Use of Continuous Electrical Impedance Measurement for Accurate Nerve Block in Rabbits

Objective To perform an effective and safe nerve block, the needle must be placed near the target nerve while avoiding nerve damage. Our objective was to conduct an animal study to determine whether changes in electrical impedance (EI) could be used to guide the needle and achieve a safe and accurate nerve block. Methods We measured the EI of rabbit tissues during ultrasound-guided sciatic nerve block using a bipolar needle via the in-plane needle approach. The EI values and needle track on the ultrasound monitor were video-recorded. When there was a change in the EI, the needle advancement was stopped, and a stained anesthetic was injected. Subsequently, the animals were euthanized, and the anesthetic-stained tissue was examined via dissection, while the other tissue was preserved at –80°C for microscopic analysis. Results The EI remained stable as the needle advanced through the muscle (extraneural); however, it markedly decreased when the needle tip contacted the nerve or slightly punctured the epineurium (paraneural). The mean extra- and paraneural EIs were 4.92 ± 1.31 kΩ (range, 2.39–9.67 kΩ) and 2.86 ± 0.96 kΩ (range, 1.66–5.13 kΩ), respectively. Examination of the dissections and cryostat sections showed anesthetic delivery around the nerve. Conclusions EI values differed between extra- and paraneural sites, and monitoring these values allowed prediction of the needle tip location with respect to the target nerve. Real-time EI measurement could improve the nerve block.

Diaphragmatic Hernia after Radiofrequency Ablation

Diaphragmatic hernia (DH) is a defect, which can be congenital or can develop later in life. Moreover, chromosomal and genetic abnormalities, environmental exposures, and nutritional deficiencies may be related to the development of congenital DH. In contrast, the risk factors of acquired DH include traumas, such as blunt injuries due to traffic accidents and surgical procedures. We report the case of a 71-year-old man admitted to our gastroenterology department for the treatment of esophageal varices. Four days after the endoscopic treatment, the patient vomited severely and reported severe right upper abdominal pain. He was diagnosed with DH, and surgical fixation was performed. The diaphragmatic injury lesion was located on the estimated needle track of percutaneous radiofrequency ablation, which was performed through the thoracic diaphragm with artificial pleural effusion for hepatocellular carcinoma.

Application of a treatment planning system-assisted large-aperture computed tomography simulator to percutaneous biopsy: initial experience of a radiation therapist

Objective To evaluate the application of treatment planning system (TPS)-assisted large-aperture computed tomography (CT) simulator to percutaneous biopsy. Methods This retrospective study enrolled patients that underwent TPS-assisted large-aperture CT simulator-guided percutaneous biopsy from November 2018 to December 2019. Retrospective analyses of puncture accuracy were compared using paired t-test and a Wilcoxon rank sum test. The risk factors for puncture accuracy and complications were identified. Results A total of 38 patients were included in this study. There were no significant differences between the planned and actual puncture depth and angle. Pulmonary puncture was significantly associated with the accuracy of the puncture angle. The diagnostic rate of malignancy was 76% (29 of 38), of which 20 of 25 patients were in the group initially diagnosed with unconfirmed lesions and nine of 13 patients were in the group of treated patients that needed additional pathological analyses. For patients that underwent a pulmonary biopsy, 12 had minor pneumothorax and three suffered needle track bleeding. No other complications were observed. Regression analyses indicated a significant correlation between puncture angle and the incidence of pneumothorax. Conclusion TPS-assisted large-aperture CT simulator may improve the percutaneous biopsy procedure by combining the advantages of radiotherapy specialties with computer targeting.

Assessment of needle tip geometry during infusions into a brain phantom gel

Convection-enhanced delivery (CED) is a promising method to deliver therapeutic drugs directly into the brain that has shown limited efficacy, mainly attributed to backflow, in which the infused drug flows back along the needle track rather than forward into tissue. This study evaluates the effect of sharp and blunt needle tips on backflow length under different flow rates via CED. Infusions were performed in a transparent 0.6% (w/v) brain phantom agarose hydrogel. Backflow length was significantly higher using sharp-tip needles for higher flow rates. No significant differences were observed between tip shapes for lower flow rates. In conclusion, sharp-tip needles present limitations for higher flow rates, which are needed to deliver more drug during shortest times.

Ultrasound-guided supraclavicular brachiocephalic vein catheterization in children: Syringe-free in-plane technique with micro-convex probe

Central venous catheterization of children is often a challenging procedure due to small anatomical structures. Ultrasound guidance has been shown to reduce complications and improve cannulation success as compared with the landmark-based technique. In-plane techniques allow for longitudinal visualization of the vessels and real-time visualization of needle track during its advancement. When in-plane and syringe-free techniques are combined, advancement of the guidewire can also be visualized. We aim to introduce our supraclavicular approach for brachiocephalic vein cannulation in pediatric patients. A syringe-free and in-plane technique is used to cannulate the patients. The subclavian, jugular, and the brachiocephalic veins were visualized by endocavity micro-convex ultrasound probe as a Y shape during the cannulation procedure. We present a case series of successful cannulation by using this technique.