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By implementation of sonography regional anesthesia became more relevant in the daily practice of anesthesia and pain therapy. Due to visualized needle guidance ultrasound supports more safety during needle placement. Thereby new truncal blocks got enabled. Next to the blocking of specific nerve structures, plane blocks got established which can also be described as interfascial compartment blocks. The present review illustrates published and established blocks in daily practice concerning indications and the procedural issues. Moreover, the authors explain potential risks, complications and dosing of local anesthetics.
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Anestesia de Conducción , Anestesia Local , Humanos , Anestesia de Conducción/métodos , Anestésicos Locales , Manejo del Dolor/métodos , Abdomen/diagnóstico por imagen , Abdomen/cirugía , Ultrasonografía Intervencional/métodosRESUMEN
This review article provides an overview of current developments in peripheral regional anaesthesia (RA). The authors present a subjective compilation based on discussions at professional events and inquiries to the Working Group on Regional Anaesthesia of the German Society for Anaesthesiology and Intensive Care Medicine (DGAI). The article addresses several relevant topics, including the handling of antithrombotic medication in peripheral blockades with reference to European guidelines, the debate on the discharge timing after plexus anaesthesia, and the consideration of rebound pain as an independent pain entity following RA.Furthermore, the contentious discussion regarding the administration of peripheral nerve blockades under general anaesthesia is illuminated. The authors express no fundamental concerns in this regard but emphasize the importance of preoperative evaluation and individual patient needs. The question of mixing local anaesthetics is also addressed, with the authors critically questioning this tradition and recommending the use of individual, long-acting substances.Another focal point is the application of peripheral nerve blockades in emergency medicine, both in preclinical and emergency room settings. The authors highlight the necessity for high-quality studies and discuss the complex organizational issues associated with the preclinical application of RA techniques.
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Anestesia de Conducción , Anestesiología , Humanos , Anestesia Local , Anestésicos Locales , DolorRESUMEN
BACKGROUND: Needle visualization is essential to avoid vascular puncture and nerve injury in ultrasound-guided regional anesthesia. Several factors that statistically influence needle visibility have been described but the dimensions of their individual impact remain unclear. This study aimed to quantify the impact of various independent factors on ultrasound needle visibility. METHODS: A total of 1500 ultrasound videos of in-plane needle insertions were obtained in embalmed cadavers with ten different commercially available echogenic and non-echogenic needles at different insertion angles and bevel orientations in a full factorial study design. The visibility of needle tip and shaft were rated as "good" or "poor" visibility. Nominal logistic regression analyses were calculated for the visibility of the needle tip and shaft. RESULTS: SonoPlex Stim Sprotte, SonoTAP Facet (needle tip and shaft) and Spinostar PencilPoint (needle tip)), insertion angle and bevel orientation were associated with good ultrasound visibility, reaching statistical significance (p < 0.05). The range of the effect on the log-odds scale for needle tip visibility was largest for the insertion angle with 6.33, followed by the tissue condition (3.76), bevel orientation (1.45) and the needle types (1.25). Regarding the needle shaft visibility, the largest effect range was observed with the insertion angle (7.36), followed by the tissue conditions with 3.96, needle type (1.86) and bevel orientation (0.95). CONCLUSION: In-plane needle visibility in ultrasound images depends mainly on the insertion angle, as expected. This is closely followed by the tissue condition, which is a factor related to the patient, thus cannot be altered to improve needle visibility. In the dimensions of the log-odds scale, the choice of a specific needle is far less important towards achieving a good visualization, whereas optimizing the bevel orientation can have a larger impact than the needle choice. Concluding from the relative dimensions of factors that determine needle visibility in this model, the importance of needles with echogenic features may be overrated.
