[Peripheral Regional Anesthesia Techniques - Standards in Flux?!]

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.

[Common and New Regional Anaesthesia Techniques Under Review - From Head to Abdomen]

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.

Nominal logistic regression analysis of variables determining needle visibility in ultrasound images - a full factorial cadaver study

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.

Analysis of the primary utilization of videolaryngoscopy in prehospital emergency care in Germany

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 (n = 155) and the three main operators of helicopter emergency medical services (HEMS) in Germany. The survey was online from August 1^st 2021 until October 3^rd 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 C‑MAC® 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.

Pulmonary inflammatory response and immunomodulation to multiple trauma and hemorrhagic shock in pigs

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) 1β, 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.

Crystallization of ropivacaine and bupivacaine when mixed with different adjuvants: a semiquantitative light microscopy analysis

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.

[Liposomal bupivacaine-No breakthrough in postoperative pain management]

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 1‑stage 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 24 h (or even better 48 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 72 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.

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.

COVID-19 Induced Acute Respiratory Distress Syndrome-A Multicenter Observational Study

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.

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

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.

[Peripheral truncal blocks-Overview and assessment]

By implementation of sonography for regional anesthesia, truncal blocks became more relevant in the daily practice of anesthesia and pain therapy. Due to visualized needle guidance ultrasound supports more safety and helps to avoid complications during needle placement. Additionally, complex punctures are possible that were associated with higher risk using landmarks alone. Next to the blocking of specific nerve structures, interfascial and compartment blocks have also become established, whereby the visualization of individual nerves and plexus structures is not of relevance. The present review article describes published and clinically established puncture techniques with respect to the indications and procedures. The clinical value is reported according to the scientific evidence and the analgesic profile. Moreover, the authors explain potential risks, complications and dosing of local anesthetic agents.

[Stocktaking of local anesthetics 2020]

For decades local anesthetics have proven to be safe and effective drugs in the clinical practice, crucially promoting the enormous achievements in regional anesthesia. Meanwhile, it is a well-known fact that local anesthetics are much more than just "simple" sodium channel blockers. They also interact with numerous other ion channels and subcellular structures, enhancing nerve blockade and resulting in systemic "alternative" effects, which can sometimes even be clinically used. By the simultaneous administration of various adjuvants (e.g., opioids, corticosteroids and α₂-receptor agonists) attempts are made to prolong the time of action of local anesthetics after a single administration in order to achieve the best possible improvement in postoperative analgesia. In this context, ultralong-acting local anesthetics, such as liposomal bupivacaine, which at least theoretically can provide a sensory nerve block for several days, have been developed and clinically introduced. The coming years will show whether these approaches will develop into genuine alternatives to the personnel and cost-intensive continuous nerve blockades.Local anesthetic-induced systemic toxicity is meanwhile rare but still a potentially life-threatening event, frequently resulting from accidental intravascular injection or extensive systemic resorption. Consequently, slow and fractional application of these agents with intermittent aspiration helps to prevent toxic sequelae. If toxic symptoms occur, however, the intravenous infusion of 20% lipid solutions in addition to basic treatment measures can enhance the success of treatment.

Effect of bupivacaine and adjuvant drugs on skeletal muscle tissue oximetry and blood flow: an experimental study

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.

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 < 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.

Hypothermia does not influence liver damage and function in a porcine polytrauma model

BACKGROUND

Previous studies revealed evidence that induced hypothermia attenuates ischemic organ injuries after severe trauma. In the present study, the effect of hypothermia on liver damage was investigated in a porcine long term model of multi-system injury, consisting of blunt chest trauma, penetrating abdominal trauma, musculoskeletal injury, and hemorrhagic shockMETHODS: In 30 pigs, a standardized polytrauma including blunt chest trauma, penetrating abdominal trauma, musculoskeletal injury, and hemorrhagic shock of 45% of total blood volume was induced. Following trauma, hypothermia of 33∘C was induced for 12 h and intensive care treatment was evaluated for 48 h. As outcome parameters, we assessed liver function and serum transaminase levels as well as a histopathological analysis of tissue samples. A further 10 animals served as controls.

RESULTS

Serum transaminase levels were increased at the end of the observation period following hypothermia without reaching statistical significance compared to normothermic groups. Liver function was preserved (p⩽ 0.05) after the rewarming period in hypothermic animals but showed no difference at the end of the observation period. In H&E staining, cell death was slightly increased hypothermic animals and caspase-3 staining displayed tendency towards more apoptosis in hypothermic group as well.

CONCLUSIONS

Induction of hypothermia could not significantly improve hepatic damage during the first 48 h following major trauma. Further studies focusing on multi-organ failure including a longer observation period are required to illuminate the impact of hypothermia on hepatic function in multiple trauma patients.

