General anesthetic agents induce neurotoxicity through oligodendrocytes in the developing brain

General anesthetic agents can impact brain function through interactions with neurons and their effects on glial cells.Oligodendrocytes perform essential roles in the central nervous system,including myelin sheath formation,axonal metabolism,and neuroplasticity regulation.They are particularly vulnerable to the effects of general anesthetic agents resulting in impaired proliferation,differentiation,and apoptosis.Neurologists are increasingly interested in the effects of general anesthetic agents on oligodendrocytes.These agents not only act on the surface receptors of oligodendrocytes to elicit neuroinflammation through modulation of signaling pathways,but also disrupt metabolic processes and alter the expression of genes involved in oligodendrocyte development and function.In this review,we summarize the effects of general anesthetic agents on oligodendrocytes.We anticipate that future research will continue to explore these effects and develop strategies to decrease the incidence of adverse reactions associated with the use of general anesthetic agents.

General anesthetic agents induce neurotoxicity through astrocytes

Neuroscientists have recognized the importance of astrocytes in regulating neurological function and their influence on the release of glial transmitters.Few studies,however,have focused on the effects of general anesthetic agents on neuroglia or astrocytes.Astrocytes can also be an important target of general anesthetic agents as they exert not only sedative,analgesic,and amnesic effects but also mediate general anesthetic-induced neurotoxicity and postoperative cognitive dysfunction.Here,we analyzed recent advances in understanding the mechanism of general anesthetic agents on astrocytes,and found that exposure to general anesthetic agents will destroy the morphology and proliferation of astrocytes,in addition to acting on the receptors on their surface,which not only affect Ca^(2+)signaling,inhibit the release of brain-derived neurotrophic factor and lactate from astrocytes,but are even involved in the regulation of the pro-and anti-inflammatory processes of astrocytes.These would obviously affect the communication between astrocytes as well as between astrocytes and neighboring neurons,other neuroglia,and vascular cells.In this review,we summarize how general anesthetic agents act on neurons via astrocytes,and explore potential mechanisms of action of general anesthetic agents on the nervous system.We hope that this review will provide a new direction for mitigating the neurotoxicity of general anesthetic agents.

Anesthesia,Anesthetics,and Postoperative Cognitive Dysfunction in Elderly Patients

Postoperative cognitive dysfunction(POCD)remains a major issue that worsens the prognosis of elderly surgery patients.This article reviews the current research on the effect of different anesthesia methods and commonly utilized anesthetics on the incidence of POCD in elderly patients,aiming to provide an understanding of the underlying mechanisms contributing to this condition and facilitate the development of more reasonable anesthesia protocols,ultimately reducing the incidence of POCD in elderly surgery patients.

Inhaled volatile anesthetics in the intensive care unit

The discovery and utilization of volatile anesthetics has significantly transformed surgical practices since their inception in the mid-19th century.Recently,a paradigm shift is observed as volatile anesthetics extend beyond traditional confines of the operating theatres,finding diverse applications in intensive care settings.In the dynamic landscape of intensive care,volatile anesthetics emerge as a promising avenue for addressing complex sedation requirements,managing refractory lung pathologies including acute respiratory distress syndrome and status asthmaticus,conditions of high sedative requirements including burns,high opioid or alcohol use and neurological conditions such as status epilepticus.Volatile anesthetics can be administered through either inhaled route via anesthetic machines/devices or through extracorporeal membrane oxygenation circuitry,providing intensivists with multiple options to tailor therapy.Furthermore,their unique pharmacokinetic profiles render them titratable and empower clinicians to individualize management with heightened accuracy,mitigating risks associated with conventional sedation modalities.Despite the amounting enthusiasm for the use of these therapies,barriers to widespread utilization include expanding equipment availability,staff familiarity and training of safe use.This article delves into the realm of applying inhaled volatile anesthetics in the intensive care unit through discussing their pharmacology,administration considerations in intensive care settings,complication considerations,and listing indications and evidence of the use of volatile anesthetics in the critically ill patient population.