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Anestesia de Conducción , Ultrasonografía Intervencional , Humanos , Ultrasonografía Intervencional/métodos , Modelos Logísticos , Ultrasonografía/métodos , Anestesia de Conducción/métodos , Agujas , CadáverRESUMEN
BACKGROUND: In 2019, the German prehospital airway management guidelines were published. One of the recommendations was the primary utilization of videolaryngoscopy (VL) for every prehospital endotracheal intubation (phETI). Guideline compliance is extremely important in emergency medicine as non-compliance in the worst-case scenario leads to death. The study aims to quantify guideline compliance among emergency medical service (EMS) physicians and, subsequently to analyze subgroups influencing compliance. MATERIAL AND METHODS: An online survey was developed and distributed as a hyperlink via email to all medical directors of EMS (nâ¯= 155) and the three main operators of helicopter emergency medical services (HEMS) in Germany. The survey was online from August 1st 2021 until October 3rd 2021. The primary outcome measure was the primary VL utilization. Data were evaluated descriptively. A multivariate regression analysis was used to determine associations between the primary VL utilization and age, sex, educational level, specialization, phETI per year, operating field, VL device type, and guideline knowledge. RESULTS: The analysis included 698 EMS physicians. More than 55% of the EMS physicians do not primarily use a videolaryngoscope for phETI. Multivariate regression analysis showed a significantly higher compliance if the devices CMAC® or McGrath® were on board, guidelines were known or EMS physicians were female. Age, educational level, specialization or prehospital intubation experience had no significant impact. CONCLUSION: The study shows non-compliance with prehospital airway management guidelines in Germany. The guideline recommendation is based on scientific evidence but is not yet generally accepted by all EMS physicians. Videolaryngoscope device type and sex seem to influence the primary VL utilization. Training for EMS physicians must be extended and individual prehospital airway management should be reconsidered by every EMS physician.
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Servicios Médicos de Urgencia , Laringoscopía , Humanos , Femenino , Masculino , Manejo de la Vía Aérea , Intubación Intratraqueal , AlemaniaRESUMEN
BACKGROUND: Patients suffering from severe trauma experience substantial immunological stress. Lung injury is a known risk factor for the development of posttraumatic complications, but information on the long-term course of the pulmonary inflammatory response and treatment with mild hypothermia are scarce. AIM: To investigate the pulmonary inflammatory response to multiple trauma and hemorrhagic shock in a porcine model of combined trauma and to assess the immunomodulatory properties of mild hypothermia. METHODS: Following induction of trauma (blunt chest trauma, liver laceration, tibia fracture), two degrees of hemorrhagic shock (45 and 50%) over 90 (n = 30) and 120 min. (n = 20) were induced. Animals were randomized to hypothermia (33°C) or normothermia (38°C). We evaluated bronchoalveolar lavage (BAL) fluid and tissue levels of cytokines and investigated changes in microRNA- and gene-expression as well as tissue apoptosis. RESULTS: We observed a significant induction of Interleukin (IL) 1ß, IL-6, IL-8, and Cyclooxygenase-2 mRNA in lung tissue. Likewise, an increased IL-6 protein concentration could be detected in BAL-fluid, with a slight decrease of IL-6 protein in animals treated with hypothermia. Lower IL-10 protein levels in normothermia and higher IL-10 protein concentrations in hypothermia accompanied this trend. Tissue apoptosis increased after trauma. However, intervention with hypothermia did not result in a meaningful reduction of pro-inflammatory biomarkers or tissue apoptosis. CONCLUSION: We observed signs of a time-dependent pulmonary inflammation and apoptosis at the site of severe trauma, and to a lower extent in the trauma-distant lung. Intervention with mild hypothermia had no considerable effect during 48 hours following trauma.
