes in log P'IND caused by clinically used local anesthetics-lidocaine, tetracaine, mepivacaine, bupivacaine, and dibucaine-and by structurally similar basic drugs-procainamide, imipramine, and diltiazem. The quantitative structure-activity relationship study of log P'IND showed that the partition coefficient values (log PLA) and the structural entropic terms (ΔSobs, log f) of the additives affect log P'IND. These results indicate that the local anesthetics and structurally similar drugs function as phase-transfer catalysts, increasing the membrane permeability of indomethacin via heterogeneous intermolecular association. Therefore, we expect that the potency of indomethacin, an acidic nonsteroidal anti-inflammatory drug, will be increased by concurrent administration of the other drugs.

Evaluation of postmortem drug concentrations in cerebrospinal fluid compared with blood and pericardial fluid

In forensic toxicology, body fluids are important materials not only as alternatives to blood but also for investigation of postmortem drug redistributions and pharmaco-/toxicokinetic analysis; however, there are limited data on postmortem drug distributions in cerebrospinal fluid (CSF). The present study reviewed toxicological data of autopsy cases (n=103), in which drugs were detected in CSF using gas chromatography/mass spectrometry (GC/MS), to investigate drug concentrations in CSF, compared with blood and pericardial fluid (PCF) concentrations. Oral/injected amphetamines (n=23) showed similar CSF and blood/PCF concentrations with partly lower CSF concentrations (about ×0.5–1.1). CSF concentrations of the venous anesthetic midazolam (n=7) were lower with poor correlations. Oral caffeine (n=15), acetaminophen (n=7), chlorpheniramine (n=6), dihydrocodeine (n=6), and phenobarbital (n=21) showed equivalent to lower CSF concentrations (about ×0.2–1.2), compared with blood and PCF concentrations; however, CSF phenobarbital concentrations were high in a fatal intoxication case. CSF concentrations of phenothiazine derivatives (n=29) were markedly lower (about ×0.1) than blood/PCF concentrations. The distribution of the local anesthetic lidocaine used in critical medical care (n=49) markedly varied by case. These findings suggest that CSF is useful in routine forensic toxicology as an alternative to blood as well as for investigating pharmaco-/toxicokinetics and postmortem redistributions.

The molecular structure and vibrational, 1H and 13C NMR spectra of lidocaine hydrochloride monohydrate

The structure, vibrational and NMR spectra of the local anesthetic drug lidocaine hydrochloride monohydrate salt were investigated by B3LYP/6-311G∗∗ calculations. The lidocaine·HCl·H2O salt is predicted to have the gauche structure as the predominant form at ambient temperature with NCCN and CNCC torsional angles of 110° and −123° as compared to 10° and −64°, respectively in the base lidocaine. The repulsive interaction between the two N–H bonds destabilized the gauche structure of lidocaine·HCl·H2O salt. The analysis of the observed vibrational spectra is consistent with the presence of the lidocaine salt in only one gauche conformation at room temperature. The 1H and 13C NMR spectra of lidocaine·HCl·H2O were interpreted by experimental and DFT calculated chemical shifts of the lidocaine salt. The RMSD between experimental and theoretical 1H and 13C chemical shifts for lidocaine·HCl·H2O is 2.32 and 8.21ppm, respectively.

Rapid Vortex Fluidics: Continuous Flow Synthesis of Amides and Local Anesthetic Lidocaine.

Thin film flow chemistry using a vortex fluidic device (VFD) is effective in the scalable acylation of amines under shear, with the yields of the amides dramatically enhanced relative to traditional batch techniques. The optimized monophasic flow conditions are effective in ≤80 seconds at room temperature, enabling access to structurally diverse amides, functionalized amino acids and substituted ureas on multigram scales. Amide synthesis under flow was also extended to a total synthesis of local anesthetic lidocaine, with sequential reactions carried out in two serially linked VFD units. The synthesis could also be executed in a single VFD, in which the tandem reactions involve reagent delivery at different positions along the rapidly rotating tube with in situ solvent replacement, as a molecular assembly line process. This further highlights the versatility of the VFD in organic synthesis, as does the finding of a remarkably efficient debenzylation of p-methoxybenzyl amines.

