Spread Of Injectate Research Articles

A Novel Ultrasound-Guided Cervical Plexus Block: A Cadaveric Canine Study.

The ultrasound-guided cervical plexus plane (US-CPP) block has proven effective in humans; yet its application in dogs remains unexplored. This study aimed to describe a novel US-CPP approach in canines. A local sonoanatomy was mapped, the injection technique was tested, and a gross anatomical dissection (GAD) was performed on one cadaver. The bilateral injectate spread and nerve staining were then evaluated via a CT scan and GAD in the six cadavers. The transducer was aligned parallel to the cervical spine, caudal to the atlas. After identifying the cleidocervical and omotransversarius muscles and the C2-C3 interfascial plane, a spinal needle was inserted in-plane, and 0.15 mL/kg of a dye-contrast solution was injected. CT imaging showed the contrast reaching the C1, C2, and C3 vertebral bodies in 3 out of 12 (3/12), 11/12, and 12/12 injections, respectively, and the C4, C5, and C6 vertebrae in 8/12, 5/12, and 1/12 injections, respectively. No contrast was detected in the epidural space. The C1, C2, C3, C4, and C5 nerves were stained in 3/12, 10/12, 8/12, 2/12, and 0/12 injections, respectively. No significant differences were observed between the groups (p > 0.05). A single US-CPP injection successfully stained the C2 and C3 nerves, indicating the potential clinical applicability, although the injected volume rarely reached C4 and C5.

Anatomical assessments of injectate spread stratified by the volume of the intertransverse process block at the T2 level

BackgroundThis cadaveric study aimed to analyze injectate spread to target nerves during a single-injection, ultrasound-guided intertransverse process block.MethodsAn ultrasound-guided intertransverse process block with three different injectate volumes was administered to...

Ultrasound-guided sciatic nerve block injections in barred owl (Strix varia) cadavers

ObjectiveTo describe an ultrasound-guided approach to the sciatic nerve and the distribution of nerve staining using two injectate volumes of dye in barred owls. Study designDescriptive, randomized, assessor-blinded, cadaveric study. AnimalsTwelve barred owl cadavers. MethodsThe sciatic nerve was visualized with a 13-6 MHz linear ultrasound probe placed on the medial aspect of the proximal femur in barred owl cadavers. A needle was inserted at the proximal caudal thigh, and cranially advanced in-plane until the tip was immediately adjacent and ventral to the sciatic nerve. Eleven owls were injected bilaterally with a 1:1 solution of 1% methylene blue and 0.5% ropivacaine, with high-volume (HV; 0.4 mL kg–1) and low-volume (LV; 0.2 mL kg–1) treatments. Nerve staining ≥ 1 cm circumferentially was determined by dissection 15 minutes post-injection. The coelom was then opened to inspect for aberrant dye spread. In one barred owl cadaver, a 1:1 solution of 1% methylene blue and 74% ioversol contrast was injected, and computed tomography was performed immediately before and 15 minutes after injection for evaluation of injectate spread. ResultsThe HV treatment (0.4 mL kg–1) resulted in successful nerve staining in 100% of injections, whereas the LV treatment (0.2 mL kg–1) resulted in successful nerve staining in 91% of injections. There was no leakage of injectate into undesired locations (e.g. coelomic cavity) in any cadaver. Conclusions and clinical relevanceIn barred owls, the sciatic nerve can be visualized with ultrasound and injecting a ropivacaine/dye solution under ultrasound guidance successfully stained the sciatic nerve in the majority of cases. This technique holds potential for providing analgesia distal to the stifle joint; however, further investigations are necessary to evaluate its practical application in a clinical setting.

Ganglionic Local Opioid Analgesia at the Superior Cervical Ganglion: MRI-Verified Solution Spread.