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Traumatismo Múltiple , Choque Hemorrágico , Traumatismos Torácicos , Heridas no Penetrantes , Animales , Interleucina-10 , Interleucina-6 , Pulmón , Traumatismo Múltiple/complicaciones , Traumatismo Múltiple/terapia , Choque Hemorrágico/terapia , Porcinos , Traumatismos Torácicos/complicaciones , Traumatismos Torácicos/terapiaRESUMEN
INTRODUCTION: Amino-amide local anesthetics precipitate when mixed with some commonly used adjuvants, carrying the risk of perineural or vascular crystal deposition. The aim of this study was to evaluate whether crystallization occurs with routinely used local anesthetic-adjuvant combinations and if a relation with the solution's pH exists. METHODS: All substances used in this trial were first visually investigated undiluted under tenfold magnification. Grade of crystallization was assessed using a 6 point grading system.Ropivacaine (0.2%, 0.75% and 1%) and bupivacaine (0.25% and 0.5%) were mixed in a 1:1 solution with the following adjuvants: dexamethasone, dexmedetomidine, clonidine, fentanyl, sodium bicarbonate 8.4% and sodium chloride 0.9%. Subsequently, ropivacaine (0.2% and 0.75%) and bupivacaine (0.25% and 0.5%) were mixed with adjuvants in concentrations commonly used in clinical practice and then serially assessed at several time points up to 1 hour. pH of all substances/combinations was assessed and correlated with crystallization grade. RESULTS: All pure substances-except the reference standards sterile water and triamcinolon-showed crystallization grades ranging from grade 1 to grade 4. Addition of adjuvants lead to variable, unpredictable changes in crystal depositions. Addition of sodium bicarbonate 8.4% produced heavy crystallization in all combinations. Grade of crystallization was weakly positively related to the pH of the solution in 1:1 mixtures and clinically relevant concentrations, but not in pure substances. DISCUSSION: Our study showed that crystallization is present in pure local anesthetics and may be increased or decreased by admixture of adjuvants. Higher pH of mixtures was weakly associated with more crystallization. Further research is necessary to translate these findings into clinical practice.
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One of the main limitations concerning the use of local anesthetics is due to their restricted duration of action. In recent years, liposomal formulations with prolonged release kinetics have been developed to extend the pharmacological duration of action of the 1stage peripheral regional anesthesia (single-shot procedure) and thus bring about a longer duration of action. The focus here is particularly on achieving postoperative freedom from pain for at least 24â¯h (or even better 48â¯h) and thus early mobilization of patients using on-demand medication causing (at most) minor local sensory blockade without causing motor impairments (at least that is the ideal). Therefore, methods of utilizing slow-release drugs as seen in liposomal carrier systems have experienced increasing scientific attention in the last few years. A common modern pharmacological example with a theoretically significantly longer duration of action is liposomal bupivacaine, an amide local anesthetic. Due to a multivesicular liposome structure, the retarded release of the active component bupivacaine HCl leads to a theoretical pharmacological effectiveness of up to 72â¯h. Previous studies consistently showed a safety profile comparable to conventional bupivacaine HCl. Liposomal bupivacaine has been approved by the U.S. Food and Drug Administration (FDA) under the trade name Exparel© (Pacira Pharmaceuticals, Parsippany, NJ, USA) since 2011; however, its use is currently limited to local wound infiltration, transverse abdominis plane (TAP) blocks, and interscalene nerve blocks of the brachial plexus. In 2020, the European Medicines Agency (EMA) also approved the use of liposomal bupivacaine for blockade of the brachial plexus or the femoral nerve and as a field block or for wound infiltration to treat postoperative pain. So far, studies on the clinical effectiveness of liposomal bupivacaine have been very heterogeneous and there have been no conclusive meta-analyses with sufficient rigor or significance. Recent systematic reviews and meta-analyses, combining the results of clinical studies regarding the analgesic efficiency of liposomal bupivacaine in different fields of application, consistently refuted any benefit of clinical relevance provided by the liposomal formulation. There is currently sufficient evidence to now end the ongoing debate around liposomal bupivacaine. The aim of this work is to give the reader a current, evidence-based overview of this substance.