Biocompatible lidocaine and prilocaine loaded-nanoemulsion system for enhanced percutaneous absorption: QbD-based optimisation, dermatokinetics and in vivo evaluation

Barrier properties of the skin and physicochemical properties of the drugs are the main hiccups in delivering local anaesthetic molecules topically. The present work endeavours for systematic optimisation and evaluation of nanoemulsions (NEs) of local anaesthetic drugs, lidocaine and prilocaine, employing the systematic approach of Quality by Design. A 33 Box–Behnken design was employed for systematic optimisation of the factors obtained from screening studies employing Plackett–Burman design and risk assessment studies. The superior permeation rates, and higher concentrations of the drugs in skin layers from the optimised NE carriers, were achieved in permeation and dermatokinetic studies, when compared to marketed cream. Furthermore, rapid onset of action was demonstrated by the NE system in rabbit eye corneal reflex model and biocompatibility was confirmed from the absence of any marked skin change(s) in the normal skin histology. The developed NE systems demonstrated it as a promising carrier for topical delivery of lidocaine and prilocaine.

Differential analgesic effects of subanesthetic concentrations of lidocaine on spontaneous and evoked pain in human painful neuroma: A randomized, double blind study

BackgroundBoth peripheral nerve injury and neuroma pain are the result of changes in sodium channel expression. Lidocaine selectively inhibits the spontaneous ectopic activity by binding to sodium channels. Subanesthetics concentrations of lidocaine are able to produce a differential block of the ectopic discharges, but not propagation of impulses, suppressing differentially the associated neuropathic pain symptoms. The aim of this study was to investigate the differences between the analgesic effects of lidocaine 0.5% and a control group of lidocaine 0.1% on several neuroma related pain modalities. MethodsSixteen patients with neuropathic pain due to painful neuromas caused by nerve injury participated in this randomized, double-blind experiment. The patterns of sensory changes were compared before and after injection of 1ml lidocaine 0.5% and 0.1% close to the neuroma, the sessions being 1–2 weeks apart. Spontaneous and evoked pains were assessed using a visual analogue scale (VAS), quantitative and qualitative sensory testing. The primary end-point measure was defined as the change in pain score measured from baseline until 60min after injection. Assessments of spontaneous pain and evoked pain were done post injection at 15s, 30s, 1min, and at 5-min intervals for the first 30-min post injection and then every 10-min to 1 hr post injection. The assessments of pain were performed between the limbs in the following order: spontaneous pain, then assessment of dynamic mechanical allodynia and then hyperalgesia. ResultsLidocaine dose-dependently reduced spontaneous and evoked pain scores by more than 80% with maximum effects between 1 and 5min for evoked pain and between 3 and 15min for spontaneous pain. While evoked pain normalized rapidly reaching about 50% of the control level 20min after the injection, spontaneous pain levels continue to be lower in comparison with baseline values for more than 60min. When comparing the time course of analgesia between spontaneous and evoked pain, lidocaine-induced a greater reduction of evoked pain, but with shorter duration than spontaneous pain. The differences between evoked pain and spontaneous pain were statistically significant in both groups (lidocaine 0.5% group; p=0.02 and lidocaine 0.1% group; p=0.01). Reproducibility was high for all assessed variables. Surprisingly, both lidocaine concentrations produced a sensory loss within the area with hyperalgesia and allodynia: hypoesthesia occurred earlier and lasted longer with lidocaine 0.5% (between 30s and 5min) in comparison with lidocaine 0.1% (p=0.018). ConclusionDifferential analgesic effects of subanesthetic concentrations of local lidocaine on evoked and spontaneous pain in human neuroma suggest that different mechanisms underlie these two key clinical symptoms. Spontaneous pain and evoked pain need an ongoing peripheral drive and any possible CNS amplification change is temporally closely related to this peripheral input. ImplicationsPainful neuroma represents a clinical model of peripheral neuropathic pain that could lead to a significant step forward in the understanding of pain pathophysiology providing the opportunity to study spontaneous and evoked pain and the underlying mechanisms of neuropathic pain. The proposed model of neuropathic pain allows testing new substances by administration of analgesics directly where the pain is generated.