Ganglionic local opioid analgesia (GLOA) at the superior cervical ganglion (SCG) is performed for pain control and is known to be an effective procedure. In this study, we evaluated the spread of the injectate in the area of the SCG. Our expectation was that there would be a correlation between the area and volume of the injectate spread and post-procedural outcome measures. This was a retrospective blinded review of magnetic resonance imaging (MRI) scans. Assessors evaluated the anatomical area of fluid spread, the furthermost spread from midline, any hampered spread and contact of contrast fluid with other structures. The efficacy of GLOA and complications were estimated. The main solution spread reached from the C1 to C3 vertebrae. The furthest spread in the lateral and sagittal planes was 21.2 and 15.2mm, respectively. The furthest craniocaudal spread was 63.5mm. In 53.3% and 33% of interventions, the solution was found in the parapharyngeal space and in its "medial compartment," respectively. A correlation was found between pain relief and both solution spread and volume of solution spread. No hampered spread was recorded. A negative correlation between pain reduction and number of GLOA was observed. Higher pre-procedural pain intensity was correlated with higher pain reduction. We estimated pain relief in 93% of procedures correctly. No correlation between post-procedural Numerical Rating Scale (NRS) scores and different needle approaches was found. For the transoral blocking technique, a strict laterodorsal needle direction is recommended to prevent possible block failures. A total volume of 2ml injected into the parapharyngeal space and its "medial compartment" is recommended. Higher volumes may lead to uncontrolled distribution patterns. Clinicaltrials.gov identifier NCT05257655; date of registration 2022-02-25; patient enrollment date from 2023-01-09 to 2023-08-31.

Ultrasound-guided external oblique intercostal block technique in rabbits (Oryctolagus cuniculus): a cadaveric study

BackgroundLocoregional anesthesia is an essential component of multimodal analgesic and anesthetic techniques. However, few are described in rabbits, especially those aimed at the cranial abdominal wall. The aim of this study was to describe the external oblique intercostal (EOI) block technique in rabbits and compare the spread of two injectate volumes across the paracostal region and cranial abdominal wall. MethodsEight rabbit cadavers (16 hemithoraces) were randomized to receive ultrasound-guided injections between the external abdominal oblique and external intercostal muscles. Each rabbit received 0.25 ml/kg (LV) and 0.5 ml/kg (HV) of 1% new methylene blue with immediate tissue dissection. Site of needle insertion, spread of injectate, and number of stained intercostal spaces and nerves were assessed by a blinded investigator. ResultsInjection points ranged from intercostal spaces 5-12. There were no differences between HV and LV groups in the number of covered intercostal spaces or dorsal, caudal, and total (cranial + caudal) spread. There was significantly more ventral and cranial spread in the HV group as well as staining of intercostal nerves. Conclusions and Clinical RelevanceInjection within the EOI fascial plane successfully stained intercostal nerves associated with the thoracic wall and cranial abdomen; higher volumes provided significantly more spread in the cranial and ventral directions and stained more intercostal nerves. While the EOI block using a volume of 0.5 ml/kg could be a technique used to provide regional anesthesia of the rabbit paracostal region and cranial abdomen, future studies would be needed to determine clinical safety and efficacy.

Transversus Abdominis Plane (TAP) Block in Rabbit Cadavers: Anatomical Description and Measurements of Injectate Spread Using One- and Two-Point Approaches.

The aim of this study was to describe one-point (preiliac approach) and two-point (preiliac and retrocostal approach) blocks of the Transversus Abdominis Plane (TAP) on a cadaveric model. For this purpose, ultrasound-guided infiltration of the plane between the internal oblique and transversus abdominis muscles was performed and, after dissection of tissues, the areas and percentage of nerve fibers involved were analyzed. Injection into the TAP plexus of a 1 mL/kg solution of 2% lidocaine and 1% methylene blue (1:1) was performed in 30 rabbit cadavers. In fifteen rabbits (group S), the solution was inoculated at the preiliac level. In the other 15 rabbits (group D), the solution was divided into two inoculations (0.5 mL/kg at the retrocostal level and 0.5 mL/kg at the preiliac level). All cadavers were then dissected and stained spinal nerve branches were measured. Moreover, the percentage of length, height and the total area of the stained tissue were calculated. In the S group, T10, T11 and T12 nerve eminences were successfully stained in 18%, 52% and 75% of cases, respectively. Furthermore, L1, L2, L3 and L4 were stained in 95%, 100%, 60% and 40% of cases, respectively. In group D, the ventromedial eminence of T10, T11 and T12 were stained in 68.1%, 100% and 98% of cases, respectively, and L1, L2, L3 and L4 were stained in 88%, 100%, 62% and 31% of cases, respectively. In conclusion, a two-point TAP block is more effective in covering the nerve eminences of the cranial abdomen than the preiliac approach alone.