Pre-operative fluid bolus for improved haemodynamic stability during minor surgery: A prospectively randomized clinical trial

BACKGROUND

Haemodynamic instability during the induction of anaesthesia and surgery is common and may be related to hypovolaemia caused by pre-operative fasting or chronic diuretic therapy. The aim of our prospective, controlled, randomized study was to test the hypothesis that a predefined fluid bolus given prior to general anaesthesia for minor surgery would increase haemodynamic stability during anaesthetic induction.

METHODS

Two hundred and nineteen fairly healthy adult patients requiring minor surgery were enrolled. All received standard treatment, including a pulse contour analysing device for non-invasive measurement of cardiac index. Infusion therapy was started in all patients at induction. The intervention group (106 patients) was randomized to receive an additional fluid bolus of 8 mL/kg Ringer's acetate solution before the induction of anaesthesia. The primary endpoint was the incidence of haemodynamic instability, defined as a significant reduction of blood pressure or cardiac index during induction of anaesthesia.

RESULTS

The interventional group had a lesser incidence of haemodynamic instability during induction (41.5% vs 56.6%, P = .025). This group also had higher cardiac index, stroke volume index, systolic and mean blood pressure and a greater left ventricular end-diastolic area.

CONCLUSIONS

A fluid bolus prior to anaesthesia reduced the incidence of haemodynamic instability during induction of general anaesthesia. The total fluid volume was slightly greater in the intervention group compared to the control group (1370 ± 439 mL vs 1219 ± 483 mL, P = .007). We conclude that a defined fluid bolus can help stabilizing haemodynamics in patients undergoing general anaesthesia.

[Peripheral Regional Anesthesia Without Any Complications - a Dream Comes True?!]

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.

Effect of bupivacaine and adjuvant drugs for regional anesthesia on nerve tissue oximetry and nerve blood flow

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.

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.

Intraneural injection of a test dose of local anesthetic in peripheral nerves - does it induce histological changes in nerve tissue?

BACKGROUND & OBJECTIVES

Most anesthesiologists use the injection of a test dose of local anesthetic in order to evaluate the final needle tip position. Thus, the intraneural injection of a full dose can be avoided. The aim of this study was to analyze whether an intraneural injection of a test dose of bupivacaine could trigger histological changes.

METHODS

Intraneural injections under direct vision were performed in 40 brachial plexus nerves in seven anesthetized pigs. Tibial nerves served as positive and negative controls. Two milliliter of bupivacaine 0.5% was injected in three nerves on the left brachial plexus. For control of local anesthetic's toxicity Ringer's solution was applied intraneurally on the right side. After maintaining 48 h of general anesthesia, the nerves were resected. The specimens were processed for histological examination and assessed for inflammation (hematoxylin and eosin stain, CD68-immunohistochemistry) and myelin damage (Kluver-Barrera stain). The degree of nerve injury was rated on a scale from 0 (no injury) to 4 (severe injury).

RESULTS

Statistical analysis showed no significant differences between the bupivacaine group [median (interquartile range) 1 (1-1.5)] and the Ringer's solution group [1 (0.5-2) P = 0.772]. Mild myelin alteration was found in 12.5% of all specimens following intraneural injection, irrespective of the applied substance.

CONCLUSIONS

"In our experimental study, intraneural injection of 2 ml of bupivacaine or Ringer's solution showed comparable mild inflammation. Nevertheless, inflammation can only be prevented by strictly avoiding nerve perforation followed by intraneural injection, as mechanical nerve perforation is a key factor for evolving inflammation.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Phrenic palsy and analgesic quality of continuous supraclavicular vs. interscalene plexus blocks after shoulder surgery

BACKGROUND

Hemidiaphragmatic palsy is a common consequence of the interscalene brachial plexus block. It occurs less commonly with the supraclavicular approach. Register data suggest that the analgesic quality of a supraclavicular blockade is sufficient for arthroscopic shoulder surgery, although data on the post-operative analgesic effect are lacking.

METHODS

After approval by the ethics committee, patients having arthroscopic shoulder surgery under general anaesthesia were randomized to receive a continuous interscalene or supraclavicular blockade. Phrenic nerve function was evaluated through ultrasound examination of the diaphragm in combination with spirometry. Pain scores at rest and activity etc. were determined before catheter insertion, during observation in the post- anaesthesia care unit (PACU) and on post-operative day 1 (POD1). The initial application of 10 ml of ropivacaine 0.2% was followed by continuous application of 4 ml of ropivacaine 0.2%, plus a patient controlled analgesia (PCA) bolus of 4 ml/h.

