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.

Comparative studies on the binding site of anesthetics to GABA a receptors using in silico docking methods

Although the GABAA receptor(GABAAR)has been proposed as the main action site for sevoflurane,isoflurane,halothane,enflurane,propofol,and benzodiazepines(BZDs),binding of these anesthetics with high-resolution structures of the GABAAR have been rarely examined by comparative docking analyses.Moreover,various combinations of ligands on more GABAARs with various subtypes need to be analyzed to understand the elaborate action mechanism of GABAARs better because some GABAA ligands showed specificity toward the distinct subtypes of the GABAAR.Methods:We performed in silico docking analysis to compare the binding modes of sevoflurane,isoflurane,halothane,enflurane,propofol,and BZDs to the GABAAR based on one of the most recently provided 3D structures.We performed the docking analysis and the affinity-based ranking of the binding sites.Results:Our docking studies revealed that isoflurane,halothane,and enflurane docked in an extracellular domain(ECD)on GABAARs,in contrast to sevoflurane.Conclusion:Our results supported a multi-site mechanism for the allosteric modulation of propofol.Propofol was bound to the pore or favored various subsites in the transmembrane domain(TMD).Our result confirmed that different chemically related BZD ligands interact via distinct binding modes rather than by using a common binding mode,as previously suggested.

Anesthetic effect of phenobarbital sodium on female BALB/c mice

Objective:Anesthetics are of great importance in avoiding severe pain and suffering in animals and ensuring experimental progress.This study was aimed at elucidating the anesthesia score of phenobarbital sodium as a general anesthetic at different concentrations and doses in BALB/c mice,and finding the suitable anesthesia strategies for experimental surgeries.Methods:Phenobarbital sodium was administrated intraperitoneally at the doses of 75,100,125,150,and 200 mg/kg and randomly in different concentrations(2%,5%,and 10%)to female BALB/c mice.The anesthesia score was evaluated based on the stimulus index including tail-pinch,front and hind limb withdrawal,and eyelid reflexes.The speed and duration of anesthesia in different groups were recorded per the occurrence and duration of the righting reflex.Results:The anesthetic effect of phenobarbital sodium on female BALB/c mice showed an obvious dose-dependency.Respiratory suppression caused by high-dose anesthesia may lead to mouse death.Based on the anesthesia score,when the phenobarbital sodium treatment was greater than or equal to five percent or 200 mg/kg,more than 80%mice meet the anesthesia depth that surgical operation needed.The rates of achieving surgical anesthesia depth(standard-reaching rate)in mice treated with 2%sodium phenobarbital were 0%in the 75 mg/kg group,0%in the 100 mg/kg group,50%in the 125 mg/kg group,66.7%in the 150 mg/kg group,and 100%in the 200 mg/kg group.The standard-reaching rate of mice treated with 5%concentration of phenobarbital sodium were:0%in the 75 mg/kg group,0%in the 100 mg/kg group,83.33%in the 125 mg/kg group,100%in the 150 mg/kg group,and 100%in the 200 mg/kg group.The standard-reaching rate of mice treated with 10%concentration of phenobarbital sodium were:50%in the 75 mg/kg group,66.7%in the 100 mg/kg group,100%in the 125 mg/kg group,100%in the 150mg/kg group,and 100%in the 200 mg/kg group.Sedation and hypnosis were induced in the low-concentration dose group,and anesthesia was induced in the high-concentration dose group.In the 5%and 125 mg/kg phenobarbital sodium groups,the mortality rate of mice was 0,the anesthesia induction time was(35.5±7.92)minutes,and the anesthesia duration was(106±39.59)minutes.In the 5%and 150 mg/kg phenobarbital sodium groups,the mortality rate of mice was 0,the anesthesia induction time was(34.83±5.27)minutes,and the anesthesia duration was(131.7±36.75)minutes.Conclusion:Phenobarbital sodium alone can provide appropriate general anesthesia in female BALB/c mice.Both the concentration and dose of phenobarbital sodium can affect the anesthetic effect.On the basis of our findings,we recommend the 5%and 125 mg/kg and 5%and 150 mg/kg concentration–dose combinations of phenobarbital sodium for anesthetizing mice according to the surgical requirement.

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.

Neuroendocrine,epigenetic,and intergenerational effects of general anesthetics

The progress of modern medicine would be impossible without the use of general anesthetics(GAs).Despite advancements in refining anesthesia approaches,the effects of GAs are not fully reversible upon GA withdrawal.Neurocognitive deficiencies attributed to GA exposure may persist in neonates or endure for weeks to years in the elderly.Human studies on the mechanisms of the long-term adverse effects of GAs are needed to improve the safety of general anesthesia but they are hampered not only by ethical limitations specific to human research,but also by a lack of specific biological markers that can be used in human studies to safely and objectively study such effects.The latter can primarily be attributed to an insufficient understanding of the full range of the biological effects induced by GAs and the molecular mechanisms mediating such effects even in rodents,which are far more extensively studied than any other species.Our most recent experimental findings in rodents suggest that GAs may adversely affect many more people than is currently anticipated.Specifically,we have shown that anesthesia with the commonly used GA sevoflurane induces in exposed animals not only neuroendocrine abnormalities(somatic effects),but also epigenetic reprogramming of germ cells(germ cell effects).The latter may pass the neurobehavioral effects of parental sevoflurane exposure to the offspring,who may be affected even at levels of anesthesia that are not harmful to the exposed parents.The large number of patients who require general anesthesia,the even larger number of their future unexposed offspring whose health may be affected,and a growing number of neurodevelopmental disorders of unknown etiology underscore the translational importance of investigating the intergenerational effects of GAs.In this mini review,we discuss emerging experimental findings on neuroendocrine,epigenetic,and intergenerational effects of GAs.