Craniocaudal spread and clinical translation for combined erector spinae plane block and retrolaminar block in soft embalmed cadavers: a randomised controlled equivalence study

BackgroundErector spinae plane (ESP) block spread can be unpredictable. We previously improved the spread of ESP injection by addition of retrolaminar (RL) injection. However, it is not clear whether spread at high thoracic levels is similar to spread at midthoracic levels. Our primary objective was to demonstrate that craniocaudal dye spread was equivalent after combined ESP and RL injection using a 19 G Tuohy needle at the third (T3) and sixth (T6) vertebrae in soft embalmed Thiel cadavers. MethodsWe randomised 20 combined ESP and RL injections to the T3 and T6 vertebral levels on both sides of 10 prone Thiel cadavers. A 3–8 MHz transducer was placed in the paramedian sagittal plane and a single anaesthetist injected 10 ml dye onto the transverse process, then 10 ml dye onto the laminae of T3 or T6. Cadavers were dissected 24 h later. ResultsMean (sd) craniocaudal spread of dye after combined ESP + RL injection at T3 and T6 vertebral levels was equivalent: 8.6 (1.8) vs 8.7 (2.3) levels, respectively; difference (90% confidence interval): –0.1 (–1.4 to 1.6), P=0.904. Dye extended uniformly, cranially and caudally, from the point of injection. A 3D prosection created from a Thiel cadaver confirmed that the dorsal ramus emerges from the costotransverse foramen deep to the intertransverse ligament within the retro-superior costotransverse ligament space. Combined ESP and RL block in six patients before mastectomy achieved extensive anterior, lateral, and posterior chest wall paraesthesia over four to six dermatomes. ConclusionsCombined ESP and RL injections showed equivalent and consistent spread at T3 and T6 injection sites. A pilot study confirmed translation to patients.

The spread of injectate after deep serratus anterior plane and superficial parasternal intercostal plane blocks: a cadaveric dye study.

We investigated the distribution of injected dye after deep serratus anterior plane and superficial parasternal intercostal plane blocks in 15 Thiel embalmed cadavers. We injected 0.4 ml.kg-1 of 0.25% aqueous methylene blue solution into the deep serratus anterior and superficial parasternal intercostal planes using real-time ultrasound needle visualisation followed by posterior dissection to observe the distribution of the injected dye in the chest wall. The two blocks were performed bilaterally in 15 cadavers at the T5/T6 level, comprising 60 blocks in 30 hemithoraces in total. At dissection, the intercostal nerve territories were observed to be dyed completely from T2 to T6 in 28 of 30 hemithoraces, and extending caudal to T6 in 10 hemithoraces. Following the deep serratus anterior plane blocks in all cadavers, the dye was found to have spread to the axillae. Following the superficial parasternal intercostal plane blocks, the dye reached T7 in four cadaver dissections. We concluded that the territories innervated by the intercostal nerves (T2-T6 dermatomes) are dyed following the combination of the two blocks when performed at the T5-T6 intercostal space level. These techniques might provide an effective option for anaesthesia in breast surgery.

Ultrasound-guided caudal quadratus lumborum block combined with the greater ischiatic notch plane block as motor-protective analgesia for the pelvic limb in dogs