RESULTS

One hundred and twenty patients were randomized, of which 114 data sets were analysed. Complete hemidiaphragmatic paresis occurred in 43% of the interscalene group vs. 24% in the supraclavicular group during PACU stay. Rates of dyspnoea and hoarseness were similar. Horner's syndrome occurred in 21% of the interscalene but only 3% of the supraclavicular group on POD1. Pain scores were comparable for pain at rest and during stress at each time point.

CONCLUSIONS

This trial showed a significantly greater incidence of phrenic nerve palsy of the interscalene group in PACU, but not on POD1. Post-operative analgesic quality was similar in both groups. Continuous supraclavicular blockade is a suitable alternative to the continuous interscalene technique.

Initial Resistance of Carina Anastomoses with Increasing Tensile Stress: An ex vivo Model Comparing Different Suture Techniques

BACKGROUND

After resection of the carina with a length of more than 4 cm, anastomoses often need to be performed under tension despite maximum mobilization. If the patient cannot be extubated, the anastomosis remains under continued stress. Anastomoses of the carina can be constructed using various suture techniques, including single interrupted sutures, back wall running but front wall single interrupted sutures, and complete running suture. This experimental study was designed to determine the most tensile stress-resistant anastomotic suture technique.

MATERIALS AND METHODS

Isolated preparations of tracheobronchial trees were recovered from freshly slaughtered pigs. Resection of the carina was carried out in preparation of the experiments. After blind randomization, anastomoses (n = 15 per group) between the distal trachea and the proximal left main bronchus were performed with PDS 4-0 employing three different suture techniques: (1) single interrupted sutures, (2) back wall running but front wall single interrupted sutures (= mixed technique), and (3) complete running suture. The anastomotic specimen was fixed onto a specially constructed device. The tracheal end was intubated with a tube (CH 8.0) and connected to a respirator. Different weights were attached to the distal end of the preparation via a clamp and guide rollers. Airtightness was investigated at the following tensile loads: 0, 500, 1,000 and 1,500 g. Intrabronchial pressure was increased in 5-mbar steps. In an underwater trial, we analyzed whether anastomoses were airtight at a maximum intrabronchial ventilation pressure of 70 mbar.

RESULTS

At an intrabronchial pressure of 25 mbar without tensile stress, all anastomoses were initially airtight. In tensionless anastomoses at 70 mbar, 100% of single interrupted and continuous sutures were airtight, as compared to 80% of sutures in mixed technique. At 70 mbar and tensile loads of 1,500 g, 80% of single interrupted sutures, 60% of sutures in mixed technique and 53% of the running sutures remained competent.

CONCLUSION

If tracheal anastomoses can be performed without tension, the suture technique is not important. With increased tension, anastomoses performed in single interrupted suture technique were clearly superior. Thus, in situations, where high tensile stress is to be expected, single interrupted sutures should be preferred.

Peripheral nerve blocks on the upper extremity: Technique of landmark-based and ultrasound-guided approaches

The German Society of Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin, DGAI) established an expert panel to develop preliminary recommendations for the application of peripheral nerve blocks on the upper extremity. The present recommendations state in different variations how ultrasound and/or electrical nerve stimulation guided nerve blocks should be performed. The description of each procedure is rather a recommendation than a guideline. The anaesthesiologist should select the variation of block which provides the highest grade of safety according to his individual opportunities. The first section comprises recommendations regarding dosages of local anaesthetics, general indications and contraindications for peripheral nerve blocks and informations about complications. In the following sections most common blocks techniques on the upper extremity are described.

Tunnelling of thoracic epidural catheters is associated with fewer catheter-related infections: a retrospective registry analysis

BACKGROUND

Catheter-related infections are a serious complication of continuous thoracic epidural analgesia. Tunnelling catheters subcutaneously may reduce infection risk. We thus tested the hypothesis that tunnelling of thoracic epidural catheters is associated with a lower risk of catheter-related infections.

METHODS

Twenty-two thousand, four hundred and eleven surgical patients with continuous thoracic epidural analgesia included in the German Network for Regional Anaesthesia registry between 2007 and 2014 were grouped by whether their catheters were tunnelled (n=12 870) or not (n=9541). Catheter-related infections in each group were compared with Student's unpaired t and χ(2) tests. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with logistic regression, adjusting for potential confounding factors, including age, ASA physical status score, use of catheter for ≥4 days, multiple skin puncture, hospital, and surgical department.

RESULTS

There were fewer catheter-related infections in patients with tunnelled catheters (4.5 vs 5.5%, P<0.001). Mild infections were also less common (4.0 vs 4.6%, P=0.009), as were moderate infections (0.4 vs 0.8%, P<0.001). After adjustment for potential confounding factors, tunnelling remained an independent prevention for any grade of infection (adjusted OR 0.51, 95% CI 0.42-0.61, P<0.001) and for mild infections (adjusted OR 0.54, 95% CI 0.43-0.66, P<0.001) and moderate and severe infections (adjusted OR 0.44, 95% CI 0.28-0.70, P=0.001).