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Anestesia de Conducción , Bloqueo Nervioso , Anestésicos Locales/uso terapéutico , Bupivacaína/uso terapéutico , Humanos , Liposomas , Bloqueo Nervioso/métodos , Dolor Postoperatorio/tratamiento farmacológicoRESUMEN
BACKGROUND: Evidence concerning combined general anesthesia (GA) and thoracic epidural analgesia (EA) is controversial and the procedure appears heterogeneous in clinical implementation. We aimed to gain an overview of different approaches and to unveil a suspected heterogeneity concerning the intraoperative management of combined GA and EA. METHODS: This was an anonymous survey among Members of the Scientific working group for regional anesthesia within the German Society of Anaesthesiology and Intensive Care Medicine (DGAI) conducted from February 2020 to August 2020. RESULTS: The response rate was 38%. The majority of participants were experienced anesthetists with high expertise for the specific regimen of combined GA and EA. Most participants establish EA in the sitting position (94%), prefer early epidural initiation (prior to skin incision: 80%; intraoperative: 14%) and administer ropivacaine (89%) in rather low concentrations (0.2%: 45%; 0.375%: 30%; 0.75%: 15%) mostly with an opioid (84%) in a bolus-based mode (95%). The majority reduce systemic opioid doses intraoperatively if EA works sufficiently (minimal systemic opioids: 58%; analgesia exclusively via EA: 34%). About 85% manage intraoperative EA insufficiency with systemic opioids, 52% try to escalate EA, and only 25% use non-opioids, e.g. intravenous ketamine or lidocaine. CONCLUSIONS: Although, consensus seems to be present for several aspects (patient's position during epidural puncture, main epidural substance, application mode), there is considerable heterogeneity regarding systemic opioids, rescue strategies for insufficient EA, and hemodynamic management, which might explain inconsistent results of previous trials and meta-analyses.
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Analgesia Epidural , Anestesia Epidural , Anestesia General , Anestesistas , Humanos , Dolor Postoperatorio , RopivacaínaRESUMEN
BACKGROUND AND OBJECTIVES: Injection pressure monitoring can help detecting the needle tip position and avoid intraneural injection. However, it shall be measured at the needle tip in order to be accurate and reproducible with any injection system and non operator-dependent. With an innovative system monitoring the injection pressure right at the needle tip we show that it is possible to early detect an intraneural and also an intravascular injection. METHODS: We performed supraclavicular block-like procedures under real-time ultrasound guidance on two fresh cadaver torsos using a sensing needle with an optical fiber pressure sensor within the shaft continuously measuring injection pressure at the needle tip. A total of 45 ultrasound-guided injections were performed (15 perineural, 15 intraneural and 15 intravenous injections). RESULTS: Mean (SD) injection pressure after only 1 mL injected volume was already significantly higher for the intraneural compared to the perineural injections: 70.46 kPa (11.72) vs 8.34 (4.68) kPa; P < .001. Mean (SD) injection pressure at 1 mL injected volume was significantly lower for the intravascular compared to the perineural injections: 1.51 (0.48) vs 8.34 (4.68) kPa; P < .001. CONCLUSIONS: Our results show that injection pressure monitoring at the needle tip has the potential to help identifying an accidental intraneural or intravascular injection at a very early stage.
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Bloqueo del Plexo Braquial , Agujas , Cadáver , Humanos , Inyecciones Intravenosas , Ultrasonografía IntervencionalRESUMEN
Background: Proportions of patients dying from the coronavirus disease-19 (COVID-19) vary between different countries. We report the characteristics; clinical course and outcome of patients requiring intensive care due to COVID-19 induced acute respiratory distress syndrome (ARDS). Methods: This is a retrospective, observational multicentre study in five German secondary or tertiary care hospitals. All patients consecutively admitted to the intensive care unit (ICU) in any of the participating hospitals between March 12 and May 4, 2020 with a COVID-19 induced ARDS were included. Results: A total of 106 ICU patients were treated for COVID-19 induced ARDS, whereas severe ARDS was present in the majority of cases. Survival of ICU treatment was 65.0%. Median duration of ICU treatment was 11 days; median duration of mechanical ventilation was 9 days. The majority of ICU treated patients (75.5%) did not receive any antiviral or anti-inflammatory therapies. Venovenous (vv) ECMO was utilized in 16.3%. ICU triage with population-level decision making was not necessary at any time. Univariate analysis associated older age, diabetes mellitus or a higher SOFA score on admission with non-survival during ICU stay. Conclusions: A high level of care adhering to standard ARDS treatments lead to a good outcome in critically ill COVID-19 patients.
