Ultrasound visibility of needles used for regional nerve block: An in vitro study

Randomized, prospective, observational simulation study comparing residents' needle-guided vs free-hand ultrasound techniques for central venous catheter access

BACKGROUND

Short-axis ultrasound-guided placement of central venous catheters (CVCs) is widely accepted as safe practice. However, utilizing the long-axis approach could further improve safety, as it allows for better visualization of the needle as it is advanced to the target vessel. However, the long-axis approach has not widely been used due to the technical difficulty. Recently, a new needle guidance device has become available to aid in the long-axis approach. We hypothesized that the use of a needle guide paired with the long-axis approach would facilitate puncture of the target vessel in a simulation model more effectively than similar free-hand techniques.

METHODS

A prospective observational study of anaesthesia residents using a CVC partial-task training device was conducted. Each resident performed needle puncture of the target vessel with three different techniques, assigned in random order: short-axis free hand (S-FH), long-axis free hand (L-FH), and long-axis needle guide (NG). To prove the effectiveness of the needle guide, the fraction of time the needle tip remained in view of the ultrasound was recorded and compared. Time required for completing the task and the number of needle sticks and needle re-directions were compared.

RESULTS

Thirty-three residents participated in the study. The fraction of time the needle tip remained in view of the ultrasound was significantly higher for the residents using NG [0.90 (0.10)] compared with residents using the other techniques [L-FH: 0.36 (0.20), S-FH: 0.18 (0.10)] (P<0.001). For each resident, the use of the needle guide in the long-axis approach increased visualization by 352 (276)% compared with that of L-FH and by 1028 (1804) % compared with that of S-FH. There was no significant difference in time required to puncture the target between NG [23.7 (14.6) s] and L-FH [30.3 (36.5) s] (P=0.21); however, both were significantly longer than S-FH [17.0 (13.3) s] (P=0.012). The numbers of needle sticks and of needle re-directions did not differ among the groups.

CONCLUSIONS

The needle guide device used in the long-axis approach improved the needle visualization compared with free-hand techniques. The needle guide used in the long-axis technique, however, did not facilitate puncture of the target vessel in this simulation model when compared with free-hand techniques.

Two-Dimensional Mapping to Assess Direction and Magnitude of Needle Tip Error in Ultrasound-Guided Regional Anaesthesia

We assessed whether echogenic needles reduce tip location error, by comparing three echogenic designs (Pajunk Sonoplex, Lifetech, B. Braun Stimuplex D+) with a non-echogenic control (Pajunk Uniplex), using a novel assessment technique in unembalmed human cadavers. Multiple images were taken of each needle at shallow (15 to 25°), moderate (35 to 45°) and steep (55 to 65°) insertion angles. Twenty anaesthetists with varied experience in ultrasound-guided nerve blocks identified needle tip position and stated their confidence level in estimates. Actual tip position was determined at the time of image generation but concealed from the anaesthetists. Two-dimensional mapping of ‘tip-error’ involved measurement of the distance and orientation of each clinician's estimate of tip position in relation to the actual tip position. There were no significant differences in confidence or overall needle visibility at shallow insertion angles. At steeper angles, the Sonoplex showed significantly higher confidence and visibility scores. The remaining echogenic designs did not show any significant differences from the non-echogenic control. Objective measurements of tip error followed the same pattern as the subjective data, although were not universally significant. Two-dimensional mapping showed that as needle visibility deteriorated, so precise tip location was lost but the needle shaft/insertion path remained well-identified. As visibility deteriorated further, accuracy in this axis was also lost. When inaccurate, clinicians generally assessed the needle tip to be more superficial and inserted less far than it actually was. This has important implications for the safety of ultrasound-guided regional anaesthesia. Effective echogenic needle technology has the potential to address these concerns.

Comparison of ultrasound-guided biopsy technique for thyroid nodules with respect to adequacy of cytological material

BACKGROUND

Ultrasound-guided fine-needle aspiration cytology (FNAC) sampling of the thyroid represents a standard diagnostic procedure in the evaluation of thyroid nodules. The specimen can be acquired using either of two different techniques. In the first, the short axis is used with observation only of the tip of the needle whilst in the nodule. In the second technique, the long axis is used with the observation of the entire length of the needle. The decision to sample utilizing either technique was done randomly. This study is a retrospective review performed to compare these two techniques with regard to specimen adequacy.

METHODS

Ultrasound-guided FNACs were performed in 80 thyroid nodules between May 2008 and February 2009. One physician acquired the cytology specimens using one of these two methods after localization. Data on the type of technique and its diagnostic accuracy were collected.

RESULTS

Forty-nine of 80 thyroid nodules were sampled using the long-axis technique. The overall and deep-lesion diagnostic adequacies of specimens were significantly higher using this technique (93.9 and 95.1%, respectively, p < 0.01) than the short-axis technique. When comparing the long and short axes for superficial lesions, there was no significant difference in adequacy of the samples (p = 0.92).

