Functional anatomy of the nerve and optimal placement of the needle for successful (and) safe nerve blocks

Comparison of the Efficacy Between Ultrasound-Guided Paravertebral Block and Erector Spinae Block for Postoperative Analgesia in Percutaneous Nephrolithotomy Using Levobupivacaine: A Prospective and Randomized Study

Introduction Various techniques have been developed in the current era of regional anesthesia practice. With the advent of ultrasound, the visualization of needle and pleura in real time enables a better outcome with negligible adverse events. This study was designed to compare the efficacy between ultrasound-guided erector spinae plane block (ESPB) and paravertebral block (PVB) in percutaneous nephrolithotomy (PCNL) for the duration of postoperative analgesia with levobupivacaine, a local anesthetic with higher lipid solubility, making it more potent and resulting in a longer duration of action. Methods This prospective randomized single-blinded study enrolled 50 patients of ASA grades I and II, aged between 20 and 60 years, who were scheduled for PCNL under general anesthesia. Patients were divided into two groups of 25 each: group ESPB and group PVB, and 25 mL of 0.25% levobupivacaine was administered to both groups. They were primarily evaluated for the duration of postoperative analgesia. Total rescue analgesic requirements, hemodynamic parameters, and any adverse effects were also assessed. Results Both ESPB and PVB provided a significant duration of analgesia postoperatively. Demographic characteristics in both groups were comparable. The duration of postoperative analgesia in group ESPB was 746 ± 58.6 minutes when compared to group PVB, which is 768 ± 68.6 minutes (p = 0.08). Intravenous (IV) paracetamol was used as a rescue analgesic. The doses used were also comparable in both groups, with the visual analog score (VAS) being high after around 12 hours of surgery. The total rescue analgesic requirement was similar in both groups (group ESPB, 2.0 ± 1.6; group PVB, 2.2 ± 1.4; p = 0.51). There were no significant hemodynamic or other adverse effects in either group. Conclusion We conclude that both ESPB and PVB using isobaric levobupivacaine 0.25% as a local anesthetic are equally efficacious in providing effective postoperative analgesia in patients undergoing PCNL under general anesthesia.

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

OBJECTIVE

To 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 DESIGN

Descriptive anatomical study and prospective randomized, blinded, experimental crossover trial.

ANIMALS

A total of six canine cadavers and six adult Beagle dogs.

METHODS

Phase 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.

RESULTS

Dissection 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 SIGNIFICANCE

The 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.

Recent advancements in regional anaesthesia

Patient safety, improved quality of care, and better patient satisfaction and functional outcomes are currently the topmost priorities in regional anaesthesia (RA) and all advancements in RA move in this direction. Ultrasonography-guided central neuraxial and peripheral nerve blocks, intracluster and intratruncal injections, fascial plane blocks, diaphragm-sparing blocks, use of continuous nerve block techniques, and continuous local anaesthetic wound infiltration catheters are now topics of popular clinical interest. The safety and efficacy of nerve blocks can be improved with the help of injection pressure monitoring and the incorporation of advanced technology in the ultrasound machine and needles. Novel procedure-specific and motor-sparing nerve blocks have come up. The anaesthesiologist of the current era, with a good understanding of the sonoanatomy of the target area and the microarchitecture of nerves, along with the backup of advanced technology, can be very successful in performing RA techniques. RA is rapidly evolving and revolutionising the practice of anaesthesia.

Accuracy of ultrasonography predicting spread location following intraneural and subparaneural injections: a scoping review

INTRODUCTION

Ultrasonography is useful for detecting intraneural injections. However, the reliability of the sonographic findings of intraneural and subparaneural injections in terms of true spread location and their association with intrafascicular deposits has not been systematically evaluated.

EVIDENCE ACQUISITION

Our objectives were: i) to explore the reliability of sonographic findings of intraneural and subparaneural injections when validated with tests of true spread such as histology, dissection or imaging, and ii) to evaluate their association with intrafascicular deposits. A Scoping Review was conducted according to Joanna Briggs guidelines. Cinahl, PubMed, ProQuest, ScienceDirect, Scopus and Cochrane databases were searched for studies on adults, cadavers and animal models. Paediatric studies were excluded.

EVIDENCE SYNTHESIS

The search strategy found 598 citations. Following screening, 19 studies were selected. Intraneural injections occurred in the brachial plexus, sciatic, femoral and median nerves. Subparaneural injections in popliteal, supraclavicular and interscalene blocks. Sixteen different ultrasound findings were used to label injection location. Subepineural deposits within individual nerves occurred occasionally following subparaneural injections, regardless of nerve expansion. Overall five studies reported intrafascicular deposits, two of which frequently, following intraneural and subparaneural injections. None of the currently used ultrasound findings was predictive of intrafascicular deposits.