Non-intubated anesthesia in thoracic surgery-technical issues.

Performing awake thoracic surgery (ATS) is technically more challenging than thoracic surgery under general anesthesia (GA), but it can result in a greater benefit for the patient. Local wound infiltration and lidocaine administration in the pleural space can be considered for ATS. More invasive techniques are local wound infiltration with wound catheter insertion, thoracic wall blocks, selective intercostal nerve blockade, thoracic paravertebral blockade and thoracic epidural analgesia, offering the advantage of a catheter placement which can also be continued for postoperative analgesia.

Diagnostic accuracy of sentinel node identification is maintained with the addition of local lidocaine and subareolar radioactive colloid injection.

Preoperative sentinel node localization (SNL) using a subareolar injection of radiotracer technetium-99m-sulfur colloid (Tc(99m)SC) is associated with significant pain. Lidocaine use during SNL is not widely adopted partly due to a concern that it can obscure sentinel node identification and reduce its diagnostic accuracy. We prospectively identified women with a biopsy-proven infiltrating breast cancer who were awaiting a SNL. The women completed the McGill pain questionnaire, Visual Analog Scale, and Wong-Baker FACES Pain Rating Scale prior to and following SNL. We identified a retrospective cohort of women with similar demographic and tumor characteristics who did not receive lidocaine before SNL. We compared sentinel lymph node identification rates in the two cohorts. We used Wilcoxon rank sum tests to compare continuous measures and Fisher's exact test for categorical measures. Between January 2011 to July 2012, 110 women consented, and 105 were eligible for and received lidocaine prior to Tc(99m)SC injection. The post-lidocaine identification rate of SNL was 95 % with Tc(99m)SC, and 100 % with the addition of intraoperative methylene blue dye/saline. Pain range prior to and following the SNL was unchanged (P = 0.703). We identified 187 women from 2005 to 2009 who did not receive lidocaine during preoperative SNL. There was no significant difference in the success rate of SNL, with or without lidocaine (P = 0.194). The administration of lidocaine during SNL prevents pain related to isotope injection while maintaining the success rate. We have changed our practice at our center to incorporate the use of lidocaine during all SNL.

The conformational stability, solvation and the assignments of the experimental infrared, Raman, 1H and 13C NMR spectra of the local anesthetic drug lidocaine

The structure, vibrational and 1H and 13C NMR spectra of the local anesthetic drug lidocaine were investigated by the B3LYP/6-311G∗∗ calculations. The molecule was predicted to have the non-planar cis (NCCN∼0°) structures being about 2–6kcal/mol lower in energy than the corresponding trans (NCCN∼180°) forms. The calculated NCCN (9.6°) and CNCC (−132.2°) torsional angles were in a good qualitative agreement with the reported X-ray angles (3.1 and 13.0°, −102.67 and −77.9°, respectively, for H-bonded dimers). The Gibbs energy of solution of lidocaine in formamide, water, dimethylsulfoxide, acetonitrile, methanol, ethanol and chloroform solutions was estimated at the B3LYP level. The predicted affinity of lidocaine toward the alcohols, acetonitrile and chloroform solutions was in excellent agreement with the reported experimental solubility of the drug in organic solvents. The analysis of the observed vibrational spectra is consistent with the presence of lidocaine in only one conformation at room temperature. The 1H and 13C NMR spectra of lidocaine were interpreted by experimental and DFT calculated chemical shifts of the drug. The RMSD between experimental and theoretical 1H and 13C chemical shifts for lidocaine is 0.47 and 8.26ppm, respectively.

Investigations into distribution of lidocaine in human autopsy material.

