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Blood Bupivacaine Concentrations After Transversus Abdominis Plane Block in Neonates: A Prospective Observational Study

Suresh, Santhanam MD; De Oliveira, Gildasio S. Jr. MD, MSCI

doi: 10.1213/ANE.0000000000001088
Pediatric Anesthesiology: Research Report

BACKGROUND: Untreated pain can have instant and prolonged consequences to behavioral and neurologic outcomes in neonates. Although the use of transversus abdominis plane (TAP) block to minimize postsurgical pain has been demonstrated in neonates, no data regarding the safety of this procedure are available for this patient population. For instance, it is unknown whether plasma levels of local anesthetics are safe in neonates after TAP blocks. The main objective of the current investigation was to evaluate plasma bupivacaine concentrations in neonates having an ultrasound-guided TAP block.

METHODS: The study was a prospective, observational study. After general anesthesia was induced, neonates received an ultrasound-guided TAP block with 0.125% bupivacaine and a total volume of 1 mL/kg. Dried blood spot samples were obtained and analyzed for bupivacaine levels at 0, 5, 15, 30, 60, 120 minutes, 4, and 24 hours after the TAP block.

RESULTS: Ten neonates were included in the study. The highest 99% upper prediction limit for blood concentration, 0.38 µg/mL, occurred at the 30-minute interval, but it was significantly lower than potentially toxic plasma levels (1.5–2.0 µg/mL). The highest individual concentration was 0.26 µg/mL and occurred at the 30-minute interval. None of the patients demonstrated any potential signs of local anesthetic toxicity.

CONCLUSIONS: Our results suggest a low risk of local anesthetic toxicity in neonates after a TAP block. Future studies to determine the efficacy of the TAP block to minimize postsurgical pain in this patient population are warranted.

Published ahead of print November 17, 2015

From the *Department of Pediatric Anesthesia, Ann & Robert H. Lurie Children’s Hospital of Chicago, Northwestern University, Chicago, Illinois; and Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.

Accepted for publication September 15, 2015.

Published ahead of print November 17, 2015

Funding: Ann & Robert H. Lurie Children’s Hospital of Chicago.

The authors declare no conflicts of interest.

Reprints will not be available from the authors.

Address correspondence to Gildasio S. De Oliveira, Jr., MD, MSCI, Department of Anesthesiology, Northwestern University, 241 East Huron St. F5-704, Chicago, IL 60611. Address e-mail to

© 2016 International Anesthesia Research Society