CONCLUSIONS

This is the first study to compare long- and short-axis techniques with regard to specimen adequacy for thyroid nodules. The long-axis technique decreased the rate of inadequate material and provided more accurate cytological evaluation for deeper lesions.

The optimal volume of 0.2% ropivacaine required for an ultrasound-guided stellate ganglion block

BACKGROUND

This study was performed to find the optimal volume of local anesthetics needed for a successful ultrasound-guided stellate ganglion block (SGB) to treat head and neck pathology.

METHODS

Fifteen female and fourteen male sensory-neural hearing loss patients received 4 times SGBs with 0.2% ropivacaine in volumes of 6, 4, 3 and 2 ml at 1 to 3 day intervals. Using the transverse short-axis view of the neck that showed Chassaignac's tubercle at the C6 level, a 25-gauge, and 4 cm needle was inserted via the lateral paracarotid approach with out-of-plane targeting between the prevertebral fascia and the ventral surface of longus colli muscle (subfascial injection). A successful block was confirmed with the onset of ptosis (Horner's syndrome).

RESULTS

There were no significant statistical differences between the presence of Horner's syndrome and the volume of local anesthetics given. However, Horner's syndrome was present in all trials for the 4 ml and 6 ml groups. Six (20.7%) and three out (10.4%) of twenty-nine trials in the 2 ml and 3 ml groups, respectively, failed to elicit Horner's syndrome. The duration of action was significantly different in the 2 ml group compared to that of the 6 ml group, but there was no significant difference between the other groups, including the 4 ml vs. 6 ml groups. The side effects were not different between the groups.

CONCLUSIONS

This data suggests that the optimal volume of 0.2% ropivacaine for ultrasound-guided SGB to treat the head and neck pathology in daily practice is 4 ml.

The learning process of the hydrolocalization technique performed during ultrasound-guided regional anesthesia

BACKGROUND

Because poor echogenicity of the needle remains a safety issue, we decided to analyze the learning process of the hydrolocalization technique (Hloc) performed to continuously identify needle-tip anatomical position during many ultrasound-guided regional anesthesia procedures.

METHODS

Ten senior anesthesiologists naïve to the Hloc agreed to participate in the study. They were requested to perform 40 out-of-plane (OOP) approach ultrasound-guided axillary blocks (AB) each using the Hloc. The Hloc, which is a needle-tip localization principle, was performed by means of repetitive injections of a small amount of a local anesthetic solution (0.5-1 ml) under an ultrasound beam. Details of the learning process and skill acquisition of the Hloc were derived from the following parameters: the duration of block placement, a measure of the perceived difficulty of needle-tip visualization, a measure of block placement difficulty, and the amount of local anesthetics solution required for the technique.

RESULTS

Four hundred ABs were performed. The success rate of an ultrasound-guided AB was 98%. The Hloc was successful in all patients. Skill acquisition over time of the Hloc was associated with a significant reduction of both the duration and the perceived difficulty of ABs placement. Apprenticeship data revealed that 20 blocks were required to successfully place AB within 5 min in most cases using the Hloc.

CONCLUSION

The Hloc performed during the OOP approach of ultrasound-guided regional anesthesia is a simple technique with a relatively short learning process feasible for efficient placement of ABs.

Photoacoustic imaging of clinical metal needles in tissue

The ability to visualize and track temporarily or permanently implanted metal devices is important in many applications ranging from diagnosis to therapy. Specifically, reliable imaging of metal needles is required in today's clinical settings. Currently, ultrasound is utilized to image a needle inserted into tissue in real time. However, the diagnostic value and tracking ability of these images depends highly on the orientation of the needle, and also its proximity to regions of interest in the tissue. We examine the use of photoacoustic imaging combined with current ultrasound imaging methods to obtain high-contrast images of commonly used needles in the body. Experiments were performed using 21 G and 30 G needles inserted into ex vivo porcine tissue and tissue-mimicking phantoms. The needles and surrounding tissue were imaged using an ultrasound imaging system interfaced with the pulsed laser source necessary for photoacoustic imaging. The results suggest that photoacoustic imaging, combined with ultrasound imaging, is capable of real-time, high-contrast, and high-spatial-resolution visualization of metal implants within anatomical landmarks of the background tissue.

Ultrasound and nerve stimulation-guided L5 nerve root block

STUDY DESIGN

Case series.

OBJECTIVE

Evaluation of ultrasound and nerve stimulation-guided L5 nerve root block technique.

SUMMARY OF BACKGROUND DATA

Ultrasound-guided peripheral nerve block has become clinically applied. However, selective lumbosacral nerve root block is conducted under radiographic guidance, which involves patients and operators being exposed to radiation. In addition, it cannot be carried out easily during outpatient visits or at the bedside. We conducted L5 nerve root block, which is one of the most common lumbosacral nerve root block under ultrasonic guidance, using electrical nerve stimulation.