With screening methods in the legal medicine drugs were often detected in autopsy material. In this study the antiarrhythmic and the local anesthetic drug lidocaine could be proved in fifty-one cases and determined in different autopsy materials. For the first time the comparison of so many distribution patterns of lidocaine in human compartments was possible. A liquid-liquid extraction procedure, a standard addition method and LC/MS/MS were used for analytics. The measured concentrations in blood were in the therapeutic range or lower. The time between lidocaine application and death was given in twenty-nine cases. These data were very helpful to estimate and interpret the distribution process of lidocaine between application and death. This time exerted a crucial influence on the distribution of lidocaine in the compartments. Most of the intravenous applicated lidocaine was found in heart blood after a very short time of distribution. Afterwards the highest concentrations were measured in brain. Later the highest concentration was found in the kidney samples or in urine. If the time between lidocaine application and death is known, the results of this study can be used to deepen the knowledge of its pharmacokinetics. If this time is unknown, the circumstances and the causes of death can be better explained.

A Randomized, Double-Blind Controlled Trial of Lumbar Interlaminar Epidural Injections in Central Spinal Stenosis: 2-Year Follow-Up

Background: While low back pain is the number one cause of disability in the United States, lumbar spinal stenosis along with intervertebral disc herniation and degenerative spondylolisthesis is one of the 3 most common diagnosis of low back and leg pain for which surgery is performed. Numerous modalities of treatments including drug therapy and complex surgical fusions have been recommended for treatment of central spinal stenosis. Epidural injections are one of the commonly performed nonsurgical interventions in managing central spinal stenosis; however, there has been paucity of literature in reference to efficacy of epidural injections in managing central spinal stenosis with lumbar interlaminar epidural injections. Study Design: A randomized, double-blind, active controlled trial. Setting: Private interventional pain management practice and specialty referral center in the United States. Objective: To assess the effectiveness of lumbar interlaminar epidural injections with or without steroids in providing effective and long-lasting pain relief with improvement in functional status for the management of chronic low back and lower extremity pain related to lumbar central spinal stenosis. Methods: A randomized, double-blind, active-control trial was designed with the inclusion of 120 patients assigned to 2 groups. Group I patients received lumbar interlaminar epidural injections of local anesthetic (lidocaine 0.5%) 6 mL, whereas Group II received lumbar interlaminar epidural injections with local anesthetic (lidocaine 0.5%) 5 mL mixed with 1 mL of steroids and 6 mg of betamethasone. Outcomes Assessment: Outcomes were assessed utilizing the numeric pain rating scale (NRS) and Oswestry Disability Index (ODI) at 3, 6, 12, 18, and 24 months post treatment. The primary outcome measure was significant improvement, defined as 50% improvement in pain and disability scores. Results: Significant relief and functional status improvement was seen in 72% and 73% of patients in Groups I and II at the end of 2 years considering all participants; however, this was 84% and 85% in the successful group. Overall significant improvement was achieved for 65.7 ± 37.3 weeks in Group 1 and 68.9 ± 37.7 weeks in Group II at the end of 2 years when all participants were considered; whereas, this was 77 ± 27.8 weeks and 77.9 ± 30.2 weeks when they were separated into successful categories. The average number of procedures per patient was 5 to 6 in both groups. Limitations: Limitations of this trial include lack of placebo control group and treatment of patients with multiple procedures over a period of 2 years. Conclusion: Lumbar interlaminar epidural injections of local anesthetic with or without steroids provide relief in a significant proportion of patients with lumbar central spinal stenosis. Key words: Chronic low back pain, lower extremity pain, central spinal stenosis, interlaminar epidural injections, caudal epidural injections, steroids, local anesthetics, placebo, active control

Dexamethasone added to local lidocaine for infiltration along the spinal-epidural needle pathway decreases incidence and severity of backache after gynecological surgery.