CONCLUSION

Tunnelling was associated with a lower risk of thoracic epidural catheter-related infections.

Suture or Stapling Are Superior in Comparison to Bipolar Sealing for Closing the Bronchi

Background Every anatomical lung resection requires the airtight closure of at least one bronchus. In current clinical practice, these bronchi are sealed with sutures or staplers. This study investigated in an ex vivo pig model whether a new bipolar sealing device MARSEAL (KLS Martin, Tuttlingen, Germany) could be an alternative for this purpose. Methods Complete bronchial trees were prepared free from pig heart-lung blocks that were removed at a slaughterhouse. These preparations were taken to the laboratory, and main, lobar, and segmental bronchi were closed using sutures, staples, or bipolar sealing. Each trachea was then intubated and connected to a ventilating device. The initial airtight closure of the bronchus was first tested with lung-protective ventilation. After 15 minutes of ventilation, the inspiratory ventilation pressure was slowly increased and the burst pressure (in mbar) was recorded. Each group included 12 bronchus closures. Group mean burst pressures were compared using a nonparametric test (Mann-Whitney U test). The significance level was p < 0.05. Results The main bronchi closed both stapler magazines or sutures were all initially airtight during ventilation. The mean burst pressure was 60 ± 0 mbar for staplers and 57.92 ± 5.8 mbar for sutures. In contrast, 50% of main bronchi sealed with MARSEAL devices (5 or 10 mm) leaked air from the beginning. This was also noted in all lobar bronchi sealed with the MARSEAL 5-mm device and 80% of those sealed with the MARSEAL 10-mm device. The mean burst pressure of initially airtight lobar bronchi was 12.7 ± 7.25 mbar. In contrast, all segmental bronchi (mean width: 1.6 cm) were airtight when ventilated. Mean burst pressure was 14.64 ± 9.1 mbar with the MARSEAL 5-mm device and 29.64 ± 21.3 mbar with the MARSEAL 10-mm device. Histological investigation of the preparations (with hematoxylin and eosin staining) showed intact cartilaginous structures that were largely unaffected by bipolar coagulation. The airtight sealing of the segmental bronchi resulted from fusion of the peribronchial tissue and not the cartilage. Conclusion Bipolar sealing is an inappropriate tool for the closure of the bronchi in comparison to suture or stapling.

[Bipolar Sealing of Lung Veins with 5 mm and 10 mm Instruments - Bursting Pressures Measured in an Ex-Vivo Model]

BACKGROUND

In every anatomic lung resection, lung veins need to be sealed and divided. If open surgery is performed, veins are usually treated with ligatures. In minimally-invasive procedures a vascular stapler is used. Blood vessels can be securely closed with modern bipolar sealing technology. Since this method has rarely been used in lung veins, we carried out the present study on an ex-vivo model to test whether satisfactory bursting pressures can be achieved using 5 mm and 10 mm MARSEAL® sealing instruments.

MATERIAL AND METHODS

The experimental investigations were carried out on heart-lung preparations (including both lungs) from freshly-slaughtered pigs (weight: 199 lbs). After the lung veins were dissected, three groups were formed according to size: group 1: 1-7 mm, group 2: 8-10 mm and group 3: > 10 mm. Bipolar sealing was performed with a 5 mm or 10 mm MARSEAL® sealing device and the special SealSafe® G5 electric current. Vessels closed by simple ligation served as a control group. A pressure sensor was implanted into the unsealed end of the blood vessel. Air was pumped into the blood vessel and the bursting pressure - the pressure (in mbar) at which the vessel began to leak - was determined digitally. The mean bursting pressures were compared using the non-parametric Mann Whitney U test (the level of significance was p < 0.05).

RESULTS

In group 1 the mean bursting pressures for the 5 mm and 10 mm instruments were found to be 167.1 ± 38.7 mbar and 113.8 ± 23.3 mbar, respectively. Both were significantly inferior to the pressure of 178.8 ± 44.5 mbar achieved by the control group. In group 2 the bursting pressures were 122.7 ± 27.8 mbar with the 5 mm instrument and 93.5 ± 39.6 mbar with the 10 mm instrument. The mean bursting pressure for the control group was 180.7 ± 35.8.mbar. In group 3 the mean bursting pressures were 98.2 ± 28.8 mbar with the 5 mm instrument and 65.5 ± 19.7 mbar with the 10 mm instrument. All attempts to seal the entire left atrium failed.

