Editorial: Safety monitoring for peripheral nerve blocks - Is there a state-of-the-art standard to avoid nerve injuries?

Highlights • Since there is only a low level of evidence, it is difficult to agree on state-of-the-art standards or to provide recommendations and guidelines. • The value of combining several monitoring devices for dual or triple guidance must be challenged. • The principle of fascial plane blocks is suitable to avoid traumatic needle-to-nerve contact. However, local toxicity must be regarded as a possible mechanism for nerve injuries. • Block procedures might be conducted during sedation or general anesthesia when considering the individual patients' clinical situations and the expertise of the anesthesiologist. • The quality of ultrasound equipment and education provided by the corresponding anesthesia department is highly relevan

Hemodynamic impact of isobaric levobupivacaine versus hyperbaric bupivacaine for subarachnoid anesthesia in patients aged 65 and older undergoing hip surgery

BackgroundThe altered hemodynamics, and therefore the arterial hypotension is the most prevalent adverse effect after subarachnoid anesthesia. The objective of the study was to determine the exact role of local anesthetic selection underlying spinal anesthesia-induced hypotension in the elderly patient. We conducted a descriptive, observational pilot study to assess the hemodynamic impact of subarachnoid anesthesia with isobaric levobupivacaine versus hyperbaric bupivacaine for hip fracture surgery.DescriptionHundred twenty ASA status I-IV patients aged 65 and older undergoing hip fracture surgery were enrolled. The primary objective of our study was to compare hemodynamic effects based on systolic blood pressure (SBP) and dyastolic blood pressure (DBP) values, heart rate (HR) and hemoglobin (Hb) and respiratory effects based on partial oxygen saturation (SpO2%) values. The secondary objective was to assess potential adverse events with the use of levobupivacaine versus bupivacaine. Assessments were performed preoperatively, at 30 minutes into surgery, at the end of anesthesia and at 48 hours and 6 months after surgery.Among intraoperative events, the incidence of hypotension was statistically significantly higher (p <0.05) in group BUPI (38.3%) compared to group LEVO (13.3%). There was a decrease (p <0.05) in systolic blood pressure (SBP) and diastolic blood pressure (DBP) at 30 minutes intraoperatively (19% in group BUPI versus 17% in group LEVO). SpO2% increased at 30 minutes after anesthesia onset (1% in group BUPI versus 1.5% in group LEVO). Heart rate (HR) decreased at 30 minutes after anesthesia onset (5% in group BUPI versus 9% in group L). Hemoglobin (Hb) decreased from time of operating room (OR) admission to the end of anesthesia (9.3% in group BUPI versus 12.5% in group LEVO). The incidence of red blood cell (RBC) transfusion was 13.3% in group BUPI versus 31.7% in group LEVO, this difference was statistically significant. Among postoperative events, the incidence of congestive heart failure (CHF) was significantly higher in group BUPI (8,3%). At 6 months after anesthesia, no differences were found.ConclusionsGiven the hemodynamic stability and lower incidence of intraoperative hypotension observed, levobupivacaine could be the agent of choice for subarachnoid anesthesia in elderly patients

The IFN-γ-Inducible GTPase, Irga6, Protects Mice against Toxoplasma gondii but Not against Plasmodium berghei and Some Other Intracellular Pathogens

Clearance of infection with intracellular pathogens in mice involves interferon-regulated GTPases of the IRG protein family. Experiments with mice genetically deficient in members of this family such as Irgm1(LRG-47), Irgm3(IGTP), and Irgd(IRG-47) has revealed a critical role in microbial clearance, especially for Toxoplasma gondii. The in vivo role of another member of this family, Irga6 (IIGP, IIGP1) has been studied in less detail. We investigated the susceptibility of two independently generated mouse strains deficient in Irga6 to in vivo infection with T. gondii, Mycobacterium tuberculosis, Leishmania mexicana, L. major, Listeria monocytogenes, Anaplasma phagocytophilum and Plasmodium berghei. Compared with wild-type mice, mice deficient in Irga6 showed increased susceptibility to oral and intraperitoneal infection with T. gondii but not to infection with the other organisms. Surprisingly, infection of Irga6-deficient mice with the related apicomplexan parasite, P. berghei, did not result in increased replication in the liver stage and no Irga6 (or any other IRG protein) was detected at the parasitophorous vacuole membrane in IFN-γ-induced wild-type cells infected with P. berghei in vitro. Susceptibility to infection with T. gondii was associated with increased mortality and reduced time to death, increased numbers of inflammatory foci in the brains and elevated parasite loads in brains of infected Irga6-deficient mice. In vitro, Irga6-deficient macrophages and fibroblasts stimulated with IFN-γ were defective in controlling parasite replication. Taken together, our results implicate Irga6 in the control of infection with T. gondii and further highlight the importance of the IRG system for resistance to this pathogen

