Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine
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Injection of air under ultrasound guidance via a perineural catheter after insertion ("air test") has been described as a means to infer placement accuracy, yet this test has never been rigorously evaluated. We tested the hypothesis that the air test predicts accurate catheter location greater than chance and determined the test's sensitivity, specificity, and positive and negative predictive values using a porcine-bovine model and blinded expert in ultrasound-guided regional anesthesia. The air test improved the expert clinician's assessment of catheter tip position compared to chance, but there was no difference when compared to direct visualization of the catheter without air injection.
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In sonographic evaluations of peripheral nerves, the healthy, contralateral side may be used as an internal control for the pathologic one. Therefore, the inherent side-to-side differences must be minimal. The goal of this study was to determine the reliability of side-to-side measurements of upper extremity nerves in healthy volunteers. ⋯ In general, the healthy contralateral side can be used as an internal control considering that changes in minimum detectable differences are related to the anatomic site considered.