BackgroundThe aim of this study was to evaluate the effect of dexamethasone added to local lidocaine infiltration on incidence and severity of backache after combined spinal-epidural anesthesia for gynecological surgery.Material/MethodsWe randomly allocated 160 patients to receive either local lidocaine infiltration along the pathway of the spinal-epidural needle (Group L) or local dexamethasone and lidocaine infiltration (Group DL). The incidence and scores for back pain were evaluated on the first, second, and third day (acute lumbago) and first, second, and sixth month (chronic lumbago) after surgery. Fentanyl consumption for management of back pain was recorded.ResultsThe incidence of acute, subacute, and chronic back pain was significantly lower in the DL group than the L group (P<0.05 for all comparisons). The VAS score for back pain on the first and second day and first and second month, were significantly lower in the DL group than the L group (P=0.0028, P=0.017; P<0.001, both), but there were no significant differences on the third day and sixth month. Fentanyl consumption in the first 3 postoperative days was significantly lower in the DL group than in the L group (P<0.001). The incidence of back pain during the first, second, and sixth month in patients who did not have preoperative lumbago were significantly lower in the DL group than in the L group (P<0.001, both).ConclusionsAddition of dexamethasone to local lidocaine infiltration effectively decreases the incidence and severity of back pain after combined spinal-epidural anesthesia implemented for gynecological surgery.

A comparative evaluation of 4% articaine and 2% lidocaine in mandibular buccal infiltration anesthesia: A clinical study.

Background:To compare 4% articaine and 2% lidocaine local anesthetics in achieving pulpal anesthesia of the lower first permanent molar teeth objectively, and to assess and compare lip and lingual mucosa numbness subjectively.Materials and Methods:All subjects received 1.7 ml of any one anesthetic in the mucobuccal fold adjacent to mandibular first molar teeth; the same individuals received the second infiltration at least 1 week after the first. Later, comparisons for pulpal anesthesia, lip and lingual mucosa numbness between these two anesthetics solutions were made.Results:Articaine showed significant results with P = 0.006 in achieving pulpal anesthesia objectively, when compared with lidocaine. Articaine also showed very high significant results subjectively with P = 0.0006 in achieving lip numbness, when compared with lidocaine. But the results in achieving lingual mucosa numbness with articaine subjectively was not significant with P = 0.01, when compared with lidocaine.Conclusion:Endodontic and operative treatments are one of the most common oral non-surgical procedures done under local anesthesia. The diversity of anesthetic substances currently available on the market requires dental professionals to assess the drug both by its pharmacokinetic and also by its clinical characteristics during dental treatments. Our study used 4% articaine, which is available in the market, for comparison with 2% lidocaine. Further studies are required to use an equal concentration of solutions to achieve more accurate results.

Effects of adding local anesthetic and iodinated contrast agents to the paramagnetic contrast solution in direct MR arthrography.

published in the present issue of Radiologia Brasi-leira. Such authors have carried out in vitro investigations of dif-ferent concentrations of diluted gadolinium-saline solution com-bined with local anesthetic (lidocaine) and iodinated contrast agent.The results of this study have potential implications for the evalu-ation of internal joint derangements using magnetic resonance ar-thrography (MRA).Iodinated contrast agent is included by some radiologists inthe composition of paramagnetic contrast-saline solution preparedfor direct MRA. Other radiologists prefer to inject iodinated con-trast into the joint prior the gadolinium injection. In both situa-tions, the iodinated contrast agent is useful to confirm the intra-articular positioning of the needle in cases where fluoroscopy isutilized to guide the procedure. With both techniques, the end resultis a mix of iodinated contrast agent and gadolinium in the intra-articular saline solution. Another advantage of using an end solu-tion with iodinated contrast agent is the possibility of converting aMRA into a computed tomography arthrography (CTA), in caseswhere the patient shows claustrophobia or in case of unexpectedtechnical problems with the MRI equipment during MRI acquisi-tion. CTA represents an interesting alternative to investigate jointdiseases when multislice CT equipment is available

Clonidine intensifies memantine cutaneous analgesia in response to local skin noxious pinprick in the rat

