Peter Hebbard

Background Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks. Methods We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as ≥75% agreement and weak consensus as 50%–74% agreement. Results A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research. Conclusions We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.

This report reviews the topographical and functional anatomy relevant for assessing whether or not the obturator nerve (ON) can be anesthetized using a fascia iliaca compartment (FIC) block. The ON does not cross the FIC. This means that the ON would only be blocked by an FIC block if the injectate spreads to the ON outside of the FIC. Such a phenomena would require the creation of one or more artificial passageways to the ON in the retro-psoas compartment or the retroperitoneal compartment by disrupting the normal anatomical integrity of the FI. Due to this requirement for an artificial pathway, an FIC block probably does not block the ON.

We report 166 microinvasive ultrasound‐guided carpal tunnel releases using the MICROi‐Blade (Summit Medical Products, Inc, Sandy, UT), a needle‐based tool for cutting under ultrasound guidance. The 6‐month follow‐up of the first 21 cases, including 5 bilateral releases, showed a progressive reduction in median pain scores, Boston Carpal Tunnel Questionnaire (BCTQ) Symptom Severity Scale scores, and BCTQ Functional Status Scale scores. The median return to work was 7 days. The 3‐month follow‐up of 62 subsequent cases showed similar improvement in the BCTQ scores and return to work. There were no complications. This report supports the effectiveness of the technique.

Ultrasound (US)‐guided microinvasive procedures are defined as those performed via needles without notable scarring. Ten cadaver hands underwent US‐guided microinvasive carpal tunnel release using a novel needle‐based tool, the micro i‐Blade (Summit Medical Products, Inc, Sandy, UT). A US‐imaged landmark, the inflexion point of the ligaments distal to the hook of the hamate, was used to position the distal extent of the cut. The transverse carpal ligament was successfully released in all hands without damage to nerves or arteries. In 3 specimens, the fascia between the thenar and hypothenar muscles was partly preserved, whereas the palmar aponeurosis was partly cut in 1 specimen. The micro i‐Blade with the cutting knife retracted was also useful as a probe palpated through the palm of the cadaver hand, to test the release of the transverse carpal ligament and to guide the procedure.

Summary: Emergency catheter cricothyroidotomy often fails. Case reports have concentrated on kinking and displacement of the catheter as the major causes. We investigated catheter tip penetration of the trachea. Using insertion angles of 90°, 75°, 60°, 45° and 30° we advanced 14 G intravenous catheters into fresh isolated sheep tracheas during high pressure oxygen insufflation. At all angles, the catheter tip became blocked by pushing into the mucosa with submucosal gas injection on one or more attempts. Full thickness rupture with extratracheal gas also occurred on insertions at 90° and 60°. We then tested a Luer‐mounted prototype wire stylet which remains in situ during insufflation. Using the same methodology, the stylet was able to be placed and prevented blockage at all angles of insertion. Mucosal trauma and submucosal gas injection occurred on insertions at 90° and 75°. Our results should guide further stylet design.

Summary: Existing descriptions of ultrasound‐guided fascia iliaca block focus on injection of local anaesthetic inferior to the inguinal ligament, relying on supra‐inguinal spread to block the lateral femoral cutaneous nerve in the iliac fossa. In this study, we explored injectate spread and nerve involvement in a cadaveric dye‐injection model, using a supra‐inguinal ultrasound‐guided technique that places local anaesthetic directly into the iliac fossa. Bilateral injections of 20 ml 0.25% aniline blue dye were made in six unembalmed cadavers. The femoral nerve was stained by the dye in all twelve injections. The lateral femoral cutaneous nerve was stained bilaterally in five cadavers, but the nerve was absent on both sides in the sixth cadaver. The ilio‐inguinal nerve passed into the iliac fossa over the iliacus muscle in eight of the hemi‐pelvi and was stained in seven of these occasions. We have performed more than 150 blocks in patients using this approach without complications. Injection using this technique in cadavers leads to extensive fluid spread throughout the iliac fossa. In patients this approach may allow a lower volume block of the femoral nerve and lateral femoral cutaneous nerve while still injecting at a distance from the femoral nerve.

Background: Recently, ultrasound-guided transversus abdominis plane blockade for abdominal wall analgesia has been described, and it involves injection of local anesthetic into the transversus abdominis plane. The posterior approach involves injection of local anesthetic in the lateral abdominal wall between the costal margin and the iliac crest and is suitable for postoperative analgesia after surgery below the umbilicus. The subcostal approach is suitable after abdominal surgery in the periumbilical region. The subcostal block can be modified, and the needle can be introduced along the oblique subcostal line from the xyphoid process toward the anterior part of the iliac crest. Objective: The purpose of this brief technical report was to describe in detail the anatomy and the technique of continuous oblique subcostal blockade. The goal of this approach was to produce a wider sensory blockade suitable for analgesia after surgery both superior and inferior to the umbilicus. Conclusions: A catheter can be placed along the oblique subcostal line in the transversus abdominis plane for continuous infusion of local anesthetic. Multimodal analgesia and intravenous opioid are used in addition because visceral pain is not blocked. Continuous oblique subcostal transversus abdominis plane block is a new technique and requires both a detailed knowledge of sonographic anatomy and technical skill for it to be successful.