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Background: Variation of local anesthetic dosing has been reported for adult peripheral nerve blocks (PNBs) and infant caudal blocks. As higher doses of local anesthetics (LA) are potentially associated with increased risk of complications (eg, local anesthetic systemic toxicity), it is important to understand the source of LA dose variation. Using the Pediatric Regional Anesthesia Network (PRAN) database, we aimed to determine if variation in dosing exists in pediatric single-injection PNBs, and what factors influence that variation.The primary aim of this study was to determine the factors associated with dosing for the 10 most commonly performed PNBs, with the secondary aim of exploring possible factors for variation such as number of blocks performed versus geographic location., Methods: The PRAN database was used to determine the 10 most common pediatric PNBs, excluding neuraxial regional anesthetics. The 10 most common pediatric PNBs in the PRAN database were analyzed for variation of LA dose and causes for variation., Results: In a cohort of 34 514 children receiving PNBs, the mean age was 10.38 (+/-5.23) years, average weight was 44.88 (+/-26.66) kg and 61.8% were men. The mean bupivacaine equivalent (BE) dose was 0.86 (+/-0.5) mg kg -1 and ropivacaine was used in 65.4% of blocks. Dose decreases with age (estimate -0.016 (-0.017, -0.015; p<0.001)). In all blocks for all age groups, the range of doses that make up the central 80% of all doses exceeds the mean BE dose for the block. Variation is not related to the number blocks performed at an institution (p=0.33 (CI -0.42 to 0.15)). The dose administered for a PNB is driven in order of impact by the institution where the block was performed (Cohen's ƒ=0.45), then by weight (0.31), type of block (0.27), LA used (0.15) and age (0.03)., Conclusions: Considerable variation in dosing exists in all age groups and in all block types. The most impactful driver of local anesthetic dose is the institution where the block was performed, indicating the dosing of a potentially lethal drug is more based on local culture than on evidence., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The aim of this article was to provide a detailed description of the neonatal anatomy related to the erector spinae plane block and to report the spread of the dye within the fascial planes and potential dermatomal coverage., Methods: Using ultrasound guidance, the bony landmarks and anatomy of the erector spinae fascial plane space were identified. The erector spinae plane block was then replicated unilaterally in two fresh unembalmed neonatal cadavers. Using methylene blue dye, the block was performed at vertebral levels T5-using 0.5 mL in cadaver 1-and T8-using 0.2 mL in cadaver 2. The craniocaudal spread of dye was tracked within the space on the ultrasound screen and further confirmed on dissection., Results: Craniocaudal spread was noted from vertebral levels T3 to T6 when the dye was introduced at vertebral level T5 and from vertebral levels T7 to T11 when the dye was introduced at vertebral level T8. Furthermore, the methylene blue spread was found anteriorly in the paravertebral and epidural spaces, staining both the dorsal and ventral rami of the spinal nerves T2 to T12. Small amounts of dye were also found in the intercostal spaces., Conclusion: In two neonatal fresh cadavers, the dye was found to spread to multiple levels and key anatomic locations., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Objectives: The impact of the patient state at time of placement of regional blocks on the risk of complications is unknown. Current opinion is based almost entirely on case reports, despite considerable interest in the question. Analyzing more than 50,000 pediatric regional anesthesia blocks from an observational prospective database, we determined the rate of adverse events in relation to the patient's state at the time of block placement. Primary outcomes considered were postoperative neurologic symptoms (PONSs) and local anesthetic systemic toxicity (LAST). Secondary outcome was extended hospital stay due to a block complication., Methods: The Pediatric Regional Anesthesia Network is a multi-institutional research consortium that was created with an emphasis on rigorous, prospective, and complete data collection including a data validation and audit process. For the purpose of the analysis, blocks were divided in major groups by single injection versus continuous and by block location. Rates were determined in aggregate for these groups and classified further based on the patient's state (general anesthesia [GA] without neuromuscular blockade [NMB], GA with NMB, sedated, and awake) at the time of block placement., Results: Postoperative neurological symptoms occurred at a rate of 0.93/1000 (confidence interval [CI], 0.7-1.2) under GA and 6.82/1000 (CI, 4.2-10.5) in sedated and awake patients. The only occurrence of PONSs lasting longer than 6 months (PONSs-L) was a small sensory deficit in a sedated patient (0.019/1000 [CI, 0-0.1] for all, 0.48/1000 [CI, 0.1-2.7] for sedated patients). There were no cases of paralysis. There were 5 cases of LAST or 0.09/1000 (CI, 0.03-0.21). The incidence of LAST in patients under GA (both with and without NMB) was 0.08/1000 (CI, 0.02-0.2) and 0.34/1000 (CI, 0-1.9) in awake/sedated patients. Extended hospital stays were described 18 times (0.33/1000 [CI, 0.2-0.53]). The rate for patients under GA without NMB was 0.29/1000 (CI, 0.13-0.48); GA with NMB, 0.29/1000 (CI, 0.06-0.84); sedated, 1.47/1000 (CI, 0.3-4.3); and awake, 1.15/1000 (CI, 0.02-6.4)., Conclusions: The placement of regional anesthetic blocks in pediatric patients under GA is as safe as placement in sedated and awake children. Our results provide the first prospective evidence for the pediatric anesthesia community that the practice of placing blocks in anesthetized patients should be considered safe and should remain the prevailing standard of care. Prohibitive recommendations based on anecdote and case reports cannot be supported.