Studies on Anesthetic Effect of Eugenol on Juvenile Fenneropenaeus chinensis

[Objective] The aim of the study is to seek a good anesthetic to Fenneropenaeus chinensis. [Method] The anesthetic effect of eugenol to juvenile Fenneropenaeus chinensis was investigated. [Result] The juveniles could be effectively anaesthetized by 50-400 mg/L eugenol aqueous solution with temperature of 24 ℃. Within the concentration range of 50-400 mg/L, the increase of the eugenol concentration could shorten the time required for anesthesia, meanwhile could prolong the time for recovery. The recovered rate of prawn reached 100% when the eugenol concentration was lower than 200 mg/L, while the recovered rate of prawn was just 66.67% when the eugenol concentration was higher than 400 mg/L. The survival rate of prawns in test group was 100% from the observation of three consecutive days. For the specific dose, the anesthetic effect enhanced with the increase of water temperature (18-27℃). [Conclusion] Eugenol is a safe and efficient anesthetics that can be applied in genetic breeding of prawn.

Effect of intraperitoneal local anesthetic on pain characteristics after laparoscopic cholecystectomy

AIM : To systematically evaluate the effect of intraperitoneal local anesthetic on pain characteristics after laparoscopic cholecystectomy(LC).METHODS: We searched MEDLINE, EMBASE, and the Cochrane Library. Randomized controlled trials in English that compared the effect of intraperitoneal administration of local anesthetics on pain with that of placebo or nothing after elective LC under general anesthesia were included. The primary outcome variables analyzed were the combined scores of abdominal, visceral, parietal, and shoulder pain after LC at multiple time points. We also extracted pain scores at resting and dynamic states.RESULTS: We included 39 studies of 3045 patients in total. The administration of intraperitoneal local anesthetic reduced pain intensity in a resting state after laparoscopic cholecystectomy: abdominal [standardized mean difference(SMD) =-0.741; 95%CI:-1.001 to-0.48, P < 0.001]; visceral(SMD =-0.249; 95%CI:-0.493 to-0.006, P = 0.774); and shoulder(SMD =-0.273; 95%CI:-0.464 to-0.082, P = 0.097). Application of intraperitoneal local anesthetic significantly reduced the incidence of shoulder pain(RR = 0.437; 95%CI: 0.299 to 0.639, P < 0.001). There was no favorable effect on resting parietal or dynamic abdominal pain.CONCLUSION: Intraperitoneal local anesthetic as an analgesic adjuvant in patients undergoing laparoscopic cholecystectomy exhibited beneficial effects on postoperative abdominal, visceral, and shoulder pain in a resting state.

Anesthetic management for small bowel enteroscopy in a World Gastroenterology Organization Endoscopy Training Center

AIM:To study the anesthetic management of patients undergoing small bowel enteroscopy in the World Gastroenterology Organization(WGO) Endoscopy Training Center in Thailand.METHODS:Patients who underwent small bowel enteroscopy during the period of March 2005 to March 2011 in Siriraj Gastrointestinal Endoscopy Center were retrospectively analyzed.The patients' characteristics,pre-anesthetic problems,anesthetic techniques,anesthetic agents,anesthetic time,type and route of procedure and anesthesia-related complications were assessed.RESULTS:One hundred and forty-four patients underwent this procedure during the study period.The mean age of the patients was 57.6 ± 17.2 years,andmost were American Society of Anesthesiologists(ASA) class Ⅱ(53.2%).Indications for this procedure were gastrointestinal bleeding(59.7%),chronic diarrhea(14.3%),protein losing enteropathy(2.6%) and others(23.4%).Hematologic disease,hypertension,heart disease and electrolyte imbalance were the most common pre-anesthetic problems.General anesthesia with endotracheal tube was the anesthetic technique mainly employed(50.6%).The main anesthetic agents administered were fentanyl,propofol and midazolam.The mean anesthetic time was 94.0 ± 50.5 min.Single balloon and oral(antegrade) intubation was the most common type and route of enteroscopy.The anesthesia-related complication rate was relatively high.The overall and cardiovascular-related complication rates including hypotension in the older patient group(aged ≥ 60 years old) were significantly higher than those in the younger group.CONCLUSION:During anesthetic management for small bowel enteroscopy,special techniques and drugs are not routinely required.However,for safety reasons anesthetic personnel need to optimize the patient's condition.