ObjectiveTo develop an ultrasound-guided caudal quadratus lumborum block (C-QLB) technique in canine cadavers and to compare sensory and motor blockade resulting from the combination of ultrasound-guided greater ischiatic notch (GIN) plane and C-QLB approaches (GIN-CQLB group) versus a lumbosacral plexus (LSP group) approach [combination of lateral pre-iliac (LPI) and parasacral (PS) techniques] in dogs. Study designDescriptive anatomical study and prospective randomized, blinded, experimental crossover trial. AnimalsA total of six canine cadavers and six adult Beagle dogs. MethodsPhase I: following ultrasound-guided C-QLB injections of 0.3 mL kg–1 of dye, using the interfascial plane located lateral to the quadratus lumborum muscle at the level of the sixth lumbar vertebra (L6) as injection point, the spread of injectate and nerve staining was evaluated using gross anatomical dissection. Phase II: sensory and motor blockade achieved with the GIN-CQLB or LSP blocks in Beagle dogs were evaluated and compared. The assigned technique was performed with 2% lidocaine: 0.2 mL kg–1 for the GIN and PS approaches and 0.3 mL kg–1 for the C-QLB and LPI approaches. ResultsDissection revealed distribution of dye around the lumbar hypaxial musculature, extending into the paravertebral spaces, with staining of 3 (2–4) [median (interquartile range)] spinal nerves, spanning L3 to L6. The median motor blockade in the GIN-CQLB and LSP groups was 7 (7–8) versus 16 (10–16) (p = 0.026), whereas the median sensory blockade was 5 (4–5) versus 3 (3–3) (p = 0.025), respectively. Conclusion and clinical significanceThe GIN-CQLB approach desensitized the thigh dermatomes effectively. Compared with the LSP approaches, GIN-CQLB exhibits a motor-protective effect by preserving tonic muscle function.

Injectate spread following ultrasound-guided caudal quadratus lumborum block in dogs: a cadaveric study

Injectate spread following ultrasound-guided caudal quadratus lumborum block in dogs: a cadaveric study

Thoracolumbar Retrolaminar Block: Anatomical and Radiological Study of Injectate Pattern Distribution in Canine Cadavers.

The retrolaminar block is a regional anaesthetic technique, first developed in humans, in which the local anaesthetic is deposited directly onto the dorsal aspect of the thoracic or lumbar vertebral lamina. This study aims to evaluate the distribution of landmark-guided thoracolumbar retrolaminar injections in greyhound cadavers. Thirteen injections of contrast-dye solution were performed in eight cadavers at the level of the twelfth thoracic vertebra (T12), with either 20 mL (n = 8, high volume, HV) or 10 mL (n = 5, low volume, LV) per site. The spread of the injectate was evaluated through computed tomography and transverse anatomical dissection. The groups were compared using the Mann-Whitney U test. The median (range) of the extent of the spread was 4 (2-5) and 3 (2-4) intervertebral foramina in the LV and HV groups, respectively. The median (range) of the spread along the retrolaminar space was 3 (2-3) retrolaminar segments in the LV and 3 (2-4) in the HV group. Epidural and retroperitoneal spread was identified in seven cadavers. Following landmark-guided retrolaminar injections, the injectate spread both in the retrolaminar and paravertebral spaces, without any obvious association between the volume of injectate and the extent of the spread. Further studies are warranted to determine the clinical efficacy of the technique.

Superficial versus deep parasternal intercostal plane blocks: cadaveric evaluation of injectate spread

BackgroundDeep and superficial parasternal intercostal plane blocks provide anterior chest wall analgesia for both breast and cardiac surgery. Our primary objective of this cadaveric study was to describe the parasternal spread of deep and superficial parasternal intercostal plane blocks. Our secondary objectives were to describe needle proximity to the internal mammary artery when performing deep parasternal intercostal plane blocks, and compare lateral injectate spread and extension into the rectus sheath. MethodsWe performed ultrasound-guided deep and superficial parasternal intercostal plane blocks 2 cm from the sternum at the T3–4 interspace in four fresh frozen cadavers as described in clinical studies. ResultsParasternal spread of injectate was greater with the deep parasternal intercostal plane injection than with the superficial parasternal intercostal plane injection. The internal mammary artery was ∼3 mm away from the needle trajectory in cadaver #1 and ∼5 mm from the internal mammary artery in cadaver #2. Lateral spread extended to the midclavicular line for all deep parasternal intercostal plane blocks and beyond the midclavicular line for all superficial parasternal intercostal plane blocks. Neither block extended to the rectus sheath. ConclusionsA greater number of parasternal interspaces were covered with the deep parasternal intercostal plane block than with the superficial parasternal intercostal plane block when one injection was performed at the T3–4 interspace. However, considering proximity to the internal mammary artery, and potential devastating consequences of an arterial injury, we propose that the deep parasternal intercostal plane block be classified as an advanced block and that future studies focus on optimising superficial parasternal intercostal plane parasternal spread.

