Ultraschallgesteuerte periphere Regionalanästhesie

Cross-sectional area of the median nerve after intraneural vs perineural low volume administration

INTRODUCTION

To recognise the relationship between the needle tip and the median nerve during peripheral nerve block is of interest to avoid neural damage. However, signs of intraneural injection are not clearly established. The aim of this study was to define the changes observed in the peripheral nerve after the intraneural or perineural administration of 1ml of solution.

MATERIAL AND METHODS

Ultrasound guided median nerve blocks were performed in the forearm of 10 fresh cadavers on 60 occasions (3 per forearm). They were randomised into the intraneural (n=30) or perineural (n=30) location of the needle tip, after the consensus of location by 7 specialists. After 1ml of solution was injected an evaluation was made of the changes in the cross-sectional area of the nerve, as well as the displacement along the nerve.

RESULTS

The cross-sectional area of the median nerve was increased in both groups, however, the increase was significantly higher in the intraneural group (perineural 0.007±0.013cm2 vs. intraneural 0.032±0.021cm2, P<.0001). An increase of more than 27% of the area ensures an intraneural injection in the median nerve according to the ROC curve analysis. Both proximal and distal diffusion were observed more frequently in the intraneural group (proximal: 86% vs 14%, P<.0001, Distal: 43% vs 4%, P<.0001).

CONCLUSIONS

Based on this experimental study, it is concluded that the injection of a small volume (1ml) allows to discriminate the disposition of the intraneural vs perineural needle in a high percentage of cases. Therefore, it is suggested that this "dose test" should be considered in the safety algorithms if it is required to reduce the incidence of intraneural injection.

Which Ultrasound-Guided Sciatic Nerve Block Strategy Works Faster? Prebifurcation or Separate Tibial-Peroneal Nerve Block? A Randomized Clinical Trial

Background

Peripheral nerve block is an accepted method in lower limb surgeries regarding its convenience and good tolerance by the patients. Quick performance and fast sensory and motor block are highly demanded in this method. The aim of the present study was to compare 2 different methods of sciatic and tibial-peroneal nerve block in lower limb surgeries in terms of block onset.

Methods

In this clinical trial, 52 candidates for elective lower limb surgery were randomly divided into 2 groups: sciatic nerve block before bifurcation (SG; n = 27) and separate tibial-peroneal nerve block (TPG; n = 25) under ultrasound plus nerve stimulator guidance. The mean duration of block performance, as well as complete sensory and motor block, was recorded and compared between the groups.

Results

The mean duration of complete sensory block in the SG and TPG groups was 35.4 ± 4.1 and 24.9 ± 4.2 minutes, respectively, which was significantly lower in the TPG group (P = 0.001). The mean duration of complete motor block in the SG and TPG groups was 63.3 ± 4.4 and 48.4 ± 4.6 minutes, respectively, which was significantly lower in the TPG group (P = 0.001). No nerve injuries, paresthesia, or other possible side effects were reported in patients.

Conclusions

According to the present study, it seems that TPG shows a faster sensory and motor block than SG.

[Anesthesia for medical students : A brief guide to practical anesthesia in adults with a web-based video illustration]

In Germany, Austria and Switzerland, anesthesiologists are the second largest group of physicians in hospitals, but this does not correspond to the amount of anesthesiology teaching that medical students receive in medical schools. Accordingly, the chances of medical students recognizing anesthesiology as a promising personal professional career are smaller than in other disciplines with large teaching components. Subsequent difficulties to recruit anesthesiology residents are likely, although many reasons support anesthesiology as a professional career.Traditional strategies to teach medical students in anesthesiology in medical school consist of airway management or cardiopulmonary resuscitation attempts in manikins. Anesthesiology is a complex interaction consisting of anatomy, physiology, pharmacology, clinical evaluation, experience, knowledge, and manual skills. While some medical schools offer teaching in high fidelity simulators, clinical teaching in the operating room is often limited. When medical students opt for a clinical rotation in anesthesiology, there is a chance to demonstrate the fascinating world of anesthesiology, but this chance has to be utilized carefully by anesthesiologists, as young talents have to be discovered, supported, and challenged.We have put together a short guide for medical students for a clinical rotation in anesthesiology in adults in order to generate basic knowledge and interest in anesthesiology as well as a sense of achievement. Basic knowledge about premedication, induction, maintenance and strategies for anesthesia is discussed. Further, the most important anesthesia drugs are discussed and manual skills, such as intravenous cannulation, mask ventilation, intubation, and regional anesthesia are featured with QR-code based video illustrations on a smartphone or personal computer. We did not discuss possible local mannerism and special patient groups (e. g., children, special medical history), local guidelines, or standard operating procedures.Medical students can be inspired by anesthesiology when not simply told about the tools of the trade and strategies, but instead by gaining knowledge and clinical skills that render a sense of achievement, likely during a clinical rotation into anesthesiology. A short theoretical instruction of anesthesiology enables rapid and targeted orientation even before a clinical rotation. Whether this subsequently results in a higher recruiting chance is currently unknown.

Regionale Nervenblockaden

Periphere Nervenblockaden werden hervorgerufen durch die Injektion eines Lokalanästhetikums in die unmittelbare Nähe von Einzelnerven, Nervenstämmen oder Nervengeflechten. Das Lokalanästhetikum diffundiert zur Innenseite des Nervs und blockiert vorübergehend die spannungsabhängigen Natriumkanäle. Hierdurch entsteht eine lokal begrenzte Anästhesie, die sich eng auf das für eine Operation erforderliche Gebiet beschränkt. Die Auswirkungen auf die übrigen Körperfunktionen sind gering, v. a. werden die Atmung und Herz-Kreislauf-Funktion nicht beeinträchtigt. Die Nerven werden mit Elektrostimulation oder Ultraschall aufgesucht; Parästhesien sollten hierfür nicht ausgelöst werden. Komplikationen durch periphere Blockaden sind sehr selten. Nervenschäden, Gefäßpunktionen und Hämatome, Lokalanästhetikaintoxikation und Infektionen treten v. a. bei Kathetertechniken auf.