CONCLUSIONS

Our results suggest that sonographic parameters of intraneural and subparaneural injections are reliable in terms of detecting spread location. Intrafascicular injectate deposition may occur, albeit infrequently, particularly in the proximal brachial plexus. Our findings support the judicious interrogation of sonographic parameters suggestive of incipient intraneural injection.

The practice of regional anesthesia in Belgium – a national survey

Background : National surveys are useful to assess the state of regional anaesthesia (RA) practice in a particular country. Given that such information was lacking in Belgium, we conducted a survey to evaluate the Belgian practice of peripheral nerve blocks (PNBs) with a particular focus on its safety aspects. Methods : A survey was sent by email to 1510 Belgian anesthesiologists. No identifying information was collected. Data were collected between September 2019 and October 2019. Results : We collected 324 questionnaires (response rate 21%). Eighty five percent of respondents perform regularly PNB. 99% place a venous access before performing a block, and more than 90% monitor patients with minimum peripheral pulse oximetry. The majority monitor patients for a minimum of 30 minutes after the injection of local anesthetic (LA). Ultrasound-guided technique for RA is used by 89% of respondents. Neurostimulation is totally abandoned by 20% of them. Monitoring of injection pressures is performed by 21% of respondents. More than 50% of respondents use sterile gloves, surgical drapes and a mask. With regards to the solution of LA used, 52% of respondents never mix LAs. An adjuvant is always used by 15% of the respondents while 10% of them never use them. Conclusions : This survey suggests that the practice of PNBs in Belgium is in line with the current international guidelines. This survey can serve as a benchmark for future evaluation and comparison between RA techniques. These observations should be taken into account for the implementation of national guidelines and therefore for the improvement of safety in the practice of PNBs.

Does subepineural injection damage the nerve integrity? A technical report from four amputated limbs

Local anesthetic (LA) injection outside the sheath in epineural or paraneural connective tissue is considered safe practice among regional anesthesiologists. There is limited evidence as to whether neurological complications occur if LA is injected inside the sheath (subepineural - intraneural). We performed ultrasound guided injections at the level of undivided sciatic nerve in four amputated lower limbs. In two specimens, LA was injected in epineural connective tissue (paraneural tissue) and in another two specimens by penetrating the outer nerve sheath (hyperechoic epineurium). Ultrasonography demonstrated an increase in the size of nerve and macroscopic findings revealed fascicular tracings with sub-epineural injections. Limbs were sent for histological analysis in formalin containers. Pathologist performed the analysis which demonstrated an intact perineurium and a breach in the epineurium. We conclude that sub-epineural injections are unsafe and injection should be done in paraneural tissue to ensure safety and avoid unwanted neurological sequelae after the block.

Short-Term Effects of Deliberate Subparaneural or Subepineural Injections With Saline Solution or Bupivacaine 0.75% in the Sciatic Nerve of Rabbits

Background: Ultrasound (US)-guided techniques for peripheral nerve blockade have revealed that intraneural injections are relatively frequent and not necessarily associated with neurological deficits. Objectives: To evaluate the short-term effects of deliberate injections performed under direct vision in two different sites of the sciatic nerve (ScN). Material and Methods: Seventy-two New Zealand white rabbits randomly assigned to one of four experimental groups (n = 18) were employed. All procedures were conducted at a proximal femoral level where the ScN incorporates the common peroneal nerve and the tibial nerve (TN). Fixed volumes of 0.5 ml of saline solution (ES group) or bupivacaine 0.75% (EB group) were administered extrafascicularly inside the paraneurium of the ScN or intrafascicularly (IS and IB groups) under the epineurium of the TN. Cross-sectional area (CSA) and relative echogenicity (RE) of the entire ScN were determined by US before injections, after injections, and at 3 and 7 days. ScN samples were obtained for structural and ultrastructural histopathological studies. Proprioceptive, sensorial, and motor function were clinically evaluated on a daily basis. Results: The CSA of the ScN increased significantly immediately after injections when compared with pre-injection values in all groups (p < 0.05). The RE of the ScN decreased in relation to pre-injection values in all groups (p < 0.05). The CSA and RE of the ScN returned to normal values 7 days after injections in almost all groups. Injected nerves showed histological signs of mild perineural inflammation. Histopathological scores were not significantly different between groups (p > 0.05). The architecture of the ScN was preserved in all rabbits at 3 days and in 31/32 rabbits at 7 days. A focal area of damaged nerve fibers with degeneration of the axons and myelin sheath affecting the TN was observed in one rabbit of the IB group. Nerve function was not clinically impaired in any case. Conclusion: Despite the lack of severe nerve disruption observed in most rabbits, the evidence of a focal area of damaged nerve fibers in one rabbit injected intrafascicularly with bupivacaine confirms that intrafascicular injections should be avoided as they may increase the risk of nerve damage.