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BACKGROUND: Skeletal muscle microvascular blood flow plays a critical role in many myopathologies. The influence of bupivacaine and adjuvants on skeletal muscle microvascular perfusion and tissue oximetry is poorly understood but might be a relevant risk factor for myopathies after local anesthetic administration. The aim of this experimental study was to determine the effects of bupivacaine alone or in combination with epinephrine or clonidine on skeletal muscle perfusion and tissue oximetry. METHODS: Combined tissue spectrophotometry and Laser-Doppler flowmetry and tissue oximetry were used to assess local muscle blood flow in anesthetized pigs after topical administration of test solutions (bupivacaine, bupivacaine with epinephrine or clonidine, saline). Measurements were performed for up to 60 mins. RESULTS: The application of bupivacaine alone did not alter relative muscle blood flow significantly, whereas the addition of epinephrine or clonidine to bupivacaine resulted in a significant reduction of relative muscle blood flow at T30 and T60. However, bupivacaine resulted in a significant decrease of tissue oximetry values when compared to saline control group at T30 and T60. The application of bupivacaine combined with clonidine or epinephrine resulted in no significant reduction of tissue oximetry when compared to bupivacaine alone. CONCLUSION: Bupivacaine alone results in a significant decrease of tissue oximetry in skeletal muscle which is not increased by the addition of epinephrine or clonidine despite further reductions of microcirculatory perfusion. Overall, bupivacaine alone or with adjuvants does produce local muscle ischemia for which pathological consequences need to be addressed in further studies.
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Ultrasound has significantly increased safety and effectiveness in regional anesthesia. However, little is known about its clinical use. We studied clinical approaches currently used by anesthesiologists, conducted a nationwide survey, and analyzed data collected in ordered logistic regression models. All active members of the Swiss Society for Anaesthesiology and Resuscitation (SSAR/SGAR) were asked to participate. Reported practice in nerve localization, safety, and techniques used for peripheral nerve blocks (PNB) were main outcome measures. Experience ranged from 3 to >30 years. The mean number of block techniques mastered was 11.5 ± 5.9. Standard monitoring was regularly used, whereas sterile coats were less frequently used by anesthesiologists who self-estimated a higher level of expertise in PNB (ordered logit coefficient -0.05, 95% CI -0.07 to -0.02, P < 0.001; pseudo r2 = 0.019; probability > Chi2 = 0.02). The more self-estimated expertise anesthesiologists had, the less likely they were to use nerve stimulation in combination with ultrasound (dual guidance) (ordered logit coefficient -0.31; 95% CI -0.85 to -0.03: P = 0.03; pseudo r2 = 0.007; probability > Chi2 = 0.05). The high share of reported standard monitoring meets the recommendations of the Helsinki Patient Safety Declaration. Dual guidance appears to be the preferred approach for safely localizing nerves for PNB in Switzerland.
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Anestesiólogos , Bloqueo Nervioso/métodos , Nervios Periféricos/diagnóstico por imagen , Anestésicos Locales/uso terapéutico , Femenino , Humanos , Masculino , Práctica Profesional , Encuestas y Cuestionarios , Suiza , Ultrasonografía IntervencionalRESUMEN
Peripheral regional anesthesia procedures, such as femoral nerve block, are relatively safe procedures in clinical anesthesia. Nevertheless, it may lead to typical, usually transient and rarely even persistent complications. This article aims to highlight key aspects of complications in peripheral regional anesthesia and, in particular, strategies to reduce risk. Moreover, beside general complications, which might potentially occur in any peripheral nerve blockade ("bleeding/infection/nerve damage"), accidental co-blockades of other nerval structures are discussed using the example of the brachial plexus. In addition to the presentation of the possible complications, this article discusses improvements in the techniques during the last two decades. Due to the use of ultrasound, some side effects nowadays are supposed to occur less likely. An outlook into the future will inform the reader about improved or more selective blockages.
