Anatomical evaluation of the extent of spread in the erector spinae plane block: a cadaveric study.

PURPOSE: The erector spinae plane (ESP) block is an interfascial analgesic technique first described as an alternative for pain control at the thoracic level. The objective of this observational study was to determine the anatomical spread of dye following a T7 ESP block in a cadaveric model. METHODS: An ultrasound-guided ESP block was performed in four fresh human cadavers using an in-plane approach with a linear probe in a longitudinal orientation and a puncture in a craniocaudal direction. Twenty millilitres of an iodinated contrast/methylene blue solution was injected deep to the erector spinae muscle at the distal end of the T7 transverse process bilaterally in two of the specimens, and unilaterally in the other two (six ESP blocks in total). Subsequently, the specimens were subjected to a multi-slice computed tomography (CT) scan with three-dimensional reconstruction. Two of the specimens were dissected to evaluate the distribution of the contrast solution, and a sectional study was performed in the other two. RESULTS: In the six samples, evaluated by CT scan and anatomical dissection, a craniocaudal spread of the dye was observed in the dorsal region from T1-T11 with lateral extension towards the costotransverse region. No diffusion of contrast solution or dye to the anterior region (paravertebral space) was observed by CT scan or dissection. CONCLUSIONS: The results suggest that the ESP block reaches a wide range of the posterior rami of spinal nerves without diffusion into the paravertebral space or involvement of the anterior rami.

RéSUMé: OBJECTIF: Le bloc du plan des muscles érecteurs du rachis (ESP) est une technique analgésique interfasciale qui avait d'abord été décrite comme une alternative pour contrôler la douleur au niveau thoracique. L'objectif de cette étude observationnelle était de déterminer la propagation anatomique d'un colorant après la réalisation d'un bloc ESP au niveau T7 dans un modèle cadavérique. MéTHODE: Un bloc ESP a été réalisé sous échoguidage sur quatre cadavres humains frais en utilisant une approche dans le plan avec une sonde linéaire en orientation longitudinale et une ponction en direction cranio-caudale. Vingt millilitres d'une solution de contraste iodée / bleu de méthylène ont été injectés postérieurement aux muscles érecteurs du rachis à l'extrémité distale de l'apophyse transverse T7, bilatéralement dans deux des spécimens et unilatéralement dans les deux autres (soit six blocs ESP au total). Par la suite, les spécimens ont été soumis à une tomodensitométrie multicoupe avec reconstruction en 3D. Deux des spécimens ont été disséqués afin d'évaluer la distribution de la solution de contraste, et une étude sectionnelle a été réalisée sur les deux autres spécimens. RéSULTATS: Dans les six échantillons évalués par tomodensitométrie et dissection anatomique, une propagation cranio-caudale du colorant a été observée dans la région dorsale de T1­T11 avec une extension latérale vers la région costo-transverse. La tomodensitométrie et la dissection n'ont révélé aucune propagation de la solution de contraste ou du colorant à la région antérieure (espace paravertébral). CONCLUSION: Ces résultats suggèrent que le bloc ESP atteint de nombreux rameaux postérieurs des nerfs rachidiens sans diffusion dans l'espace paravertébral ou atteintes des rameaux antérieurs.

A low dose of three local anesthetic solutions for interscalene blockade tested by thermal quantitative sensory testing: a randomized controlled trial.

This randomized double-blind controlled trial compared the block characteristics of three low-dose local anesthetics at different roots in an ultrasound-guided interscalene block, using thermal quantitative sensory testing for assessing the functioning of cutaneous small nerve fibres. A total of 37 adults scheduled to undergo shoulder arthroscopy were randomized to receive 5 mL of either 0.5% levobupivacaine with and without epinephrine 1/200,000 or 0.75% ropivacaine in a single-shot interscalene block. Thermal quantitative sensory testing was performed in the C4, C5, C6 and C7 dermatomes. Detection thresholds for cold/warm sensation and cold/heat pain were measured before and at 30 min, 6, 10 and 24 h after infiltration around C5. The need for rescue medication was recorded. No significant differences between groups were found for any sensation (lowest P = 0.28). At 6 h, the largest differences in sensory thresholds were observed for the C5 dermatome. The increase in thresholds were less in C4 and C6 and minimal in C7 for all sensations. The analgesic effect lasted the longest in C5 (time × location mixed model P < 0.001 for all sensory tests). The time to rescue analgesia was significantly shorter with 0.75% ropivacaine (P = 0.02). The quantitative sensory findings showed no difference in intensity between the local anesthetics tested. A decrease in block intensity, with minimal changes in pain detection thresholds, was observed in the roots adjacent to C5, with the lowest block intensity in C7. A clinically relevant shorter duration was found with 0.75% ropivacaine compared to the other groups. Trial registration NCT 02691442.

Effects of Stellate Ganglion Block on Analgesia Produced by Cervical Paravertebral Block as Established by Quantitative Sensory Testing: A Randomized Controlled Trial.