Adjuvants to local anesthetics: Current understanding and future trends

Although beneficial in acute and chronic pain management, the use of local anaesthetics is limited by itsduration of action and the dose dependent adverse effects on the cardiac and central nervous system. Adjuvants or additives are often used with local anaesthetics for its synergistic effect by prolonging the duration of sensory-motor block and limiting the cumulative dose requirement of local anaesthetics. The armamentarium of local anesthetic adjuvants have evolved over time from classical opioids to a wide array of drugs spanning several groups and varying mechanisms of action. A large array of opioids ranging from morphine, fentanyl and sufentanyl to hydromorphone, buprenorphine and tramadol has been used with varying success. However, their use has been limited by their adverse effect like respiratory depression, nausea, vomiting and pruritus, especially with its neuraxial use. Epinephrine potentiates the local anesthetics by its antinociceptive properties mediated by alpha-2 adrenoreceptor activation along with its vasoconstrictive properties limiting the systemic absorption of local anesthetics. Alpha 2 adrenoreceptor antagonists like clonidine and dexmedetomidine are one of the most widely used class of local anesthetic adjuvants. Other drugs like steroids(dexamethasone), anti-inflammatory agents(parecoxib and lornoxicam), midazolam, ketamine, magnesium sulfate and neostigmine have also been used with mixed success. The concern regarding the safety profile of these adjuvants is due to its potential neurotoxicity and neurological complications which necessitate further research in this direction. Current research is directed towards a search for agents and techniques which would prolong local anaesthetic action without its deleterious effects. This includes novel approaches like use of charged molecules to produce local anaesthetic action(tonicaine and n butyl tetracaine), new age delivery mechanisms for prolonged bioavailability(liposomal, microspheres and cyclodextrin systems) and further studies with other drugs(adenosine, neuromuscular blockers, dextrans).

Laparoscopic cholecystectomy in patients with anesthetic problems

Laparoscopic cholecystectomy is a standard operation for benign gallbladder disease. As experience with laparoscopic cholecystectomy has increased, the procedure has become possible in patients with anesthetic problems. Patients with ankylosing spondylitis or severe kyphosis represent a challenging group to anesthesiologists and laparoscopic surgeons since these diseases are associated with difficult intubation, restrictive ventilatory defects, and cardiac problems. The relatively new approach of awake fiberoptic intubation is considered to be the safest option for patients with anticipated airway difficulties. Laparoscopic cholecystectomy is usually performed under general anesthesia but considerable difficulties in anesthetic management are encountered during laparoscopic surgery; for example, hemodynamic instability may develop in patients with cardiopulmonary dysfunction due to pneumoperitoneum and position changes during the operation. Nonetheless, regional anesthesia can be considered as a valid option for patients with gallbladder disease who are poor candidates for general anesthesia due to cardiopulmonary problems. We report three cases of laparoscopic cholecystectomy successfully performed in patients with anesthetic problems that included cardiopulmonary disease, severe kyphosis, and ankylosing spondylitis.

Anesthetic management and associated complications of peroral endoscopic myotomy:A case series

AIM To investigate the anesthetic management of peroral endoscopic myotomy(POEM) and its associated complications.METHODS This study was a single-center,retrospective,observational study comprising a case series of all patients who underwent POEM in our hospital from April 2015 to November 2016.We collected data regarding patient characteristics,anesthetic methods,surgical factors,and complications using an electronic chart.RESULTS There were 86 patients who underwent POEM in our hospital during the study period.Preoperatively,patients were maintained on a low residue diet for 48 h prior to the procedure.They were fasted of solids for 24 h before surgery.There was one case of aspiration(1.2%).During POEM,patients were positioned supine with the upper abdomen covered by a clear drape so that pneumoperitoneum could be timeously identified.In three cases,the peak airway pressure exceeded 35 cm H2 O during volume controlled ventilation with tidal volumes of 6-8 m L/kg and subsequent impairment of ventilation.These cases had been diagnosed with spastic esophageal disorders(SEDs) and the length of the muscular incision on the esophageal side was longer than normal.CONCLUSION In the anesthetic management of POEM,it is important to prevent aspiration during induction of anesthesia and to identify and treat complications associated with CO_2 insufflation.