Der Einfluss der unisolierten Stromemissionsfläche an der Stimulationskanülenspitze während der Nervenlokalisation zur peripheren Regionalanästhesie

Einleitung: Die elektrische Nervenstimulation ist ein etabliertes Standardverfahren zur Nervenlokalisation bei der Durchführung peripherer Nervenblockaden. Neurologische Defizite nach peripheren Regionalanästhesien lassen sich jedoch trotz Berücksichtigung vermeintlich nervenschonender Techniken bisher nicht vollends vermeiden und stellen ein klinisch relevantes Problem dar. Als häufige Ursache wird die Nervenverletzung während der Kanülenplatzierung diskutiert. Nadel-Nerv-Kontakte gelten als gesicherter Risikofaktor für Nervenschäden. Die verfügbaren Designs isolierter Stimulationskanülen unterscheiden sich zum Teil beträchtlich in der Größe ihrer Stromemissionsfläche. Bisher liegen keine vergleichenden Daten zur Inzidenz von Nadel-Nerv-Kontakten in Abhängigkeit von der Emissionsfläche vor. Material und Methoden: An sechs anästhesierten Schweinen wurde am offenen Plexus brachialis eine Nadel-Nerv-Distanzmessung bei minimaler Reizantwort unter Anwendung eines Schwellenstroms von 0,3 bis 0,8 mA durchgeführt. Es wurden drei Kanülentypen untersucht: Stimuplex® A (Standardkanüle mit mittlerer Emissionsfläche, n = 2025), Stimuplex® D (kleine Emissionsfläche, n = 1800) und eine Tuohy-Kanüle (StimucathTM, große Emissionsfläche, n = 2025). Die relativen Häufigkeiten für Nadel-Nerv-Kontakte wurden mittels Fishers Exact Test verglichen. Unterschiede zwischen den Nadel-Nerv-Abständen wurden mittels Friedman-Test und anschließendem Paarvergleich ermittelt. Ergebnisse: Insgesamt wurden 5850 Stimulationsversuche durchgeführt. Im Intervall 0,3 - 0,5 mA fand sich eine hohe Anzahl an unerwünschten Nadel-Nerv-Kontakten. Im Niedrigstrombereich traten zudem Nadel-Nerv-Kontakte ohne begleitende Stimulationsantwort auf. Die höchste Stimulationsversagerrate wies die Tuohy-Kanüle auf, gefolgt von der Stimuplex® D und der Stimuplex® A. Der Unterschied zwischen den untersuchten Nadeltypen war signifikant (p < 0,0001 für 0,3 mA). Im Intervall 0,6 - 0,8 mA wies die Stimuplex® A die geringste Inzidenz von Nadel-Nerv-Kontakten auf und unterschied sich signifikant von den beiden anderen Kanülen (Stimuplex® A vs. Stimuplex® D p < 0,005 für 0,6 mA, p < 0,0001 für 0,7 mA, p < 0,005 für 0,8 mA, Stimuplex® A vs. Tuohy p < 0,0001 für 0,6 mA bis 0,8 mA). Für die Tuohy-Nadel zeigte sich im Vergleich zur Stimuplex® D eine höhere Inzidenz von Nadel-Nerv-Kontakten. Schlussfolgerung: Beim Einsatz von Stimulationskanülen mit kleinen Emissionsflächen treten Nadel-Nerv-Kontakte nicht seltener auf als bei der Verwendung von Kanülen mit großen Emissionsflächen. Dennoch implizieren die signifikanten Unterschiede in der Inzidenz von Nadel-Nerv-Kontakten mit und ohne Stimulationserfolg differente Stimulationseigenschaften der unterschiedlichen Kanülenmodelle. Das Tuohy-Design scheint besonders anfällig für Nadel-Nerv-Kontakte und das Ausbleiben einer Reizantwort bei unmittelbarer Berührung des Zielnerven. Bei Stimulation mit Strömen oberhalb von 0,5 mA ist im Vergleich zu niedrigeren Schwellenwerten unabhängig vom Kanülendesign von einer größeren Sicherheit durch seltenere Nadel-Nerv-Kontakte bei vergleichbarer Nähe der Stimulationsnadel zum Nerv auszugehen. Darüber hinaus variiert der optimale Stimulationsstrom in Abhängigkeit vom verwendeten Kanülentyp

