Michael J. Barrington

Preliminary Results of the Australasian Regional Anaesthesia Collaboration: A Prospective Audit of More Than 7000 Peripheral Nerve and Plexus Blocks for Neurologic and Other Complications

Background and Objectives: Peripheral nerve blockade is associated with excellent patient outcomes after surgery; however, neurologic and other complications can be devastating for the patient. This article reports the development and preliminary results of a multicenter audit describing the quality and safety of peripheral nerve blockade. Methods: From January 2006 to May 2008, patients who received peripheral nerve blockade had data relating to efficacy and complications entered into databases. All patients who received nerve blocks performed by all anesthetists during each hospitals contributing period were included. Patients were followed up by phone to detect potential neurologic complications. The timing of follow-up was either at 7 to 10 days or 6 weeks postoperatively, depending on practice location and time period. Late neurologic deficits were defined as a new onset of sensory and/or motor deficit consistent with a nerve/plexus distribution without other identifiable cause, and one of the following: electrophysiologic evidence of nerve damage, new neurologic signs, new onset of neuropathic pain in a nerve distribution area, paresthesia in relevant nerve/plexus distribution area. Results: A total of 6950 patients received 8189 peripheral nerve or plexus blocks. Of the 6950 patients, 6069 patients were successfully followed up. In these 6069 patients, there were a total of 7156 blocks forming the denominator for late neurologic complications. Thirty patients (0.5%) had clinical features requiring referral for neurologic assessment. Three of the 30 patients had a block-related nerve injury, giving an incidence of 0.4 per 1000 blocks (95% confidence interval, 0.08-1.1:1000). The incidence of systemic local anesthetic toxicity was 0.98 per 1000 blocks (95% confidence interval, 0.42-1.9:1000). Conclusions: These results indicate that the incidence of serious complications after peripheral nerve blockade is uncommon and that the origin of neurologic symptoms/signs in the postoperative period is most likely to be unrelated to nerve blockade.

Determination of spread of injectate after ultrasound-guided transversus abdominis plane block: a cadaveric study

BACKGROUND The transversus abdominis plane (TAP) block is a new regional anaesthesia technique that provides analgesia after abdominal surgery. It involves injection of local anaesthetic into the plane between the transversus abdominis and the internal oblique muscles. The TAP block can be performed using a landmark technique through the lumbar triangle or with ultrasound guidance. The goal of this anatomical study with dye injection into the TAP and subsequent cadaver dissections was to establish the likely spread of local anaesthesia in vivo and the segmental nerve involvement resulting from ultrasound-guided TAP block. METHODS An ultrasound-guided injection of aniline dye into the TAP was performed for each hemi-abdominal wall of 10 unembalmed human cadavers and this was followed by dissection to determine the extent of dye spread and nerve involvement in the dye injection. RESULTS After excluding one pilot specimen and one with advanced tissue decomposition, 16 hemi-abdominal walls were successfully injected and dissected. The lower thoracic nerves (T10-T12) and first lumbar nerve (L1) were found emerging from posterior to anterior between the costal margin and the iliac crest. Segmental nerves T10, T11, T12, and L1 were involved in the dye in 50%, 100%, 100%, and 93% of cases, respectively. CONCLUSIONS 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.

Refining the course of the thoracolumbar nerves: a new understanding of the innervation of the anterior abdominal wall.

Previous descriptions of the thoracolumbar spinal nerves innervating the anterior abdominal wall have been inconsistent. With modern surgical and anesthetic techniques that involve or may damage these nerves, an improved understanding of the precise course and variability of this anatomy has become increasingly important. The course of the nerves of the anterior abdominal is described based on a thorough cadaveric study and review of the literature. Twenty human cadaveric hemi‐abdominal walls were dissected to map the course of the nerves of the anterior abdominal wall. Dissection included a comprehensive tracing of nerves and their branches from their origins in five specimens. The branching pattern and course of all nerves identified were described. All thoracolumbar nerves that innervate the anterior abdominal wall were found to travel as multiple mixed segmental nerves, which branch and communicate widely within the transversus abdominis plane (TAP). This communication may occur at multiple locations, including large branch communications anterolaterally (intercostal plexus), and in plexuses that run with the deep circumflex iliac artery (DCIA) (TAP plexus) and the deep inferior epigastric artery (DIEA) (rectus sheath plexus). Rectus abdominis muscle is innervated by segments T6‐L1, with a constant branch from L1. The umbilicus is always innervated by a branch of T10. As such, identification or damage to individual nerves in the TAP or within rectus sheath is unlikely to involve single segmental nerves. An understanding of this anatomy may contribute to explaining clinical outcomes and preventing complications, following TAP blocks for anesthesia and DIEA perforator flaps for breast reconstruction. Clin. Anat. 21:325–333, 2008.