Comparison of injectate spread and nerve coverage between single-injection intertransverse process block and paravertebral block at the T2 level: a cadaveric study

BackgroundWe compared the spread of an injectate into the thoracic sympathetic chain resulting from a single-injection intertransverse process (ITP) block with that of a single-injection PV block at the T2...

Superficial versus deep parasternal intercostal plane blocks: a cadaveric evaluation of injectate spread

Superficial versus deep parasternal intercostal plane blocks: a cadaveric evaluation of injectate spread

A radiological cadaveric study of obturator nerve involvement and cranial injectate spread after different approaches to the fascia iliaca compartment block

Whether the fascia iliaca compartment block (FICB) involves the obturator nerve (ON) remains controversial. Involvement may require that the injectate spreads deep in the cranial direction, and might thus depend on the site of injection. Therefore, the effect of suprainguinal needle insertion with five centimeters of hydrodissection-mediated needle advancement (S-FICB-H) on ON involvement and cranial injectate spread was studied in this radiological cadaveric study. Results were compared with suprainguinal FICB without additional hydrodissection-mediated needle advancement (S-FICB), infrainguinal FICB (I-FICB), and femoral nerve block (FNB). Seventeen human cadavers were randomized to receive ultrasound-guided nerve block with a 40 mL solution of local anesthetic and contrast medium, on both sides. Injectate spread was objectified using computed tomography. The femoral and lateral femoral cutaneous nerves were consistently covered when S-FICB-H, S-FICB or FNB was applied, while the ON was involved in only one of the 34 nerve blocks. I-FICB failed to provide the same consistency of nerve involvement as S-FICB-H, S-FICB or FNB. Injectate reached most cranial in specimens treated with S-FICB-H. Our results demonstrate that even the technique with the most extensive cranial spread (S-FICB-H) does not lead to ON involvement and as such, the ON seems unrelated to FICB. Separate ON block should be considered when clinically indicated.

Adductor canal block techniques do not lead to involvement of sciatic nerve branches: a radiological cadaveric study

IntroductionLow and high volume mid-thigh (ie, distal femoral triangle) and distal adductor canal block approaches are frequently applied for knee surgical procedures. Although these techniques aim to contain the injectate...

Investigation of the existence of and a block technique for the inferior lateral genicular nerve: cadaveric study.

Among the four genicular nerves innervating the anterior aspect of the knee, the inferior lateral genicular nerve has been omitted as a target of blocking. Some authors have suggested that the inferior lateral genicular nerve of the knee might pass beneath the lateral collateral ligament of knee. The authors aimed to study the location of the inferior lateral genicular nerve and the spread of injectate during the inferior lateral genicular nerve block. In ten knees from fresh frozen cadavers, the authors performed on each an ultrasound-guided block of the inferior lateral genicular nerve of the knee just below the lateral collateral ligament. The needle was inserted below the lateral collateral ligament, and 2 mL of blue dye was injected. A week later, the cadavers were dissected, and the existence of the inferior lateral genicular nerve and the spread of dye around it was investigated. The proportion of inferior lateral genicular nerves branching from the common peroneal nerve was found in 8 of 10 (80.0%) cadavers. Of these eight cadavers with inferior lateral genicular nerve, five specimens (62.5%) were stained with blue dye. The common peroneal nerve was not infiltrated with dye in any specimens. When 2 mL of dye was inserted inferiorly to the lateral collateral ligament, the inferior lateral genicular nerve could be blocked in 62.5% of specimens. Because the common peroneal nerve was not involved in any specimen, motor weakness would be avoided with this method.