Effect of Inhalational Anesthetics on Cytotoxicity and Intracellular Calcium Differently in Rat Pheochromocytoma Cells (PC12)

Isoflurane, a commonly used inhaled anesthetic, induces apoptosis in rat pheochromocytoma cells （PC12） in a concentration- and time-dependent manner with unknown mechanism. We hypothesized that isoflurane induced apoptosis by causing abnormal calcium release from the endoplasmic reticulum （ER） via activation of inositol 1,4,5-trisphosphate （IP3） receptors. Alzheimer＇s presenilin-1 （PS 1） mutation increased activity of IP3 receptors and therefore rendered cells vulnerable to isoflurane-induced cytotoxicity. Sevoflurane and desflurane had less ability to disrupt intracellular calcium homeostasis and thus being less potent pared the cytotoxic effects of various inhaled to cause cytotoxicity. This study examined and com-anesthetics on PC12 cells transfected with the Alzheimer＇s mutated PS 1 （L286V） and the disruption of intracellular calcium homeostasis. PC 12 cells transfected with wild type （WT） and mutated PS 1 （L286V） were treated with equivalent of 1 MAC of isoflurane, sevoflurane and desflurane for 12 h. MTT reduction and LDH release assays were performed to evaluate cell viability. Changes of calcium concentration in cytosolic space （[Ca^2＋]c） were determined after exposing different types of cells to various inhalational anesthetics. The effects of IP3 receptor antagonist xestospongin C on isoflurane-induced cytotoxicity and calcium release from the ER in L286V PC12 cells were also determined. The results showed that isoflurane at 1 MAC for 12 h induced cytoxicity in L286V but not WT PC12 cells, which was also associated with greater and faster elevation of peak [Ca^2＋]c in L286V than in the WT cells. Xestospongin C significantly ameliorated isoflurane cytotoxicity in L286V cells, as well as inhibited the calcium release from the ER in L286V cells. Sevoflurane and desflurane at equivalent exposure to isoflurane did not induce similar cytotoxicity or elevation of peak [Ca^2＋]c in L286V PC 12 cells. These results suggested that isoflurane induced cytoxicity by partially causing abnormal calcium release from the ER via activation of IP3 receptors in L286V PC12 cells. Sevoflurane and desflurane at equivalent exposure to isoflurane did not induce similar elevation of [Ca^2＋]c or neurotoxicity in PC 12 cells transfected with the Alzheimer＇s PS 1 mutation.

Delayed xenon post-conditioning mitigates spinal cord ischemia/reperfusion injury in rabbits by regulating microglial activation and inflammatory factors

The neuroprotective effect against spinal cord ischemia/reperfusion injury in rats exerted by delayed xenon post-conditioning is stronger than that produced by immediate xenon post-conditioning. However, the mechanisms underlying this process remain unclear. Activated microglia are the main inflammatory cell type in the nervous system. The release of pro-inflammatory factors following microglial activation can lead to spinal cord damage, and inhibition of microglial activation can relieve spinal cord ischemia/reperfusion injury. To investigate how xenon regulates microglial activation and the release of inflammatory factors, a rabbit model of spinal cord ischemia/reperfusion injury was induced by balloon occlusion of the infrarenal aorta. After establishment of the model, two interventions were given： （1） immediate xenon post-conditioning—after reperfusion, inhalation of 50% xenon for 1 hour, 50% N2/50%O2 for 2 hours; （2） delayed xenon post-conditioning—after reperfusion, inhalation of 50% N2/50%O2 for 2 hours, 50% xenon for 1 hour. At 4, 8, 24, 48 and 72 hours after reperfusion, hindlimb locomotor function was scored using the Jacobs locomotor scale. At 72 hours after reperfusion, interleukin 6 and interleukin 10 levels in the spinal cord of each group were measured using western blot assays. Iba1 levels were determined using immunohistochemistry and a western blot assay. The number of normal neurons at the injury site was quantified using hematoxylin-eosin staining. At 72 hours after reperfusion, delayed xenon post-conditioning remarkably enhanced hindlimb motor function, increased the number of normal neurons at the injury site, decreased Iba1 levels, and inhibited interleukin-6 and interleukin-10 levels in the spinal cord.Immediate xenon post-conditioning did not noticeably affect the above-mentioned indexes. These findings indicate that delayed xenon post-conditioning after spinal cord injury improves the recovery of neurological function by reducing microglial activation and the release of interleukin-6 and interleukin-10.

Exertional rhabdomyolysis and heat stroke: Beware of volatile anesthetic sedation

In view of the enormous popularity of mass sporting events such as half-marathons, the number of patients with exertional rhabdomyolysis or exercise-induced heat stroke admitted to intensive care units(ICUs) has increased over the last decade. Because these patients have been reported to be at risk for malignant hyperthermia during general anesthesia, the intensive care community should bear in mind that the same risk of life-threatening rhabdomyolysis is present when these patients are admitted to an ICU, and volatile anesthetic sedation is chosen as the sedative technique. As illustrated by the three case studies we elaborate upon, a thorough diagnostic work-up is needed to clarify the subsequent risk of strenuous exercise, and the anesthetic exposure to volatile agents in these patients and their families. Other contraindications for the use of volatile intensive care sedation consist of known malignant hyperthermia susceptibility, congenital myopathies, Duchenne muscular dystrophy, and intracranial hypertension.