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.

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.

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.

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].

Sugar Derivatives of Morphine:A New Window for the Development of Potent Anesthetic Drugs

This review provides a short account of carbohydrate derivatives of an important natural drug,morphine,along with their comparative efficacies as anesthetic agent.Sugar derivatives are found to have more prospect as anesthetic drug than morphine itself owing to their enhanced bioavailability.Synthetic schemes of these sugar derivatives and information on related patents are also included in this manuscript.

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.

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.

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.

Early and Late Postoperative Pain and Side Effects after Mastectomy: A Comparison of Ketamine and Thiamylal Administered for Anesthetic Induction

Objective: To compare acute and long-term postoperative pain and side effects in patients undergoing mastectomy for breast cancer under general anesthesia induced with ketamine or thiamylal. Methods: Twenty four ASA physical status I-III patients undergoing mastectomy were randomly assigned to one of two groups. Ketamine group received intravenous ketamine, 1 mg/kg, and thiamylal group received intravenous thiamylal, 4 mg/kg, at the induction of general anesthesia. Anesthesia was maintained with sevoflurane, N2O and fentanyl. The intensity of pain was assessed by using visual analog scale (VAS) 3 and 16 hr and 2, 3 and 4 weeks after surgery. Postoperative side effects, including nausea, vomiting and hallucination were also recorded. Results: At 16 hr after surgery, VAS in ketamine group was significantly lower than that in thiamylal group. However, there were no statistically significant differences between the two groups in the VAS at 3 hr and 2, 3 and 4 weeks after surgery. There were no differences in the incidence of side effects such as nausea, vomiting and hallucination between the two groups. Conclusion: Intravenous ketamine at the induction of anesthesia could reduce acute postoperative pain but not long-term pain after mastectomy.

Different Volumes of Local Anesthetics in Ultrasound-Guided Combined Interscalene-Supraclavicular Block for Traumatic Humeral Fracture

Background: Procedures that require anesthesia of entire length of the arm should have combined Interscalene block (ISB) and Supraclavicular block (SCB) to ensure adequate block. However, dual block requires high dose of local anesthetic (LA). We examined if Ultrasound (U/S) guided block helps to decrease the required volume of LA by visualizing trunks, so we only need injection of LA toward cervical nerve roots C5 and C6 aiming to block branches escaped from supraclavicular block. Patients and methods: Ninety-three patients were randomly allocated into one of three equal groups, each included 31 patients. All patients received SCB 20 ml (10 ml Bupivacaine 0.5% plus 10 ml lidocaine 2%) and ISB with different volumes of LA according to the group as follow: group A: 20 ml, group B: 15 ml, and group C: 10 ml. Result: No significant difference in onset of block (sensory and motor) and duration of block (motor only) between the three groups (P value > 0.05). The duration of sensory block was significantly longer in group A (760.65 ± 30.87 minutes) than in either group B (740.48 ± 21.15 minutes, P value P value P value P value P value P value < 0.001). Conclusion: A reduced volume of LA can be used in ultra sound guided ISB in combined with SCB to give satisfactory level of anesthesia to entire length of the arm, but the sensory block duration and duration of post-operative analgesia will be decreased significantly with decreasing the volume.

Neurophenotyping of Zebrafish Larvae that Are Preconditioned with Anesthetic Agent

Anesthetics evoke a stress-response, upregulating heat shock genes. This neuroprotective response to proteotoxic stress represents preconditioning, a process by which neuronal tissue, previously exposed to anesthetics, is protected against future insult. It presumes a sub-lethal injury, affecting protein unfolding. Our hypothesis is: preconditioning evokes molecular events that result in downstream changes that offer a selective advantage in terms of neuronal function. We focused on the neurobehavioral aspects which we neurophenotyped. Larval zebrafish were exposed to trifluoroethanol (TFE), an anesthetic mimetic, and tested for both individual and group behavioral markers of neuronal function. In bright/dark tests, we observed that TFE-exposed larvae spent more time in the dark area (typically an adult-like response) than control larvae. The response of TFE larvae to noise startle was directly opposite to that of controls. TFE larvae swam towards the source of the startle (into the bright zone), whereas control larvae swam away from the source of the startle (into the dark), typical of fear-response. The larvae also exhibited several differences in social behaviors, including synchronized schooling and shoaling behaviors. The TFE-group showed a greater number of synchronized events versus controls. The TFE-group also exhibited more shoaling events compared with controls. While the long-term effects have yet to be determined, these results shed light on the mechanism of anesthetic preconditioning. These complex zebrafish behaviors normally develop with age and therefore represent, in the TFE-exposed group, a pattern of accelerated maturation of neuronal function, which is the neurophenotype attributed to preconditioning.