Development of an in situ emulsifying/ultra-low-interfacial-tension cyclic flooding system for medium- and low-permeability reservoirs

Medium- and low-permeability reservoirs are important in oilfield development. However, due to their characteristics of poor pore permeability and high heterogeneity, the development of suitable technologies has been very difficult. In this study, an in situ emulsifying/ultra-low-interfacial-tension cyclic flooding system has been developed for low- and medium-permeability reservoirs. Based on the hydrophilic-lipophilic balance (HLB) value method, an emulsifying surfactant ASD with Span 80 (sorbitan monooleate) as the main component has been identified as highly promising through screening. At mass fractions of surfactant ASD between 0.2% and 0.6%, the extent of water separation from the emulsion is greatly reduced, and the W/O emulsion can effectively improve the mobility ratio and increase the sweep volume. The surfactant SA synthesized in our laboratory reduces the interfacial tension of crude oil to 10−4 mN m−1. Laboratory core flooding experiments have shown that multiple rounds of alternating injection with aqueous solutions of surfactants ASD and SA can improve oil recovery by 22.25%. Upon injecting a low-viscosity aqueous solution of surfactant ASD, it emulsifies crude oil in situ under reservoir conditions, solving the problems of difficult polymer injection and insufficient spread. Our work provides useful insights for the development of low- and medium-permeability reservoirs.

Ultrasound-Guided Lumbar Peri-Facet Joint Blocks: A Therapuetuic Approach to Chronic Lower Back and Referred Leg Pain Management

Intra-articular fluoroscopically-guided facet joint (FJ) blocks are performed with diagnostic-therapeutic aims, whereas the main focus of ultrasound guided peri-facet joint blocks (USG-PFJB) is pain relief. USG-PFJB will therefore typically utilize higher injection volumes to potentially offer injection spread to other pain-generating structures. This study explores the potential role of USG-PFJBs in the outpatient management of chronic low back pain with our without leg symptoms in patients with MRI-confirmed mild to severe lower lumbar FJ arthrosis. USG-PFJBs were performed on 19 patients, (4 male and 15 females, mean age 55) at the L4/5 and/or L5/S1 segments at paraspinal points of palpable focal pain. All procedures were performed by the same clinician. One patient was lost to follow up and telephone reviews at 2-6 months on the remaining 18 patients, noted that 59.73% experienced significant & sustained pain relief. In conclusion, lower lumbar segment USG-PFJBs appear to be effective treatment option in patients with mild to severe MRI-confirmed FJ degeneration and palpable paraspinal lower back pain and with or without lower limb pain.

Evaluating the Extent of Ultrasound-Guided Cervical Selective Nerve Root Block in the Lower Cervical Spine: Evidence Based on Computed Tomography Images.

To verify the injectate dispersal patterns (IDP) and therapeutic outcome of ultrasound-guided cervical selective nerve root block (UG-SCNRB) in treating cervical radiculopathy (CR). Overall, 18 CR patients were recruited to undergo UG-SCNRB in the CT room. Following placement of the puncture needle tip between the target nerve root and posterior tubercle, 3 mL of the drug was administered per root (0.33% lidocaine 0.5 mL + Compound betamethasone injection 0.5mL + methylcobalamin injection 1mL + iohexol 1mL). Subsequently, the IDP was assessed on postintervention CT scan images. In all, 18 participants were analyzed. We injected 21 target cervical nerve roots, namely, 1 C4 nerve, 9 C5 nerves, and 11 C6 nerves. Among the IDPs on postintervention CT scan images, two IDPs were most prevalent, namely, the contrast spread into the extraforaminal spaces (Zone I, the interscalene) in 100% (21/21) of cases, and the foraminal space spread (Zone II) in 61.90% (13/21) of cases. The injectate spread into the epidural spaces (Zone III) in only 2 out of 21 cases (9.52%). The pain relief was significantly improved two hours after surgery, compared to the preoperative VAS pain scores (2 hours, 1.39±0.50 vs VAS at baseline, P<0.01). The VAS pain scores during follow-up were significantly lower than preoperation (1 weeks, 1.94±0.54 vs VAS at baseline; 2 weeks, 2.61±0.70, P<0.01 vs VAS at baseline; 4 weeks, 2.67±0.59, P<0.01 vs VAS at baseline). We verified, via CT imaging, that the UG-SCNRB drug diffusion was within safe range (the injectate mainly spread to the extraforaminal spaces), and without any serious complications, such as, intravascular drug injection, extensive diffusion of the epidural space, and general spinal anesthesia.