Nerventrauma in der peripheren Regionalanästhesie: Histopathologische Untersuchung peripherer Nerven nach Applikation von Stimulationsstrom am Tiermodell

Einleitung: Für periphere Regionalanästhesieverfahren wird zur Lokalisation von Nervenstrukturen die elektrische Nervenstimulation eingesetzt. Mit der vorliegenden Untersuchung sollte überprüft werden, inwiefern die applizierten Ströme als mögliche Ursache von auftretenden Nervenschäden in Betracht zu ziehen sind. In einem Tiermodell wurde histologisch untersucht, ob Stimulationsströme es vermögen, lokale aseptische Inflammationsreaktionen, intraneurale Einblutungen oder Myelinschäden auszulösen. Material und Methoden: Bei fünf Hausschweinen wurde der Plexus brachialis beidseitig freigelegt und die Nerven über 40s in einem Abstand von 0,5cm (1.5mA, 0,1ms, 2Hz) elektrisch stimuliert (Stimulationsgruppe, n=20). Nach 48h in Allgemeinanästhesie wurden die Regiones axillares erneut eröffnet und die behandelten Nerven sowie Kontrollen (n=25) zur histologischen Untersuchung entnommen (HE-, Klüver-Barrera-, Immunhistochemische Färbung). Es wurde das Ausmaß der traumabedingten Neuroinflammation, intraneuralen Hämatombildung und Myelinschädigung beurteilt. Die Auswertung erfolgte anhand eines histologischen Scores mit Werten von 0 (kein Schaden) bis 4 (schwerer Schaden). Ergebnisse: Nach histologischer Auswertung zeigte sich kein signifikanter Unterschied zwischen Stimulationsgruppe (1 [0/1]) (Median [25. Perzentile/75. Perzentile]) und Negativkontrolle (0 [0/1]), p=0,257. Schlussfolgerung: Auf Grundlage der angewandten Methodik löste die elektrische Nervenstimulation mit einer Stromstärke von 1,5 mA -ohne Nadel-Nerven Kontakt- keine histologischen Veränderungen im Sinne einer aseptischen Inflammation oder Myelinveränderungen aus. Demnach kann angenommen werden, dass die im klinischen Alltag beobachteten Nervenschäden nicht durch den bei der elektrischen Nervenstimulation eingesetzten Strom bedingt sind

Detection of needle to nerve contact based on electric bioimpedance and machine learning methods.

In an ongoing project for electrical impedance-based needle guidance we have previously showed in an animal model that intraneural needle positions can be detected with bioimpedance measurement. To enhance the power of this method we in this study have investigated whether an early detection of the needle only touching the nerve also is feasible. Measurement of complex impedance during needle to nerve contact was compared with needle positions in surrounding tissues in a volunteer study on 32 subjects. Classification analysis using Support-Vector Machines demonstrated that discrimination is possible, but that the sensitivity and specificity for the nerve touch algorithm not is at the same level of performance as for intra-neuralintraneural detection

Intraoperative management of combined general anesthesia and thoracic epidural analgesia: A survey among German anesthetists

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

A Swiss nationwide survey shows that dual guidance is the preferred approach for peripheral nerve blocks.

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  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

Early detection of intraneural and intravascular injections with real‐time injection pressure monitoring in cadavers

International audienceBackground 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