Evaluation of a Novel Out-of-Plane Needle Guide

Most ultrasound-guided regional procedures use an in-plane approach. Out-of-plane approaches may be desirable in some situations but can be difficult because of an inability to visualize the needle until it intersects the plane of the ultrasonic beam. Here we present a novel out-of-plane needle guide, using a retreating depth stop, and compare its performance with unguided in-plane and out-of-plane techniques.

First- and third-year medical students with no or minimal ultrasound experience were recruited for the study. After a brief training session on in-plane and out-of-plane needling techniques, as well as use of the retreating-stop needle guide, they attempted to place a needle as close as possible to a target embedded in porcine tissue. The total time to complete the procedure was measured. Accuracy was measured by a skilled sonographer, who identified the needle tip and measured the distance to the target. The data were tested for significance using an analysis of variance.

The mean total time spent differed significantly between groups (novel needle guide, 34 seconds; in-plane, 120 seconds; out-of-plane, 113 seconds; P = .021). Needle proximity was on average more accurate with the needle guide, although this difference was not statistically significant (novel needle guide, 8 mm; in-plane, 15 mm; out-of-plane, 14 mm; P = .289).

In relatively inexperienced sonographers, the retreating-stop needle guide reduced the procedure time compared with in-plane and out-of-plane techniques. No significant changes in needling accuracy were observed.