CONCLUSION

In our ex-vivo model of lung veins, acceptable bursting pressures were achieved in blood vessels with a maximum diameter of 10 mm. Bipolar impedance-controlled sealing may create an adequate seal on pulmonary veins up to a diameter of 10 mm. The use of a 10 mm instrument has no advantage compared to a 5 mm instrument. Secure sealing of the left atrium is not possible.

[Glucocorticoids as an adjunct in peripheral regional anesthesia. Move to the "Holy Grail of perineural analgesia"?!]

BACKGROUND

The role of dexamethasone as an adjunct in peripheral nerve blockades is still unclear.

OBJECTIVES

This article reviews the actual knowledge and scientific evidence for dexamethasone as an adjunct in peripheral regional anesthesia. Moreover, it discusses the benefits of the systemic versus the perineural mode of application.

RESULTS

Dexamethasone prolongs sensible as well as motor blockades in peripheral nerve blocks when applied intravenously or perineurally. Regarding potentially local neurotoxicity, published patient data are not sufficient for final conclusions.

CONCLUSIONS

After reviewing the actual literature, the authors prefer a systemic application mode (intravenously) over a perineural route of administration of dexamethasone as an adjunct for peripheral nerve blocks. This is due to the better understanding of potential side effects of the drug when applied intravenously. Dexamethasone might be a useful drug adjunct to prolong peripheral single shot nerve blocks.

Risk evaluation for needle-nerve contact related to electrical nerve stimulation in a porcine model

BACKGROUND

For performing peripheral nerve blocks, the risk for needle-nerve contact (NNC) as an adverse event for low and high current thresholds has not yet been clearly defined when nerve stimulator guided techniques were applied. This experimental study aimed to investigate the risk of NNCs when applying stimulation currents between 0.1 and 2 mA (in increments of 0.1 mA).

METHODS

Brachial plexus nerves were exposed surgically in five anesthetized pigs. An insulated needle connected to a nerve stimulator was placed at 10 mm distance to the targeted nerves. Current intensity was adjusted according to randomization (0.1-2.0 mA, increments of 0.1 mA). The needle tip was advanced toward the nerve until a motor response was elicited. The frequencies of NNCs for each of the adjusted current intensities were noted. Risks of NNCs were calculated according to the analysis of 95% confidence intervals (95% CI).

RESULTS

We executed 2000 needle placements with stimulation currents ranging from 0.1 to 2.0 mA. The risks for NNC at low current intensities were 0.85 (95% CI, 0.77-0.91) for 0.3 mA and 0.5 (95% CI, 0.4-0.6) for 0.5 mA, respectively. For high current intensities, risks of 0.13 (95% CI, 0.07-0.21) for 0.9 mA and 0.01 (95% CI, 0-0.05) for 1.1 mA were calculated.

CONCLUSIONS

In this experimental animal study, a relevant reduction in the risk of NNCs could be observed when high current intensities (0.9-1.1 mA) were applied compared to low current intensities (0.3-0.5 mA).

Continuous adductor canal block versus continuous femoral nerve block after total knee arthroplasty for mobilisation capability and pain treatment: a randomised and blinded clinical trial

INTRODUCTION

Continuous femoral nerve blocks for total knee arthroplasty can cause motor weakness of the quadriceps muscle and thus prevent early mobilisation. Perioperative falls may result as an iatrogenic complication. In this randomised and blinded trial, we tested the hypothesis that a continuous adductor canal block is superior to continuous femoral nerve block regarding mobilisation ('timed up-and-go' test and other tests) after total knee arthroplasty under general anaesthesia.

METHODS

In our study, we included patients scheduled for unilateral knee arthroplasty under general anaesthesia into a blinded and randomised trial. Patients were allocated to a continuous adductor canal block (CACB) or a continuous femoral nerve block (CFNB) for three postoperative days (POD 1-3); with a bolus of 15 ml ropivacaine 0.375%, followed by continuous infusion of ropivacaine 0.2% and patient-controlled bolus administration. Both groups received an additional continuous sciatic nerve block as well as a multimodal systemic analgesic treatment. The primary outcome parameter was mobilisation capability, assessed by 'timed up-and-go' (TUG) test. Analgesic quality, need for opioid rescue and local anaesthetic consumption were also assessed.

RESULTS

Forty-two patients were included and analysed (21 patients per group). No significant difference was noted in respect to mobilisation at POD 3 (TUG [s]: CACB 45, CFNB 51). It is worth saying that pain scores (numeric rating scale, NRS) were similar in both groups at POD 3 {rest [median (interquartile range)]: CACB 0 (0-3), CFNB 1 (0-3); stress: CACB 4 (2-5), CFNB 3 (2-4)}.

