Intraneural and Perineural Inflammatory Changes in Piglets After Injection of Ultrasound Gel, Endotoxin, 0.9% NaCl, or Needle Insertion without Injection

Pintaric, Tatjana Stopar MD, PhD, DEAA*; Cvetko, Erika DMD, PhD; Strbenc, Malan DVM, PhD; Mis, Katarina PhD§; Podpecan, Ozbalt DVM, PhD; Mars, Tomaz MD, PhD§; Hadzic, Admir MD, PhD

doi: 10.1213/ANE.0000000000000142
Regional Anesthesia: Brief Report

BACKGROUND: Ultrasound gel nerve inflammation has been reported. We evaluated the extent and nature of inflammation after gel injection with endotoxin (positive), saline, or dry needle puncture (negative) controls after peripheral blocks in piglets.

METHODS: Selected nerves of 12 piglets were localized by landmarks and nerve stimulator. Forty-eight hours after injection, specimens were examined for immunohistochemical cell differentiation/quantification and cytokine expression by using quantitative polymerase chain reaction.

RESULTS: Both gel and endotoxin injections resulted in a significantly higher density of inflammatory cells (lymphocytes/granulocytes) as compared with needle insertions and/or saline injections (both P < 0.001). Cytokines were not detected in any of the specimens.

CONCLUSIONS: Perineural gel injections cause significant inflammation. The lack of cytokines suggests injectate-related changes rather than mechanical trauma.

From the *Clinical Department of Anesthesiology and Intensive Therapy, University Medical Center Ljubljana, Ljubljana, Slovenia; Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; Bia Ltd. Ljubljana, Slovenia; §Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; Savinian Veterinary Polyclinic, Zalec, Slovenia; and College of Physicians and Surgeons, Columbia University, New York, New York.

Accepted for publication January 8, 2014.

Funding: This work was funded by the Slovenian Research Agency (P3-0043-0381) and the tertiary funding of the Clinical Department of Anesthesia and Intensive Therapy, University Medical Center Ljubljana.

Conflict of Interest: See Disclosures at the end of the article.

Reprints will not be available from the authors.

Address correspondence to Tatjana Stopar Pintaric, MD, PhD, DEAA, Clinical Department of Anesthesiology and Intensive Therapy, University Medical Center Ljubljana, Zaloska 7, 1000 Ljubljana, Slovenia. Address e-mail to tatjanas38@gmail.com.

© 2014 International Anesthesia Research Society