No abstract

This anatomical study shows that an ultrasound-guided TAP injection cephalad to the iliac crest is likely to involve the T10-L1 nerve roots, and implies that the technique may be limited to use in lower abdominal surgery.

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.

BackgroundThere is heterogeneity in the names and anatomical descriptions of regional anesthetic techniques. This may have adverse consequences on education, research, and implementation into clinical practice. We aimed to produce standardized nomenclature for abdominal wall, paraspinal, and chest wall regional anesthetic techniques.MethodsWe conducted an international consensus study involving experts using a three-round Delphi method to produce a list of names and corresponding descriptions of anatomical targets. After long-list formulation by a Steering Committee, the first and second rounds involved anonymous electronic voting and commenting, with the third round involving a virtual round table discussion aiming to achieve consensus on items that had yet to achieve it. Novel names were presented where required for anatomical clarity and harmonization. Strong consensus was defined as ≥75% agreement and weak consensus as 50% to 74% agreement.ResultsSixty expert Collaborators participated in this study. After three rounds and clarification, harmonization, and introduction of novel nomenclature, strong consensus was achieved for the names of 16 block names and weak consensus for four names. For anatomical descriptions, strong consensus was achieved for 19 blocks and weak consensus was achieved for one approach. Several areas requiring further research were identified.ConclusionsHarmonization and standardization of nomenclature may improve education, research, and ultimately patient care. We present the first international consensus on nomenclature and anatomical descriptions of blocks of the abdominal wall, chest wall, and paraspinal blocks. We recommend using the consensus results in academic and clinical practice.

Transversus abdominus plane block using 3 mg kg(-1) of ropivacaine produces venous plasma concentrations that are potentially neurotoxic, although broadly consistent with plasma levels found after injection at other comparable sites.

SummaryExisting 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.

Abdominal surgery can cause significant postoperative pain and associated morbidity. Systemic opioids often contribute to side-effects such as sedation, respiratory depression, nausea and vomiting. Postoperative epidural analgesia offers superior analgesia and reduced pulmonary morbidity compared to systemic analgesia 1 , however several reports have alluded to a recent decline in its utilisation following abdominal surgery 2-4. This has occurred on a background of large clinical trials that have failed to demonstrate improved survival following major surgery 1,5 and large studies focusing on morbidity due to epidural analgesia 6-8. Although neurological disability following central neuraxial block is rare, medicolegal concerns can dominate clinical decision-making regarding anaesthesia options. Postoperative epidural analgesia requires ongoing clinical care and surveillance, whereas systemic opioids may have less demand on clinical resources. Furthermore, there is a current trend towards minimally invasive surgical procedures, hence an increasing role for emerging less invasive analgesia techniques. One less invasive analgesic technique is transversus abdominis plane (TAP) block. This technique involves injection of local anaesthetic into the fascial plane between internal oblique and transversus abdominis muscles, where the thoracolumbar nerves T6 to L1 course before innervating the anterior abdominal wall 9. Results from three randomised control trials, utilising anatomical landmark techniques have

SummaryUltrasound-guided transversus abdominis plane (TAP) block can be performed using a subcostal technique. This technique was simulated using dye injection in cadavers in order to determine segmental nerve involvement and spread of injectate using either single or multiple-injection techniques. Dye most commonly spread to affect T9 and T10 nerves with the single injection technique and T9, T10 and T11 with multiple injections. The median (IQR [range]) spread of dye was 60 (36-63 [32-78]) cm 2 using the single-injection technique and 90 (85-96 [72-136]) cm 2 , in the multiple-injection technique, and this difference was statistically significant (p = 0.003). These results indicate that ultrasound-guided subcostal TAP block will involve nerve roots T9, T10 and T11 and that a multiple-injection technique may block more segmental nerves and increase spread of injectate. The transversus abdominis plane (TAP) block is a regional anaesthesia technique where local anaesthetic is injected into the neurovascular plane between the transversus abdominis and internal oblique muscles. The ventral rami of the segmental thoracolumbar nerves course through the TAP before innervating the anterolateral abdominal wall. The TAP block has been shown to provide postoperative analgesia following abdominal surgery [1][2][3]. These studies have utilised a landmark technique where the injection point into the TAP is through the lumbar triangle in the lateral abdominal wall [4,5]. The TAP block can also be performed with ultrasound imaging to guide injection of local anaesthetic into the neurovascular plane [6][7][8][9]. Real-time imaging of the needle trajectory and injectate spread may improve both safety and block effectiveness. The goal of the TAP block is to anaesthetise several segmental nerves, and recently, we described the extent of nerve involvement using a dye injection study in a cadaver model that simulated an ultrasound-guided TAP block. The probe was placed on the anterolateral abdominal wall between the iliac crest and the costal margin and the needle advanced from an anterior and medial location in a posterolateral direction so that the needle entry point into the TAP was relatively posterior. Using that approach, thoracolumbar nerves, T11, T12 and L1 were the nerves most commonly affected with dye [10].An alternative ultrasound-guided technique is the subcostal TAP block where the probe is placed immediately inferior to the costal margin on the anterior abdominal wall, and an injection made at this location [11]. As a clinical technique, the subcostal ultrasoundguided TAP block may have a different pattern and extent of segmental nerve involvement compared to the posterior technique; hence the primary objective of this anatomical study was to determine the pattern and extent of injectate spread, as measured by segmental nerve involvement with dye and area of dye spread following a simulated ultrasound-guided subcostal TAP block in cadavers. Ultrasound-guided TAP block can be performed using a single-injection or a mul...