Ultrasound guidance reduces the risk of local anesthetic systemic toxicity following peripheral nerve blockade.

Background and Objectives Local anesthetic systemic toxicity (LAST) is a potentially life-threatening complication of local anesthetic administration. In this article, the results of the Australian and New Zealand Registry of Regional Anaesthesia were analyzed to determine if ultrasound-guided peripheral nerve blockade (PNB) was associated with a reduced risk of LAST compared with techniques not utilizing ultrasound technology. Methods The period of study for this multicenter study involving 20 hospitals was from January 2007 through May 2012. The primary outcome was LAST comprising minor, major, and cardiac arrest (due to toxicity) events determined using standardized definitions. Multivariable logistic regression models and propensity score analyses were used to determine significant event predictors. Results The study population comprised 20,021 patients who received 25,336 PNBs. There were 22 episodes of LAST, resulting in an incidence of LAST of 0.87 per 1000 PNBs (95% confidence interval, 0.54–1.3 per 1000). Ultrasound guidance was associated with a reduced incidence of local anesthetic toxicity. Site of injection, local anesthetic type, dose per weight, dose, and patient weight were all predictors of LAST. Conclusions This study provides the strongest evidence, to date, that ultrasound guidance may improve safety because it is associated with a reduced risk of LAST following PNB.

Ultrasound-Guided Continuous Oblique Subcostal Transversus Abdominis Plane Blockade Description of Anatomy and Clinical Technique

Background: Recently, ultrasound-guided transversus abdominis plane blockade for abdominal wall analgesia has been described, and it involves injection of local anesthetic into the transversus abdominis plane. The posterior approach involves injection of local anesthetic in the lateral abdominal wall between the costal margin and the iliac crest and is suitable for postoperative analgesia after surgery below the umbilicus. The subcostal approach is suitable after abdominal surgery in the periumbilical region. The subcostal block can be modified, and the needle can be introduced along the oblique subcostal line from the xyphoid process toward the anterior part of the iliac crest. Objective: The purpose of this brief technical report was to describe in detail the anatomy and the technique of continuous oblique subcostal blockade. The goal of this approach was to produce a wider sensory blockade suitable for analgesia after surgery both superior and inferior to the umbilicus. Conclusions: 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.

Spread of injectate after ultrasound-guided subcostal transversus abdominis plane block: a cadaveric study

Ultrasound‐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]) cm2 using the single‐injection technique and 90 (85–96 [72–136]) cm2, 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.

Acute compartment syndrome of the lower limb and the effect of postoperative analgesia on diagnosis

Acute compartment syndrome can cause significant disability if not treated early, but the diagnosis is challenging. This systematic review examines whether modern acute pain management techniques contribute to delayed diagnosis. A total of 28 case reports and case series were identified which referred to the influence of analgesic technique on the diagnosis of compartment syndrome, of which 23 discussed epidural analgesia. In 32 of 35 patients, classic signs and symptoms of compartment syndrome were present in the presence of epidural analgesia, including 18 patients with documented breakthrough pain. There were no randomized controlled trials or outcome-based comparative trials available to include in the review. Pain is often described as the cardinal symptom of compartment syndrome, but many authors consider it unreliable. Physical examination is also unreliable for diagnosis. There is no convincing evidence that patient-controlled analgesia opioids or regional analgesia delay the diagnosis of compartment syndrome provided patients are adequately monitored. Regardless of the type of analgesia used, a high index of clinical suspicion, ongoing assessment of patients, and compartment pressure measurement are essential for early diagnosis.

Continuous femoral nerve blockade or epidural analgesia after total knee replacement : A prospective randomized controlled trial

Because postoperative pain after total knee replacement (TKR) can be severe, we compared the analgesic efficacy of continuous femoral nerve blockade (CFNB) and continuous epidural analgesia (CEA) after TKR in this prospective randomized trial. Patients undergoing TKR under spinal anesthesia were randomized to receive either a femoral infusion of bupivacaine 0.2% (median infusion rate 9.3 mL/h) (n = 53) or an epidural infusion of ropivacaine 0.2% with fentanyl 4 &mgr;g/mL (median infusion rate 7.6 mL/h) (n = 55). Adjuvant analgesics were oral rofecoxib and oxycodone and IV morphine. Pain, nausea and vomiting, hypotensive episodes, motor block, range of knee movement, and rehabilitation milestones were assessed postoperatively. There were equivalent pain scores, range of movement, and rehabilitation in both groups. There was significantly less nausea and vomiting in the CFNB group (P < 0.002). The CFNB group received more rofecoxib (P < 0.04) and oxycodone (P < 0.005) than the CEA group. The operative limb displayed more motor block than the nonoperative limb in both groups at the level of the hip and knee for up to 48 h (P < 0.05, Mann-Whitney U-test), but there was no difference between groups in the nonoperative limb. CFNB is an effective regional component of a multimodal analgesic strategy after TKR.