Ischemic post-conditioning to counteract intestinal ischemia/reperfusion injury

Intestinal ischemia is a severe disorder with a variety of causes.Reperfusion is a common occurrence during treatment of acute intestinal ischemia but the injury resulting from ischemia/reperfusion(IR)may lead toeven more serious complications from intestinal atrophy to multiple organ failure and death.The susceptibility of the intestine to IR-induced injury(IRI)appears from various experimental studies and clinical settings such as cardiac and major vascular surgery and organ transplantation.Where as oxygen free radicals,activation of leukocytes,failure of microvascular perfusion,cellular acidosis and disturbance of intracellular homeo-stasis have been implicated as important factors inthe pathogenesis of intestinal IRI,the mechanisms underlying this disorder are not well known.To date,increasing attention is being paid in animal studies to potential pre-and post-ischemia treatments that protect against intestinal IRI such as drug interference with IR-induced apoptosis and inflammation processes and ischemic pre-conditioning.However,better insight is needed into the molecular and cellular events associated with reperfusion-induced damage to develop effective clinical protection protocols to combat this disorder.In this respect,the use of ischemic post-conditioning in combination with experimentally prolonged acidosis blocking deleterious reperfusion actions may turn out to have particular clinical relevance.

Acute lens opacity induced by different kinds of anesthetic drugs in mice

AIM: To study whether specific anesthetic drugs or tear layer evaporation was primarily responsible for the acute cataract and what the change of lens structure is in anesthetized mice.METHODS: Five groups were set up in the experiment: Group A(topicamide and phenylephrine mixed eye drop+ chloral hydrate), Group B(tropicamide and phenylephrine mixed eye drop+sevoflurane), Group C(tropicamide and phenylephrine mixed eye drop), Group D(topicamide and phenylephrine mixed eye drop+chloral hydrate, carbomer eye drop in the right eyes), and Group E(tropicamide and phenylephrine mixed eye drop+sevoflurane, carbomer eye drop in the right eyes). A simple classification system was used to assess the severity of lens opacity. And a numerical value from 0 to 3 to each grade was assigned for the cataract index calculation and data analysis. The gross appearance and time course of development of lens opacity were assessed. Hematoxylin and eosin staining was used to observe the lens structure changes in the reversible cataract.RESULTS: Tropicamide did not induce lens opacification in mice. Lens opacity caused by inhaled sevoflurane was similar to injected cholral hydrate. Both inhaled-anestheticinduced lens opacity and injected-anesthetic-induced lens opacity could be prevented by carbomer eye drop. In the severe opacity lens, a wide range of lens fiber cell structure had disordered. The fiber cells became uneven thickness.CONCLUSION: The acute reversible lens opacity can unilaterally develop or be induced by a local cause. The structure of lens fiber cells changed in the lens opacity which may influence the permanent connection of the lens fiber cells. This study was not only of practical significance to help maintain lens transparency for eye research, but also of the deeper consideration about the reversible lens opacification phenomenon.

Anesthetic Action of Volatile Anesthetics by Using Paramecium as a Model

Although empirically well understood in their clinical administration, volatile anesthetics are not yet well comprehended in their mechanism studies. A major conundrum emerging from these studies is that there is no validated model to assess the presumed candidate sites of the anesthetics. We undertook this study to test the hypothesis that the single-celled Paramecium could be anesthetized and served as a model organism in the study of anesthetics. We assessed the motion of Paramecium cells with Expert Vision system and the chemoresponse of Paramecium cells with T-maze assays in the presence of four different volatile anesthetics, including isoflurane, sevoflurane, enflurane and ether. Each of those volatiles was dissolved in buffers to give drug concentrations equal to 0.8, 1.0, and 1.2 EC50, respectively, in clinical practice. We could see that after application of volatile anesthetics, the swimming of the Paramecium cells was accelerated and then suppressed, or even stopped eventually, and the index of the chemoresponse of the Paramecium cells （denoted as Iche） was decreased. All of the above impacts were found in a concentration-dependent fashion. The biphasic effects of the clinical concentrations of volatile anesthetics on Paramecium simulated the situation of high species in anesthesia, and the inhibition of the chemoresponse also indicated anesthetized. In conclusion, the findings in our studies suggested that the single-celled Paramecium could be anesthetized with clinical concentrations of volatile anesthetics and therefore be utilized as a model organism to study the mechanisms of volatile anesthetics.