BackgroundThe purposes of this study were to evaluate the co-administration of clonidine with memantine and to determine whether it has a peripheral action in intensifying cutaneous analgesia. MethodsCutaneous analgesia was examined through inhibition of the cutaneous trunci muscle reflex in response to the local noxious pinprick in rats. Effect of the added subcutaneous clonidine to memantine on infiltrative cutaneous analgesia was assessed and compared with the local anesthetic lidocaine. ResultsOn the 50% effective dose (ED50) basis, the rank of drug potency was memantine [4.05 (3.95–4.18)μmol]>lidocaine [5.81 (5.70–5.98)μmol] (p<0.01). Clonidine at a dose of 0.12μmol did not elicit cutaneous analgesia. Mixtures of clonidine (0.12μmol) with drug (memantine or lidocaine) at ED50 or ED95 prolonged the duration of action and enhanced the potency as infiltrative cutaneous analgesia. Clonidine enhanced the lidocaine cutaneous analgesia in which had a better effect than added to memantine. ConclusionsOur resulting data showed that memantine displayed more potent cutaneous analgesia than lidocaine. Co-administration of memantine or lidocaine with clonidine increased the potency and duration of the cutaneous analgesia. Clonidine intensified the effects of lidocaine promoting cutaneous analgesia than added to memantine.

Treating Piriformis Syndrome with Sono-Guided Corticosteroid Local Injection: A Single-Center Experience

Objective: The current treatment strategy for piriformis syndrome includes rehabilitation, symptomatic relief and local injection with either corticosteroid or botulinum toxin. Blind injection is sometimes used, as are CT-guided or electromyography-guided injection techniques. We report our local experience in treating piriformis syndrome with sono-guided corticosteroid injection. Methods: We enrolled 29 patients with piriformis syndrome whose initial symptoms were not relieved after medical treatment. They then received sono-guided local corticosteroid and lidocaine injection. Instead of traditional localization using anatomical landmarks, we used ultrasound to directly visualize the piriformis muscle and perform sono-guided local injection. The outcome was measured using a Likert pain scale. The pre-treatment pain score was recorded for every patient. During the six-month follow-up, the minimal pain score achieved was recorded for each patient as the post-treatment pain score. The Wilcoxon rank sum test was used to evaluate the difference between pre-treatment and post-treatment Likert pain scales. Results: Of the 29 patients with piriformis syndrome, 12 were male (41.4%), and 17 were female (58.6%). The ages of the patients ranged from 22 to 89 years, and the mean age was 59.1. The average pre-treatment and post-treatment pain scores were 7.7 ± 1.7 and 1 ± 2.8, respectively, which showed a statistically significant improvement (p＜0.001). In all, 65.5% of the patients had more than 50% reduction of pain. None of the 29 patients had complications after the treatment.Conclusion: Local corticosteroid injection guided by ultrasound is a safe and effective treatment modality for piriformis syndrome.

Use of lidocaine in endotracheal intubation. Blood and urine concentrations in patients and deceased after unsuccessful resuscitation

In toxicological analysis of postmortem samples the local anesthetic lidocaine is often identified. In most cases, lidocaine levels result from its use as aid in endotracheal intubation. The range of the drug's concentration in blood and urine was studied under controlled conditions from a cohort of cardiac surgery patients (n=35).Plasma concentrations 1h after exposure to lidocaine in the range of the recommended 81mg coating the endotracheal tube were less than 0.2mg/l, its metabolite monoethylglycinxylidide (MEGX) less than 0.05mg/l (median ratio 0.18, range 0.03–1.23). Also the concentrations of lidocaine and MEGX in urine samples were low (less than 1.2 and 0.1mg/l, respectively) with MEGX/lidocaine ratios of 0.11 (median, range up to 1.2). These data were compared with results obtained by analyzing postmortem blood and urine samples of 18 deceased with a documented cardiopulmonary resuscitation attempt prior to death. Blood concentrations were in the same range (lidocaine median 0.07, range 0.02–1.07mg/l; MEGX median 0.01, range <0.001–0.044mg/l); besides low lidocaine concentrations in urine. MEGX was detected only in 2 out of 9 urine samples.The results of the present study confirm that lidocaine is absorbed in the trachea from the endotracheal tube coated with lidocaine containing gel. Postmortem quantitative results can be explained on the basis of the data obtained in the controlled study.