Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Mar 2010
Ultrasonographic appearance of intraneural injections in the porcine model.
Ultrasonographic (US) images of apparent intraneural injection of local anesthetic solutions have been reported. We aimed to define US signs of intraneural (ie, subepineural) injection using a histologic standard in an animal model and compare these signs with other potential markers of intraneural injection, including low nerve stimulation current thresholds and high injection pressures. ⋯ Ultrasonographic images compatible with nerve swelling during an injection are consistent with true intraneural injections as demonstrated by histologic analysis. Under the conditions studied, intensity of the stimulating current required to elicit motor response was not associated with intraneural needle placement. In the absence of fascicular injury, intraneural injections were associated with low injection pressure, although false-positive results can occur.