CONCLUSIONS

Concerning the mobilisation capability, we did not actually observe a superior effect of CACB compared with CFNB technique in our patients following total knee arthroplasty. Moreover, no difference was observed concerning analgesia quality.

A porcine polytrauma model with two different degrees of hemorrhagic shock: outcome related to trauma within the first 48 h

BACKGROUND

An animal polytrauma model was developed, including trunk and extremity injuries combined with hemorrhagic shock and a prolonged post-traumatic phase. This could be useful for the assessment of different therapeutic approaches during intensive care therapy.

METHODS

A standardized polytrauma including lung contusion, liver laceration and lower leg fracture was applied in 25 pigs. They underwent controlled haemorrhage either with a blood volume loss of 45 % and a median arterial pressure (MAP) <30 mmHg/90 min (group L, n = 15) or a 50 % blood loss of and an MAP <25 mmHg/120 min (group H, n = 10). Five non-traumatized pigs served as a control (group C). Subsequently, intensive care treatment was given for an observational period of 48 h.

RESULTS

Both trauma groups showed signs of shock and organ injury (heart rate, MAP and lactate). The frequency of cardiopulmonary resuscitation (CPR) and lung injury was directly related to the severity of the haemorrhagic shock (CPR-group L: 4 of 15 pigs, group H: 4 of 10 pigs; Respiratory failure-group L: 3 of 13, group H: 3 of 9. There was no difference in mortality between trauma groups.

CONCLUSION

The present data suggest that our model reflects the mortality and organ failure of polytrauma in humans during shock and the intensive care period. This suggests that the experimental protocol could be useful for the assessment of therapeutic approaches during the post-traumatic period.

Obesity in regional anesthesia--a risk factor for peripheral catheter-related infections

BACKGROUND

Obesity is believed to increase the risk of surgical site infections and possibly increase the risk of catheter-related infections in regional anesthesia. We, therefore, analyzed the influence of obesity on catheter-related infections defined within a national registry for regional anesthesia.

METHODS

The German Network for Regional Anesthesia database with 25 participating clinical centers was analyzed between 2007 and 2012. Exactly, 28,249 cases (13,239 peripheral nerve and 15,010 neuraxial blocks) of patients ≥ 14 years were grouped in I: underweight (BMI 13.2-18.49 kg/m(2) , n = 597), II: normal weight (BMI 18.5-24.9 kg/m(2) , n = 9272), III: overweight (BMI 25.0-29.9 kg/m(2) , n = 10,632), and IV: obese (BMI 30.0-70.3 kg/m(2) , n = 7,744). The analysis focused on peripheral and neuraxial catheter-related infections. Differences between the groups were tested with non-parametric ANOVA and chi-square (P < 0.05). Binary logistic regression was used to compare obese, overweight, or underweight patients with normal weight patients. Odds ratios (OR and 95% confidence interval) were calculated and adjusted for potential confounders.

RESULTS

Confounders with significant influence on the risk for catheter-related infections were gender, age, ASA score, diabetes, preoperative infection, multiple skin puncture, and prolonged catheter use. The incidence (normal weight: 2.1%, obese: 3.6%; P < 0.001) and the risk of peripheral catheter-related infection was increased in obese compared to normal weight patients [adjusted OR: 1.69 (1.25-2.28); P < 0.001]. In neuraxial sites, the incidence of catheter-related infections differed significantly between normal weight and obese patients (normal weight: 3.2%, obese: 2.3%; P = 0.01), whereas the risk was comparable [adjusted OR: 0.95 (0.71-1.28); P = 0.92].

CONCLUSION

This retrospective cohort study suggests that obesity is an independent risk factor for peripheral, but not neuraxial, catheter-related infections.

Separation of stimulating catheters for continuous peripheral regional anesthesia during their removal - two case reports and a critical appraisal of the use of steel-coil containing stimulating catheters

Purpose

Stimulating catheters are widely used for continuous peripheral nerve block techniques in regional anesthesia. The incidence of reported complications is somewhat similar to that for non-stimulating catheters. However, as many stimulating catheters contain a coiled steel wire for optimal stimulation, they may cause specific complications.

Clinical features

In this report, we present two cases of complicated removals of stimulating catheters. During both removals, a part of the metal wire was left “decoiled” next to the supraclavicular and interscalene plexus, respectively. The strategies used to determine steel wire localization and a description of the successful removal of these steel wires are included in this report.

Conclusion

Catheter separation and problems with residual metal wire components of stimulating catheters seem to be a rare but specific problem during removal. Anesthesiologists should strictly avoid catheter shearing during insertion, adhere to the manufacturer’s instructions, and take care during catheter removal. Manufacturers should focus on technical solutions to avoid rare but relevant complications such as catheter tip decoiling and separation of stimulating catheters during removal.

