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.

The effect of different dietary zinc sources on mineral deposition and antioxidant indices in rabbit tissues

<p>The purpose of this study was to compare the effect of dietary zinc from inorganic and organic sources on the concentration of Zn, Cu, Mn and Fe in plasma, tissues and faeces of rabbits. Simultaneously, the activities of total superoxide dismutase (SOD), specific Cu/Zn SOD, glutathione peroxidase (GPx), lipid peroxidation and total antioxidant capacity (TAC) in liver and kidney were also determined. Ninety-six 49-day-old broiler rabbits were allocated to 4 dietary treatments, each replicated 6 times with 4 animals per replicate. For the subsequent 6 wk, the rabbits were fed an identical basal diet (BD) supplemented with an equivalent dose of Zn (100 mg/kg) from different sources. Group 1 (control) received the unsupplemented BD, while the BD for groups 2, 3 and 4 was supplemented with Zn from Zn sulphate, Zn chelate of glycine hydrate (Zn-Gly) and Zn chelate of protein hydrolysate (Zn-Pro), respectively. The intake of dietary Zn sulphate resulted in an increase in Zn plasma concentration (1.85 vs. 1.48 mg/L; <em>P</em>&lt;0.05) compared to the control group. Feeding the diets enriched with Zn increased the deposition of Zn in the liver (<em>P</em>&lt;0.05), irrespective of the Zn source. The addition of Zn-Pro resulted in significantly higher Cu uptake in liver (<em>P</em>&lt;0.05) than in the control and Zn sulphate group (56.0 vs. 35.0 and 36.7 mg/kg dry matter (DM), respectively). Neither Mn nor Fe concentration in plasma and tissues were affected by dietary Zn supplementation, with the exception of Fe deposition in muscle, which was significantly decreased (<em>P</em>&lt;0.05) in rabbits supplemented with inorganic Zn sulphate compared to control and Zn-Gly group (9.8 vs. 13.3 and 12.2 mg/kg DM, respectively). Intake of organic Zn-Gly significantly increased the activities of total SOD (43.9 vs. 35.9 U/mg protein; <em>P</em>&lt;0.05) and Cu/Zn SOD (31.1 vs. 23.8 U/mg protein; <em>P</em>&lt;0.01) as well as TAC (37.8 vs. 31.2 μmol/g protein; <em>P</em>&lt;0.05) in the kidney when compared to that of the control group. The presented results did not indicate any differences between dietary Zn sources in Zn deposition and measured antioxidant indices in rabbit tissues. Higher dietary Zn intake did not cause any interactions with respect to Mn, Cu and Fe deposition in liver and kidney tissues, but did increase the faecal mineral concentrations. Dietary organic Zn-Gly improved the antioxidant status in rabbit kidney.</p>