METHODS

We assessed the effectiveness of ultrasound and nerve stimulation-guided L5 nerve root block on 78 patients with L5 radicular syndrome. To compare ultrasonic guidance using electrical nerve stimulation with radiographic guidance, we used a contrast agent and assessed its distribution.

RESULTS

After nerve block, decreased sensation at L5 neural region and diminished/fully resolved pain was observed in all patients except for 3 in whom nerve block could not be conducted as their articular process protruded laterally. Concerning the response to stimulation, all except for these 3 felt the tapping sensation at their L5 neural regions, but no contraction of muscles was observed. The number of patients who showed an extraneural, paraneural, and intraneural pattern on contrast radiography was 71, 4, and 0, respectively.

CONCLUSION

Ultrasound-guided L5 nerve root block using electrical nerve stimulation is a safe and effective method.

[Portable ultrasound devices in regional anesthesia: the brachial plexus block]

Ultrasonography has received increasing attention in regional anesthesia in recent years because it allows visualization of the nerves, the needle, and the surrounding structures and makes it possible to monitor distribution of the local anesthetic. Ultrasound technology is unfamiliar to most anesthesiologists, unless they work with transesophageal echocardiography. Ultrasound-guided regional anesthesia relies entirely on the expertise of the person performing the technique and how that person interprets the images, though the latest portable ultrasound devices are ergonomically designed for fast, easy use, even by less experienced personnel. The high-frequency probes can identify the brachial plexus and produce excellent images of considerable educational value that differ only slightly from those provided by larger, more expensive equipment. Ultrasonography makes it possible to identify the brachial plexus, from the roots to the peripheral nerves of the arm. We describe the main approaches used in providing an ultrasound-guided brachial plexus block and explain the basic principles of ultrasound imaging.

Toward an ultrasound curriculum for critical care medicine

Accurate assessment and rapid decision-making are essential to save lives and improve performance in critical care medicine. Real-time point-of-care ultrasound has become an invaluable adjunct to the clinical evaluation of critically ill and injured patients both for pre- and in-hospital situations. However, a high level of quality is necessary, guaranteed by appropriate education, experience, credentialing, quality control, continuing education, and professional development. Although educational recommendations have been proposed by a variety of nonimaging specialties, to date they are still scattered and limited examples of standards for critical and intensive care professionals. The challenge of providing adequate specialty-specific training, as encouraged by major medical societies, is made even more difficult by the diversity of critical care ultrasound utilization by various subspecialties in a variety of settings and numerous countries. In order to meet this educational challenge, a standard core curriculum is presented in this manuscript. The proposed curriculum is built on a competence, performance, and outcomes-based approach that is tailored to setting-specific training needs and prioritized according to critical problem-based pathways, rather than traditional organ-based systems. A multiple goal-oriented style fully addresses the specialty-specific approach of critical and intensive care professionals, who typically deal with disease states in complex scenarios rather than individual organ complaints. Because of the variation in the concept of what constitutes critical care worldwide, and the rate of change of information and technology, this manuscript attempts to present a learning system addressing a variety of needs for a rapidly changing world.

Ultrasound-guided peripheral nerve blockade

Peripheral nerve blockade (PNB) for orthopedic surgery is usually performed without visual guidance, relying mainly on surface anatomic landmarks and electrical stimulation to localize nerves. Moreover, multiple trial and error attempts to place a needle can frustrate the operator, cause unwarranted pain to the patient, and waste valuable time in the operating room. Inaccurate needle placement and spread of local anesthetic account for most PNB failures, whereas "trial and error" needle manipulations for nerve localization can cause complications. The recent application of ultrasound (US) to PNB affords real-time imaging of the target nerve, needle, and surrounding vasculature, such that needle proximity to the nerve is ensured and vascular puncture avoided. This article reviews the advantages, principles, and techniques of US for the most common types of PNB.

Ultrasound guidance for ilioinguinal/iliohypogastric nerve block: a pilot study

BACKGROUND

Ilioinguinal/iliohypogastric nerve block combined with general anaesthesia facilitates inguinal herniorrhaphy in an ambulatory setting by improving analgesia and reducing opioid requirements. Case reports in children indicate the possibility of colonic puncture and associated morbidity with blind ilioinguinal and iliohypogastric blockade.

AIMS

To investigate the feasibility of ultrasound guided ilioinguinal/iliohypogastric nerve block.

METHODS

Pilot study of four patients where ultrasound imaging was used to identify the ASIS, anterior abdominal muscle layers, the peritoneum and to guide local anaesthetic infiltration in patients undergoing inguinal hernia surgery and appendicectomy.

RESULTS

All patients had successful blocks, without complications. Mean visual analogue scores were 2/10 in the post anaesthesia care unit. Mean opioid consumption was 10 mg of intramuscular morphine in the first 24 h.

CONCLUSIONS

Ultrasound guidance for ilioinguinal and iliohypogastric nerve block in the inguinal region is both feasible and a promising technique.