Focused intraoperative transthoracic echocardiography by anesthesiologists: a feasibility study

BACKGROUND

Focused transthoracic echocardiography (TTE) is frequently used perioperatively for hemodynamic monitoring and diagnosis of cardiovascular instability, but less commonly intraoperatively.

METHODS

To evaluate the feasibility of intraoperative TTE, we enrolled 222 anesthetised patients from August to November 2012 into a prospective observational study. 162 patients underwent TTE examination according to the Focused Assessed Transthoracic Echocardiography (FATE) protocol after positioning and draping for surgery. Sixty additional hemodynamically unstable subjects were examined during anesthesia and surgery. The imaging quality of four FATE views was rated on a scale from 1 (impossible) to 5 (perfect). TTE was assessed as applicable, if at least two of the four basic FATE views were graded 4 or 5, or three views were assessed as grade 3.

RESULTS

Imaging quality was unacceptable in 20 patients, resulting in a feasibility rate of 91% (97.5%-CI 0.86-1, P=0.01). TTE was feasible in hemodynamically unstable subjects (91.7%; 97.5%-CI 0.82-1.0), in orthopedic and trauma patients (>95% respectively, [97.5%-CI 0.83-1]) and in abdominal surgery (78%).

CONCLUSION

TTE can be applied in the operating theatre during surgery, although its use during abdominal surgery is somewhat limited.

[Regional anaesthesia in injuries of the upper extremity]

Regional anaesthesia has significant advantages compared to general anaesthesia with an opiate-based postoperative analgesia in injuries of the upper extremity. Severe pain may be considered a risk factor for the development of chronic postoperative pain syndromes in adults and children. Depending on the anticipated postoperative pain level, a catheter procedure should be used. Fractures of the upper extremity are common and may also be associated with seemingly minor injuries with a high postoperative pain level. Nerve damage can be caused mainly by traumatic fractures, or iatrogenically during surgical procedures. Reduced possible neurological evaluability should not prevent the excellent pain control which regional anesthesia can provide. Since the brachial plexus is predominantly responsible for the sensory innervation of the entire upper extremity, therefore all known block techniques in regional anaesthesia apply. Since the introduction of ultrasound in regional anaesthesia (USGRA), older methods like the supraclavicular approach, which were previously banned due to high complication rates, are now being rediscovered. Both new and old blockade methods are much more effective and safe with ultrasound support because of the rapid visualization of the anatomy and needle.

[Regional anaesthesia in patients with lower limb injury]

Almost all surgical procedures following injury can be provided in peripheral regional anaesthesia or spinal anaesthesia - under consideration of specific contraindications. The majority of injuries at the lower limb are associated with severe pain and immobilization during the postoperative phase. Moreover, opioids are often required which are related to nausea, vomiting and impairment of vigilance. For avoidance of those side effects, regional anaesthesia techniques should be considered as a more effective approach with a better profile of side effects. Hip and proximal femur fractures are more frequent in elder patients with a corresponding high morbidity. Therefore anaesthesia is challenging in those patients. Even injuries of the long bones - like the femur and the tibia - are causing severe pain, therefore an appropriate concept for acute pain therapy is required. Moreover, for injuries with affection of bony joint-structures (i. e. knee, ankle, calcaneus) and marked soft-tissue injuries continuous regional anaesthesia techniques could provide advantages during acute pain therapy.

Impact of haemorrhagic shock intensity on the dynamic of alarmins release in porcine poly-trauma animal model

PURPOSE

Traumatic insults result in an altered inflammatory response, in which alarmins release has a central role. The impact of haemorrhagic shock intensity on the long-term kinetics of alarmins is not yet fully elucidated. We investigated these aspects in a combined trauma (chest, abdominal, and extremities injury) porcine model with different severities and durations of haemorrhagic shock.

METHODS

After induction of combined trauma (tibia fracture, lung contusion, and liver laceration), haemorrhagic shock was induced at different intensities: moderate haemorrhage (MH; n = 15): mean arterial pressure (MAP) <30 ± 5 mmHg [maximum loss of total blood volume (TBVmax): 45 %] for 90 min, and severe haemorrhage (SH; n = 10): MAP <25 ± 5 mmHg (TBVmax 50 %) for 120 min. Resuscitation was performed using a standardized crystalloid infusion protocol. Animals were mechanically ventilated and underwent ICU-monitoring for 48 h (MH) and 48.5 h (SH). Blood samples were collected over the clinical time course, and systemic levels of serum alarmins [High-Mobility Group Protein B-1 (HMGB-1) and Heat Shock Protein 70 (HSP70)] were measured using an ELISA kit.