Protective effects of intravenous anesthetics on kidney tissue in obstructive jaundice

AIM: To evaluate the protective effects on kidney tissue of frequently used intravenous anesthetics (ketamine, propofol, thiopental, and fentanyl) in rats with obstructive jaundice.

Why Labor Epidural Causes Fever and Why Lidocaine Burns on Injection? Role of TRPV 1 Receptor in Hyperthermia: Possible Explanation of Mechanism of Hyperthermia during Labor Epidural and Burning Sensation on Injection of Local Anesthetics

The mechanisms of epidural-associated fever remain incompletely understood [1-3]. We propose that action of local anesthetic on TPRV1. The transient receptor potential cation channel subfamily V member 1 (TRPV1), also known as the capsaicin receptor and the vanilloid receptor can explain this effect and explain mechanism of burning sensation on local anesthetic injected subcutaneously or intramuscular. Role of TRPV1 receptor was not discussed previously in Obstetric Anesthesia literature. Based on available data, we propose that Local Anesthetics work as agonist/antagonist on TPRV1 receptors. Antagonist action may cause hyperthermia through modifying thermoregulation [4], agonist action may cause hyperthermia thru release of IL-6 and other mediators of inflammation [5-10]. Agonist action may explain burning sensation on injection of Local Anesthetics. Burning sensation can be diminished by increasing pH of Local Anesthetic solution, because vanillin receptors are stimulated by acidification through lower pH [11,12].

Is there any difference in anesthetic management of different post-OLT stage patients undergoing nontransplant organ surgery?

BACKGROUND: Little information is available about anesthesia management of nontransplant organ surgery of recipients after adult liver transplantation. The aim of this study was to discuss the anesthesia management of recipients for different stages after liver transplantation. METHODS: The medical records of 16 patients were reviewed after OLT scheduled for elective nontransplant organ surgery at our institution from September 2002 to October 2005. The patients were divided into perioperative stage (group A) and mid-term and long-term stage (group B) groups according to post-OLT time. The data of 16 patients preoperation, intraoperation and postoperation were analyzed. RESULTS: The measurements of alanine transaminase (ALT), total bilirubin (TB), prothrombin time (PT), and lung infection were significantly higher in group A than in group B (P<0.05). The incidence of hyperglycaemia was significantly higher in group B than in group A (P<0.05). During operation the incidence of hypotension was significantly higher in group A than in group B (P<0.05). After operation, the number of patients in ICU was significantly larger and the extubation time was longer in group A than in group B. General anesthesia was induced in 14 patients, and regional anesthesia in 2 patients. CONCLUSIONS: Regional or general anesthesia can be safely delivered to adult OLT recipients except for contraindications. Special considerations include protection of the function of important organs, correction of hemodynamic instability in perioperative stage patients after OLT, and measurement of the side-effects of immunosuppression in mid-term and long-term stage patients.

Features and Principles the Spread of Local Anesthetic Blockade of the Sciatic Nerve at Depends on the Amount of Anesthetic

Aim: To study the features of local anesthetic solution spreading during sciatic nerve block in dependence on the anesthetic solution volume. Material and Methods: One hundred and sixty nine cases of sciatic nerve blocks done under ultrasonic visualization control were analyzed. Sciatic nerve blocks were performed by lidocaine in volumes 30;25;20;15;12.5;10;7.5;6.5;5;4.5 ml. The cross-section area, equal to local anesthetic spreading, was determined;the extension of the anesthetic solution spreading along sciatic nerve was calculated. Results: The anesthetic agent solution spreads along sciatic nerve in proximal and distal direction, forming a kind of cylinder. The minimum volume of the local anesthetic, which covers sciatic nerve in the whole, is 5 ml. A rare (1.77%) variation of sciatic nerve structure was described, in which tibial and common peroneal nerves develop directly from the branches of sacral plexus. Conclusion: The decrease of the local anesthetic volume leads to reduction of its spreading distance and cross-section area. Ultrasonic visualization can provide for sciatic nerve anatomical peculiarities, which can have an effect on the block quality.