The new technological trends in ultrasound-guided regional anesthesia. Curr Opin Anaesthesiol. 2013;Aug 13; Epub ahead of print. [PMID: 23945198 DOI: 10.1097/01.aco.0000432512.15694.dd]

Needle tip tracking for ultrasound-guided peripheral nerve block procedures-An observer blinded, randomised, controlled, crossover study on a phantom model

BACKGROUND

The Onvision needle tip tracking (NTT) is a new technology consisting of a needle with an ultrasound sensor close to the needle tip and a console for computerised signal processing. The aim of the study was to evaluate NTT technology during ultrasound-guided simulated peripheral nerve block procedures in a porcine phantom model.

METHODS

Forty anaesthesiologists performed in-plane and out-of-plane simulated nerve blocks with and without NTT guidance. The primary outcome measure was procedure time. Secondary outcomes were hand movements and the path length travelled by the hands measured by motion analysis, precision of the needle tip related to the target structure, success rates and violations of the target structure, and the participants confidence whether their procedure would be successful or not.

RESULTS

Procedure time was reduced from 66.7 (SD = 47.5) seconds to 43.8 (SD = 29.2) seconds when NTT was used for out-of-plane procedures (P = 0.002). The number of hand movements of the probe hand was 13.9 (SD = 30.2) with NTT and 22.8 (SD = 30.0) without NTT (P = 0.019). No significant differences were registered during the performance of in-plane procedures. The participants confidence in a presumed block success was increased with both in-plane procedures (8.50 (SD = 1.18) with NTT vs 7.65 (SD = 1.96), P = 0.004) and out-of-plane procedures (8.50 (SD = 1.09) vs 7.10 (SD = 1.89), P = 0.0001).

CONCLUSIONS

The new NTT technology significantly reduced the procedure time and the number of hand movements for ultrasound-guided out-of-plane PNB procedures. No significant differences were found for the in-plane procedures.

Recent technological advancements in regional anesthesia

Just two decades ago, regional anesthesia was performed blindly with dubious outcomes and little support from surgeons and patients. Technological advances in regional anesthesia have revolutionized techniques and largely improved outcomes. Ultrasound (US) technology continues to advance and has become more affordable. Improvements have come in the form of picture quality, resolution, portability, and smaller equipment. The US technology can identify otherwise unrecognized pathology and can help to optimize patient flow by allowing for more accurate triage and effective treatments and providing timelier interventions. In recent years, several different strategies to help improve and ease US-guided needle identification and placement have been developed, including magnetically guided needle US technology. Three-dimensional (3D) and four-dimensional (4D) US use is another potential way to help improve first-pass success and limit patient harm for regional anesthetics. The advent of echogenic needles and the resulting improvement in needle visualization under US has had a positive impact on physician comfort in performing regional anesthesia and on visualization time of the needle during US-guided procedures. To reduce variability and to reduce the anesthesiologist's workload, the use of robots in regional anesthesia has been assessed in recent years. Peripheral nerve stimulation (PNS) has also demonstrated efficacy in acute and chronic pain settings. Additional research and randomized controlled trials are necessary to evaluate novel technologies.

Evaluation of a Novel Out-of-Plane Needle Guide

OBJECTIVES

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

[Seeing more : Technical innovations in regional anesthesia]

Visualization and verification are key factors since the implementation of ultrasound-guided regional anesthesia. This article reviews and discusses newer technical innovations in regional anesthesia with regard to optimization of needle guidance, improvements in needle visibility, technical improvements in ultrasound techniques and innovative technologies in regional anesthesia. Clinically available applications are presented as well as experimental tools and techniques with a potential for clinical implementation in the future. Mechanical needle guides are used to improve alignment of needle axis and ultrasound beam axis. Compound imaging technology improves needle visibility in steep needle insertion angles and is already implemented in daily clinical practice. Sonoelastography improves tissue discrimination and detection of small amounts of fluids. Benefits of 3D and 4D ultrasound in regional anesthesia are discussed as well as experimental tools for tissue discrimination, such as optical reflection spectrophotometry.

Perioperative pain control after total knee arthroplasty: An evidence based review of the role of peripheral nerve blocks

Over the last decades, the number of total knee arthroplasty procedures performed in the United States has been increasing dramatically. This very successful intervention, however, is associated with significant postoperative pain, and adequate postoperative analgesia is mandatory in order to allow for successful rehabilitation and recovery. The use of regional anesthesia and peripheral nerve blocks has facilitated and improved this goal. Many different approaches and techniques for peripheral nerve blockades, either landmark or, more recently, ultrasound guided have been described over the last decades. This includes but is not restricted to techniques discussed in this review. The introduction of ultrasound has improved many approaches to peripheral nerves either in success rate and/or time to block. Moreover, ultrasound has enhanced the safety of peripheral nerve blocks due to immediate needle visualization and as consequence needle guidance during the block. In contrast to patient controlled analgesia using opioids, patients with a regional anesthetic technique suffer from fewer adverse events and show higher patient satisfaction; this is important as hospital rankings and advertisement have become more common worldwide and many patients use these factors in order to choose a certain institution for a specific procedure. This review provides a short overview of currently used regional anesthetic and analgesic techniques focusing on related implications, considerations and outcomes.