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Anestesia de Conducción/métodos , Dolor Postoperatorio/terapia , Anestesia de Conducción/efectos adversos , Anestésicos Locales/administración & dosificación , Anestésicos Locales/efectos adversos , Bloqueo del Plexo Braquial/efectos adversos , Bloqueo del Plexo Braquial/métodos , Humanos , Complicaciones Posoperatorias/epidemiología , Ultrasonografía IntervencionalRESUMEN
BACKGROUND: Combining continuous femoral nerve blockade with single injection sciatic nerve blockade is standard peripheral nerve block practice for total knee arthroplasty (TKA) during the first 24 postoperative hours. OBJECTIVES: To assess the analgesic benefits and mobilisation capability of continuous sciatic blockade in conjunction with continuous femoral nerve blockade for 72âh after arthroplasty. DESIGN: Randomised, triple-blinded controlled trial. SETTING: Single-Centre, German University Hospital. PATIENTS: In total, 50 patients receiving continuous femoral nerve blockade (5âmlâh ropivacaine 0.2%) for TKA under general anaesthesia. INTERVENTIONS: Patients were randomised to receive a sciatic nerve catheter with an initial dose of 10âml ropivacaine 0.2% followed by either continuous double-blinded application of 5âmlâh ropivacaine 0.2% (CO) or 5âmlâh saline infusion (SIN). MAIN OUTCOME: Measures primary endpoint: cumulative morphine consumption until 48âh postoperatively. Further endpoints included morphine consumption, pain scores, mobilisation, dynamometry until postoperative day 3. RESULTS: Median [25th to 75th percentiles] cumulative morphine consumption at postoperative day 2 differed significantly between groups (CO 15âmg [11 to 25] versus SIN, 43âmg [27 to 67.5, Pâ<â0.0001) in the 48 patients in the final analysis. Overall pain scores were comparable at rest and during stress at each time point. However, significantly higher pain scores of the popliteal fossa were observed in the SIN group. Mobilisation was comparable between groups. CONCLUSION: This trial demonstrates the superior analgesic effects of continuous sciatic nerve block compared with a single injection in combination with continuous femoral blockade during the first 72âh after TKA. However, mobilisation capability was impaired in both groups. Improved pain control from two catheters needs to be balanced against the potential risks of impaired mobilisation and patient falls. TRIAL REGISTRATION: DRKS - German clinical trials register (no: DRKS00010152).
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Artroplastia de Reemplazo de Rodilla/métodos , Bloqueo Nervioso Autónomo/métodos , Manejo del Dolor/métodos , Dolor Postoperatorio/diagnóstico por imagen , Nervio Ciático/diagnóstico por imagen , Ultrasonografía Intervencional/métodos , Anciano , Artroplastia de Reemplazo de Rodilla/normas , Bloqueo Nervioso Autónomo/normas , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Manejo del Dolor/normas , Dolor Postoperatorio/prevención & control , Nervio Ciático/efectos de los fármacos , Ultrasonografía Intervencional/normasRESUMEN
BACKGROUND: Nerve blood flow has a critical role in acute and chronic pathologies in peripheral nerves. Influences of local anesthetics and adjuvants on tissue perfusion and oxygenation are deemed as relevant factors for nerve damage after peripheral regional anesthesia. The link between low tissue perfusion due to local anesthetics and resulting tissue oxygenation is unclear. METHODS: Combined tissue spectrophotometry and laser-Doppler flowmetry were used to assess nerve blood flow in 40 surgically exposed median nerves in pigs, as well as nerve tissue oximetry for 60 min. After baseline measurements, test solutions saline (S), bupivacaine (Bupi), bupivacaine with epinephrine (BupiEpi), and bupivacaine with clonidine (BupiCloni) were applied topically. RESULTS: Bupivacaine resulted in significant decrease in nerve blood flow, as well as tissue oximetry values, compared with saline control. Addition of epinephrine resulted in a rapid, but nonsignificant, reduction of nerve blood flow and extensive lowering of tissue oximetry levels. The use of clonidine resulted in a reduction of nerve blood flow, comparable to bupivacaine alone (relative blood flow at T60 min compared with baseline, S: 0.86 (0.67-1.18), median (25th-75th percentile); Bupi: 0.33 (0.25-0.60); BupiCloni: 0.43 (0.38-0.63); and BupiEpi: 0.41(0.30-0.54). The use of adjuvants did not result in any relevant impairment of tissue oximetry values (saturation values in percent at T60, S: 91.5 [84-95]; Bupi: 76 [61-86]; BupiCloni: 84.5 [76-91]; and BupiEpi: 91 [56-92]). CONCLUSION: The application of bupivacaine results in lower nerve blood flow, but does not induce relevant ischemia. Despite significant reductions in nerve blood flow, the addition of clonidine or epinephrine to bupivacaine had no significant impact on nerve tissue oximetry compared with bupivacaine alone. Nerve ischemia due to local anesthetics is not enhanced by the adjuvants clonidine or epinephrine.
