Roderick J. Finlayson

Minimum effective volume of lidocaine for ultrasound-guided infraclavicular block.

Background: The aim of this study was to determine the minimum effective volume of lidocaine 1.5% with epinephrine 5 &mgr;g/mL in 90% of patients (MEV90) for single-injection ultrasound-guided infraclavicular block (ICB). Methods: Using an in-plane technique, a single-injection ultrasound-guided ICB was performed: a 17-gauge, 8-cm Tuohy needle was advanced until the tip was located dorsal to the axillary artery. Volume assignment was carried out using a biased coin design up-and-down sequential method, where the volume of local anesthetic administered to each patient depended on the response of the previous one. In case of failure, the next subject received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous patient had a successful block, the next subject was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 − b = 0.89. Lidocaine 1.5% with epinephrine 5 &mgr;g/mL was used in all subjects. Success was defined, at 30 mins, as a minimal score of 14 of 16 points using a composite scale encompassing sensory and motor block. Patients undergoing surgery of the elbow, forearm, wrist, or hand were prospectively enrolled until 45 successful blocks were obtained. Results: Fifty-five patients were included in the study. Using isotonic regression and bootstrap confidence interval (CI), the MEV90 for single-injection ultrasound-guided ICB was estimated to be 35 mL (95% CI, 30-37.5 mL). The probability of a successful response at 35 mL was estimated to be 0.91 (95% CI, 0.8-1.0). All patients with a minimal composite score of 14 points at 30 mins achieved surgical anesthesia intraoperatively. Conclusions: For single-injection ultrasound-guided ICB, the MEV90 of lidocaine 1.5% with epinephrine 5 &mgr;g/mL is 35 mL. Further dose-finding studies are required for other concentrations of lidocaine, other local anesthetic agents as well as techniques involving multiple injections, a more medial approach to ICB, or precise location of all 3 cords of the brachial plexus.

A review of approaches and techniques for lower extremity nerve blocks

PurposeThe purpose of this narrative review is to summarize the evidence derived from randomized controlled trials (RCTs) regarding approaches and techniques for lower extremity nerve blocks.SourceUsing the MEDLINE (January 1966 to April 2007) and EMBASE (January 1980 to April 2007) databases, medical subject heading (MeSH) terms “lumbosacral plexus”, “femoral nerve”, “obturator nerve”, “saphenous nerve”, “sciatic nerve”, “peroneal nerve” and “tibial nerve” were searched and combined with the MESH term “nerve block“ using the operator “and”· Keywords “lumbar plexus”, “psoas compartment”, “psoas sheath”, “sacral plexus”, “fascia iliaca”, “three-in-one”, “3-in-1 ”, “lateral femoral cutaneous”, “posterior femoral cutaneous”, “ankle” and “ankle block” were also queried and combined with the MESH term “nerve block”. The search was limited to RCTs involving human subjects and published in the English language. Forty-six RCTs were identified.Principal findingsCompared to its anterior counterpart (3-in-I block), the posterior approach to the lumbar plexus is more reliable when anesthesia of the obturator nerve is required. The fascia iliaca compartment block may also represent a better alternative than the 3-in-1 block because of improved efficacy and efficiency (quicker performance time, lower cost). For blockade of the sciatic nerve, the classic transgluteal approach constitutes a reliable method. Due to a potentially shorter time for sciatic nerve electrolocation and catheter placement than for the transgluteal approach, the subgluteal approach should also be considered. Compared to electrolocation of the peroneal nerve, electrostimulation of the tibial nerve may offer a higher success rate especially with the transgluteal and lateral popliteal approaches. Furthermore, when performing sciatic and femoral blocks with low volumes of local anesthetics, a multiple-injection technique should be used.ConclusionsPublished reports of RCTs provide evidence to formulate limited recommendations regarding optimal approaches and techniques for lower limb anesthesia. Further well-designed and meticulously executed RCTs are warranted, particularly in light of new techniques involving ultrasonographic guidance.RésuméObjectifL’objectif de cet examen narratif est de résumer les données probantes dérivées d’études randomisées contrôlées (ERC) concernant les approches et techniques pour les blocs nerveux du membre inférieur.SourceA l’aide des bases de données MEDLINE (janvier 1966 à avril 2007) et EMBASE (janvier 1980 à avril 2007), les termes MeSH (vedette-matière médicale) « lumbosacral plexus », « femoral nerve », « obturator nerve », « saphenous nerve », « sciatic nerve », « peroneal nerve » et « tibial nerve » ont été recherchés et combinés au terme MeSH « nerve block » à l’aide de l’opérateur « and ». Les mots clés « lumbar plexus », « psoas compartment », « psoas sheath », « sacral plexus », « fascia iliaca », « three-in-one », «3-in-1», «lateral femoral cutaneous», «posterior femoral cutaneous », « ankle » et « ankle block » ont également été recherchés et combinés au terme MeSH « nerve block ». La recherche a été limitée aux ERC impliquant des sujets humains et publiées en langue anglaise. Quarante-six ERC ont été identifiées.Constatations principalesPar rapport à son équivalent antérieur (bloc 3-en-1), l’approche postérieure du plexus lombaire est plus fiable quand une anesthésie du nerf obturateur est requise. Le bloc du compartiment de l’aponévrose iliaque pourrait également représenter une meilleure alternative que le bloc 3-en-1 à cause d’une efficacité et d’une efficience améliorées (temps de performance plus court, coût moindre). Pour un bloc du nerf sciatique, l’approche transglutéale constitue une méthode fiable. En raison d’un temps potentiellement plus court pour l’électrolocation du nerf sciatique et le positionnement du cathéter que par la voie transglutéale, l’approche subglutéale devrait également être prise en considération. Par rapport à l’électrolocation du nerf péronier, l’électrostimulation du nerftibial pourrait offrir un taux de réussite plus élevé, particulièrement avec les abords transglutéal et latéral poplité. De plus, lors de la mise en place de blocs sciatique ou fémoral avec de petits volumes d’anesthésiques locaux, une technique d’injection multiple devrait être utilisée.ConclusionLes comptes rendus publiés d’ERC fournissent des données probantes qui permettent de formuler des recommandations limitées en ce qui concerne les approches et techniques optimales pour l’anesthésie du membre inférieur. Des ERC bien conçues et exécutées avec soin sont requises, particulièrement à la lumière de nouvelles techniques d’écho-guidage.

Use of Stellate Ganglion Block to Salvage an Ischemic Hand Caused by the Extravasation of Vasopressors

Objective This case report describes the successful use of early stellate ganglion block to salvage an acutely ischemic hand caused by the extravasation of vasopressors. Case Report A young man with a gunshot wound to the right inguinal area was brought to the operating room for surgical hemostasis and exploration. After discovery that the central line had been inserted in the proximity of the area of injury (right femoral vein), the vasopressor infusions were changed to a 14-gauge intravenous line inserted in the dorsum of the right hand. When the intravenous line became infiltrated, the hand was found to be swollen, cold, and underperfused. A right stellate ganglion block was immediately performed to overcome the intense peripheral vasoconstriction and, thus, re-establish circulation to the hand. Conclusions Stellate ganglion block may prove to be an early measure in the treatment of upper-extremity ischemia caused by vasopressor extravasation.