RESULTS

Heart rate, systemic blood pressure, lactate, and base excess were significantly altered as a function of haemorrhagic shock in both trauma groups (MH and SH). Systemic HMGB-1 levels were significantly elevated in both trauma groups when compared to the sham group. Haemorrhagic shock severity and duration were positively correlated with HMGB-1 levels and compared to baseline values, concentrations remained significantly increased in SH when compared to MH. On the other hand, we observed a significant decrease in the systemic HSP70 levels of trauma groups (MH, and SH) when compared to the sham group, which was significantly decreased compared to baseline values in SH over the entire time course.

CONCLUSION

Our data show that haemorrhagic shock duration and severity affect the systemic levels of HMGB-1 and HSP70. This early alarmins release after trauma can be used to guide the treatment strategies (e.g. surgical procedures) of polytrauma patients.

[Seeing more : Technical innovations in regional anesthesia]

Visualization and verification are key factors since the implementation of ultrasound-guided regional anesthesia. This article reviews and discusses newer technical innovations in regional anesthesia with regard to optimization of needle guidance, improvements in needle visibility, technical improvements in ultrasound techniques and innovative technologies in regional anesthesia. Clinically available applications are presented as well as experimental tools and techniques with a potential for clinical implementation in the future. Mechanical needle guides are used to improve alignment of needle axis and ultrasound beam axis. Compound imaging technology improves needle visibility in steep needle insertion angles and is already implemented in daily clinical practice. Sonoelastography improves tissue discrimination and detection of small amounts of fluids. Benefits of 3D and 4D ultrasound in regional anesthesia are discussed as well as experimental tools for tissue discrimination, such as optical reflection spectrophotometry.

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

BACKGROUND

The 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.

DESCRIPTION

Hundred 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.

CONCLUSIONS

Given the hemodynamic stability and lower incidence of intraoperative hypotension observed, levobupivacaine could be the agent of choice for subarachnoid anesthesia in elderly patients.

Bipolar impedance-controlled sealing of the pulmonary artery with SealSafe G3 electric current: determination of bursting pressures in an ex vivo model

BACKGROUND

In every anatomic lung resection operation, the pulmonary artery itself or its branches must be sealed. This involves either stapling or ligating the vessels. Based on the positive results with the bipolar vessel sealing ≤7 mm in abdominal surgery the present study aimed to evaluate burst pressures of the pulmonary artery after sealing with the sealing instrument SealSafe G3 (Gebrüder Martin & CoKG, Tuttlingen, Germany).

MATERIAL AND METHODS

The whole pulmonary artery above the pulmonary valve was exposed up to the periphery of the left lung in freshly removed pig heart-lung blocks. A pressure-measuring cylinder was then implanted in the prepared vessel on the side at the main trunk of the pulmonary artery to determine the pressure in the vessel. After either ligation or bipolar sealing of the pulmonary artery, the pneumatic burst pressure (millimeters of mercury) was determined in a water bath. Three groups (n = 12 for each seal type) with different vessel diameters were examined: group 1: 0-6 mm, group 2: 7-12 mm, and group 3: >12 mm. In all cases, vessel sealing was performed with a MARSEAL 5 instrument (Gebrüder Martin & Co KG, Tuttlingen, Germany) and the SealSafe G3 current. The mean burst pressures of the individual groups (ligature and bipolar sealing) were compared using two-tailed, nonparametric Mann-Whitney U test. Significance was defined as P < 0.05.

RESULTS

The mean burst pressures in group 1 were measured by 340 ± 13.4 mm Hg with ligature and 205 ± 44.4 mm Hg with bipolar sealing (P < 0.001). In group 2, the mean values obtained were 270 ± 28.2 mm Hg for ligature and 162 ± 36.0 mm Hg for bipolar sealing (P < 0.001). In group 3, the mean burst pressures for bipolar sealing were only 52.1 ± 15.1 mm Hg, whereas those for ligated vessels were 253 ± 46.9 mm Hg (P < 0.001). For this size of vessel the burst pressure was also determined after stapling. The mean value in this case was 230 ± 21.8 mm Hg.

CONCLUSIONS

In all groups, the mean burst pressures after bipolar sealing were significantly lower than those achieved with ligation, but they were sufficient for a save closure of the pulmonary artery with diameters up to 12 mm.

[Localization of peripheral nerves. Success and safety with electrical nerve stimulation]

Peripheral electrical nerve stimulation is one of the standard applications in peripheral regional anesthesia in addition to the ultrasound technique. Among other findings, the visualization of needle and nerve during ultrasound-guided blockade caused a change in clinical practice of peripheral nerve stimulation in the last decade. In the present article old and new aspects of principles and clinical practice of the nerve stimulation technique are presented and summarized in a total clinical concept in order to achieve safe and successful peripheral regional anesthesia using electrical peripheral nerve stimulation.