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Multiple trauma (MT) associated with hemorrhagic shock (HS) might lead to cerebral hypoperfusion and brain damage. We investigated cerebral alterations using a new porcine MT/HS model without traumatic brain injury (TBI) and assessed the neuroprotective properties of mild therapeutic hypothermia. Male pigs underwent standardized MT with HS (45% or 50% loss of blood volume) and resuscitation after 90/120 min (T90/T120). In additional groups (TH90/TH120) mild hypothermia (33°C) was induced following resuscitation. Normothermic or hypothermic sham animals served as controls. Intracranial pressure, cerebral perfusion pressure (CPP), and cerebral oxygenation (PtiO2) were recorded up to 48.5âh. Serum protein S-100B and neuron-specific enolase (NSE) were measured by ELISA. Cerebral inflammation was quantified on hematoxylin and eosin -stained brain slices; Iba1, S100, and inducible nitric oxide synthase (iNOS) expression was assessed using immunohistochemistry. Directly after MT/HS, CPP and PtiO2 were significantly lower in T90/T120 groups compared with sham. After resuscitation both parameters showed a gradual recovery. Serum protein S-100B and NSE increased temporarily as a result of MT/HS in T90 and T90/T120 groups, respectively. Cerebral inflammation was found in all groups. Iba1-staining showed significant microgliosis in T90 and T120 animals. iNOS-staining indicated a M1 polarization. Mild hypothermia reduced cerebral inflammation in the TH90 group, but resulted in increased iNOS activation. In this porcine long-term model, we did not find evidence of gross cerebral damage when resuscitation was initiated within 120 min after MT/HS without TBI. However, trauma-related microglia activation and M1 microglia polarization might be a consequence of temporary hypoxia/ischemia and further research is warranted to detail underlying mechanisms. Interestingly, mild hypothermia did not exhibit neuroprotective properties when initiated in a delayed fashion.
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Cerebro/patología , Traumatismo Múltiple/patología , Choque Hemorrágico/patología , Animales , Astrocitos/metabolismo , Astrocitos/patología , Lesiones Encefálicas/patología , Circulación Cerebrovascular/fisiología , Cerebro/metabolismo , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Hipotermia Inducida , Inmunohistoquímica , Presión Intracraneal/fisiología , Masculino , Microglía/metabolismo , Microglía/patología , Óxido Nítrico Sintasa de Tipo II/metabolismo , PorcinosRESUMEN
OBJECTIVE: Identification of peripheral nerve tissue is crucial in both surgery and regional anesthesia. Recently, optical tissue identification methods are presented to facilitate nerve identification in transcutaneous procedures and surgery. Optimization and validation of such techniques require large datasets. The use of alternative models to human in vivo, like human post mortem, or swine may be suitable to test, optimize and validate new optical techniques. However, differences in tissue characteristics and thus optical properties, like oxygen saturation and tissue perfusion are to be expected. This requires a structured comparison between the models. STUDY DESIGN: Comparative observational study. METHODS: Nerve and surrounding tissues in human (in vivo and post mortem) and swine (in vivo and post mortem) were structurally compared macroscopically, histologically, and spectroscopically. Diffuse reflective spectra were acquired (400-1,600 nm) after illumination with a broad band halogen light. An analytical model was used to quantify optical parameters including concentrations of optical absorbers. RESULTS: Several differences were found histologically and in the optical parameters. Histologically nerve and adipose tissue (subcutaneous fat and sliding fat) showed clear similarities between human and swine while human muscle enclosed more adipocytes and endomysial collagen. Optical parameters revealed model dependent differences in concentrations of ß-carotene, water, fat, and oxygen saturation. The similarity between optical parameters is, however, sufficient to yield a strong positive correlation after cross model classification. CONCLUSION: This study shows and discusses similarities and differences in nerve and surrounding tissues between human in vivo and post mortem, and swine in vivo and post mortem; this could support the discussion to use an alternative model to optimize and validate optical techniques for clinical nerve identification. Lasers Surg. Med. 50:253-261, 2018. © 2017 Wiley Periodicals, Inc.