Objective: To use quantitative sensory testing (QST) to assess whether a stellate ganglion block (SGB) modulates the analgesia induced by cervical paravertebral block (CPVB). Design: A prospective double-blind randomized controlled trial. Setting: Department of Anesthesia, Antwerp University Hospital, October 2011 to December 2015. Subjects: Twenty-eight adults scheduled for arthroscopy of a nonfractured shoulder were enrolled. Methods: Participants were randomly assigned to receive either single CPVB (5 mL of levobupivacaine 0.5%) or combined CPVB + SGB (5 mL and 3 mL of levobubivacaine 0.5%, respectively). The detection thresholds for cold/warm sensations and cold/heat pain were established using thermal QST on the C4-C7 dermatomes before local anesthetic infiltration and at 0.5, 6, 10, and 24 hours thereafter. Our primary outcome was the time course of QST thresholds for the different neurosensitive/nociceptive modalities. As secondary and tertiary outcomes, we evaluated the degree of motor block and the time to first administration of rescue analgesics. Results: We randomized 20 patients. There were no significant differences in the detection thresholds for the neurosensitive/nociceptive modalities, motor block, or timing for rescue analgesics between the groups (P = 0.15-0.94). All patients with CPVB + SGB exhibited Horner's signs, whereas patients in the CPVB group did not exhibit these signs; however, this does not exclude sympathetic block. Conclusions: We were unable to demonstrate any analgesic benefit of CPVB + SGB in arthroscopic shoulder surgery. It is therefore not unreasonable to suppose that pain from soft tissue injuries without bony lesions is transmitted mainly by somatic nerves with no or only minimal involvement of the sympathetic nervous system.

Thermal quantitative sensory testing to assess the sensory effects of three local anesthetic solutions in a randomized trial of interscalene blockade for shoulder surgery.

PURPOSE: This study investigated whether quantitative sensory testing (QST) with thermal stimulations can quantitatively measure the characteristics of an ultrasound-guided interscalene brachial plexus block (US-ISB). METHODS: This was a prospective randomized trial in patients scheduled for arthroscopic shoulder surgery under general anesthesia and US-ISB. Participants and observers were blinded for the study. We assigned the study participants to one of three groups: 0.5% levobupivacaine 15 mL, 0.5% levobupivacaine 15 mL with 1:200,000 epinephrine, and 0.75% ropivacaine 15 mL. We performed thermal QST within dermatomes C4, C5, C6, and C7 before infiltration and 30 min, six hours, ten hours, and 24 hr after performing the US-ISB. In addition, we used QST, a semi-objective quantitative testing method, to measure the onset, intensity, duration, extent, and functional recovery of the sensory block. We also measured detection thresholds for cold/warm sensations and cold/heat pain. RESULTS: Detection thresholds for all thermal sensations within the ipsilateral C4, C5, C6, and C7 dermatomes increased rapidly (indicating the development of a hypoesthetic state) and reached a steady state after 30 min. This lasted for approximately ten hours and returned to normal detection thresholds by 24 hr. There were no differences detected between the three groups at 24 hr when we compared warm sensation thresholds on one dermatome. Visual inspection of the pooled results per dermatome suggests the ability of QST to detect clinically relevant differences in block intensity per dermatome. CONCLUSIONS: Quantitative sensory testing can be useful as a method for detecting the presence and characteristics of regional anesthesia-induced sensory block and may be used for the evaluation of clinical protocols. The three local anesthetic solutions exhibited a similar anesthetic effect. The results support the use of QST to assess block characteristics quantitatively under clinical research conditions. This trial was registered at Clinicaltrals.gov, NCT02271867.

Low-Volume Local Anesthetics for C5 and Supraclavicular Nerve Blocks for Mid and Lateral Clavicle Surgery: A Case Series.

After institutional ethics committee approval and informed consent, 20 patients with clavicle fractures were recruited. An ultrasound-guided C5 root block was performed by injecting 3 mL of 0.5% bupivacaine with a subsequent ultrasound-guided supraclavicular nerve (SCN) block with 3 mL of 0.5% bupivacaine. A combination of low-volume C5 root block and SCN block provided reliable awake anesthesia and postoperative analgesia in patients with fractured clavicles. This technique can avoid a general anesthesia for fractures of the mid and lateral clavicle. Further studies should focus on the optimal volume of local anesthetics required for the success of this technique.

Acute Management, Diagnosis, and Follow-Up of Suspected Perioperative Hypersensitivity Reactions in Flanders 2001-2018.

BACKGROUND: Despite numerous efforts to describe the clinical manifestations and the epidemiology of perioperative hypersensitivity (POH), there remains room to increase awareness among anesthetists and immunologists/allergists. OBJECTIVE: To report the findings of a 17-year survey of suspected POH in Antwerp, Belgium. METHODS: We analyzed clinical and diagnostic data from 715 patients referred because of a suspected POH reaction, between January 1, 2001, and May 31, 2018. A total of 456 patients demonstrating a POH could be queried about subsequent anesthesia. RESULTS: A total of 608 cases formed the final dataset; 208 had a non-life-threatening reaction and 400 a life-threatening reaction. In life-threatening reactions, hypotension was predominating. In the non-life-threatening reactions, 83.9% of the patients displayed cutaneous manifestations. In life-threatening reactions, intravenous adrenaline and fluids were administered in 75.7% and 31%, respectively, and 41.3% had their intervention abandoned. Mast cell activation (MCA) was mainly, but not exclusively, observed in severe grades but did not predict the mechanistic process nor the culprit. A cause was identified in 77.8% of severe and 48.6% of milder cases. Main culprits were neuromuscular blocking agents, latex, cefazolin, and dyes. A total of 156 cases had uneventful anesthesia, except 1 patient who was inadvertently re-exposed to hidden chlorhexidine. CONCLUSIONS: This study highlights that there is room for an improved acute management and an optimized diagnostic workup that should not be restricted to patients with severe reactions and/or showing MCA.