Ultrasound-guided thoracic paravertebral blockade: a cadaveric study.

BACKGROUND: Multiple approaches to the paravertebral space have been described to produce analgesia after thoracic surgery. Ultrasound-guided regional anesthesia has the potential to improve efficacy and reduce complications via real-time visualization of the paravertebral space, surrounding structures, and the approaching needle. We compared a single- versus dual-injection technique for ultrasound-guided paravertebral blockade in a cadaver model, evaluating the spread of contrast dye and location of a catheter. METHODS: Thirty paravertebral injections and 20 catheter placements were performed on 10 fresh cadavers. The paravertebral space was identified using an ultrasound probe in the transverse plane using a linear transducer. An in-plane needle approach was used. Using analine contrast dye, a single 20-mL injection at T6-7 on one side and a dual-injection technique of 10 mL at T3-4 and T7-8 on the contralateral side were performed on each cadaver, followed by insertion of a catheter through the needle. The cadaver was then dissected to evaluate spread of contrast dye and catheter location. RESULTS: The paravertebral space was easily identified with ultrasound on each cadaver. Contrast dye was seen to surround somatic and sympathetic nerves in the paravertebral, intercostal, and epidural spaces. Contrast dye was present in 19 of 20 paravertebral spaces over 3 to 4 segments (range, 0–10) with no significant differences between single- and dual-injection techniques. Contrast dye spread more extensively across intercostal segments with 4.5 spaces (range, 2–10) covered with a single injection and 6 spaces (range, 2–8) covered with a dual-injection technique (P = 0.03). There was epidural spread of contrast in 40% of paravertebral injections in both single- and dual-injection techniques. Catheters were located in the paravertebral space (60%), prevertebral space (20%), and epidural space (5%). CONCLUSIONS: Transverse in-plane ultrasound-guided needle insertion into the thoracic paravertebral space is both feasible and reliable. However, paravertebral spread of contrast is highly variable with intercostal and epidural spread likely contributing significantly to the analgesic efficacy. A dual-injection technique at separate levels seems to cover more thoracic dermatomes because of greater segmental intercostal spread (rather than paravertebral spread) than a single-injection approach. Catheters are located in nonideal positions in 40% of cases using this in-plane technique.

The Second ASRA Practice Advisory on Neurologic Complications Associated With Regional Anesthesia and Pain Medicine: Executive Summary 2015.

Neurologic injury associated with regional anesthetic or pain medicine procedures is extremely rare. The Second American Society of Regional Anesthesia and Pain Medicine Practice Advisory on Neurologic Complications Associated With Regional Anesthesia and Pain Medicine focuses on those complications associated with mechanical, ischemic, or neurotoxic injury of the neuraxis or peripheral nervous system. As with the first advisory, this iteration does not focus on hemorrhagic or infectious complications or local anesthetic systemic toxicity, all of which are the subjects of separate practice advisories. The current advisory offers recommendations to aid in the understanding and potential limitation of rare neurologic complications that may arise during the practice of regional anesthesia and/or interventional pain medicine. What’s New The Second American Society of Regional Anesthesia and Pain Medicine Practice Advisory on Neurologic Complications Associated With Regional Anesthesia and Pain Medicine updates information that was originally presented at the Society’s first open forum on this subject (2005) and published in 2008. Portions of the second advisory were presented in an open forum (2012) and are herein updated, with attention to those topics subject to evolving knowledge since the first and second advisory conferences. The second advisory briefly summarizes recommendations that have not changed substantially. New to this iteration of the advisory is information related to the risk of nerve injury inherent to common orthopedic surgical procedures. Recommendations are expanded regarding the preventive role of various monitoring technologies such as ultrasound guidance and injection pressure monitoring. New clinical recommendations focus on emerging concerns including spinal stenosis and vertebral canal pathologies, blood pressure management during neuraxial anesthesia, administering blocks in anesthetized or deeply sedated patients, patients with preexisting neurologic disease, and inflammatory neuropathies. An updated diagnostic and treatment algorithm is presented.