Reduction of leakage from insertion site during continuous femoral nerve block with catheter-through-needle versus catheter-over-needle technique for postoperative analgesia after total knee arthroplasty: a randomized controlled trial

BACKGROUND

Continuous femoral nerve block (CFNB) is a common procedure used for postoperative analgesia in total knee arthroplasty. Continuous nerve block using a conventional needle (catheter-through-needle/CTN) is complicated by leakage of the anesthetic from the catheter insertion site. A different type of needle (catheter-over-needle/ CON) is now available, which is believed to reduce leakage as the diameter of the catheter is larger than that of the needle. The purpose of this study was to compare the incidence of leakage from the catheter insertion site during CFNB while using CTN and CON for postoperative analgesia after total knee arthroplasty (TKA).

METHODS

This prospective, randomized, single-blinded controlled study included 60 patients who were scheduled for TKA at our facility between May 2016 and November 2017. Patients were randomly allocated to the CTN or CON groups. All patients in both groups received CFNB and sciatic nerve block for postoperative analgesia. The administration of 0.16% levobupivacaine mixed with 6 mg of indigo carmine (a dye added to easily identify leakage) was started at 6 ml/h at the end of surgery. The primary outcome was the incidence of leakage from the catheter insertion site. We further investigated the degree of leakage, the incidence of catheter migration, pain scores using the numerical rating scale at 48 h postoperatively, and the number of days until the operated knee could be flexed 120 degrees postoperatively in both groups.

RESULTS

The CON group had a significantly lower incidence and degree of leakage from the catheter insertion site. There were no significant differences in other measurement outcomes.

CONCLUSIONS

Use of CON reduces the incidence of leakage from the catheter insertion site during CFNB in the use of postoperative analgesia for total knee arthroplasty. Future research is needed to determine additional benefits of using CON related to decreased leakage.

TRIAL REGISTRATION

The study was registered in the University Hospital Medical Information Network (UMIN) Clinical Trials Registry ( UMIN000021537 ), prospectively registered on 18 March 2016.

Recognition and differentiation of dural puncture click sensation: A subjective and objective prospective study of dural puncture forces using fine-gauge spinal needles

BACKGROUND

We hypothesized that the click perceived when puncturing the dura-arachnoid with fine-gauge spinal needles can be subjectively identified, and investigated whether it may be distinguishable among different needle types.

METHODS

Subjective and objective evaluations were performed. First, physicians punctured the polyamide film or porcine dura mater (n = 70 and n = 20, respectively) with seven types of spinal needles and numerically evaluated the perceived click sensations. Using an 11-point numerical rating scale (from "0" for "no click sensation" to "10" for "the strongest click perceived") data, subjective differentiation among needle types was assessed. Second, in the objective part of the study, total forces elicited by polyamide film or porcine dura mater punctures with each needle were measured using a biomechanical testing device, and load-displacement curves evaluated. Third, the results of subjective and objective evaluations were compared.

RESULTS

All participants recognized the click and could discriminate among needles of different tip shape. The load-displacement curves for polyamide film and porcine dura mater were similar and needle-specific. The subjective numerical rating scale values corresponded well with the objectively measured changes in total forces (R2 = 0.862 and R2 = 0.881 for polyamide film and porcine dura mater, respectively), indicating that an increase in the largest drop in total force value of 0.30 N or 0.21 N would produce an increase of numerical rating scale value of 1 for polyamide film and porcine dura mater, respectively.

CONCLUSIONS

We provide an objective proof of the click sensation felt upon dural puncture using different fine-gauge spinal needles. Click recognition could be used as an additional indicator of successful spinal puncture.

The change of antizyme inhibitor expression and its possible role during mammalian cell cycle

Antizyme inhibitor (AIn), a homolog of ODC, binds to antizyme and inactivates it. We report here that AIn increased at the G1 phase of the cell cycle, preceding the peak of ODC activity in HTC cells in culture. During interphase AIn was present mainly in the cytoplasm and turned over rapidly with the half-life of 10 to 20 min, while antizyme was localized in the nucleus. The level of AIn increased again at the G2/M phase along with ODC, and the rate of turn-over of AIn in mitotic cells decreased with the half-life of approximately 40 min. AIn was colocalized with antizyme at centrosomes during the period from prophase through late anaphase and at the midzone/midbody during telophase. Thereafter, AIn and antizyme were separated and present at different regions on the midbody at late telophase. AIn disappeared at late cytokinesis, whereas antizyme remained at the cytokinesis remnant. Reduction of AIn by RNA interference caused the increase in the number of binucleated cells in HTC cells in culture. These findings suggested that AIn contributed to a rapid increase in ODC at the G1 phase and also played a role in facilitating cells to complete mitosis during the cell cycle.

Regulation of ornithine decarboxylase by antizymes and antizyme inhibitor in zebrafish (Danio rerio)

Mammalian polyamine synthesis is regulated by a unique feedback mechanism. When cellular polyamine levels increase, antizyme, an ornithine decarboxylase (ODC) inhibitory protein, is induced by polyamine-dependent translational frameshifting. Antizyme not only inhibits ODC, a key enzyme in polyamine synthesis, it also targets the enzyme degradation by the 26S proteasome. Furthermore, it suppresses cellular uptake of polyamines. Previously, we isolated two zebrafish antizymes with different expressions and activities. This suggested that a common feedback mechanism of polyamine metabolism might operate in mammals and zebrafish (Danio rerio). In the present study, cDNAs of zebrafish ODC and antizyme inhibitor, another regulatory protein that inhibits antizyme action, were cloned. The presence of ODC and antizyme inhibitor mRNAs was confirmed by Northern blotting in embryos and adult fish, as well as in a zebrafish-derived cell line (BRF41). The activity of the ODC cDNA expression product was inhibited by short and long zebrafish antizymes, and recombinant zebrafish antizyme inhibitor reversed this inhibition. In the BRF41 cells, the ODC half-life was considerably longer than that of mammalian ODC but shorter than that of Schizosaccharomyces pombe. Spermidine elicited a rapid decay of ODC activity and ODC protein in a protein synthesis-dependent manner.

Two zebrafish (Danio rerio) antizymes with different expression and activities

Cellular polyamines are regulated by a unique feedback mechanism involving ornithine decarboxylase (ODC) antizyme. The synthesis of mammalian antizyme requires a programmed translational frameshift event induced by polyamines. Antizyme represses ODC, a key enzyme for polyamine synthesis, through accelerating enzyme degradation by the 26 S proteasome. Antizyme also inhibits the cellular uptake of polyamines. In the present study we isolated two distinct zebrafish (Danio rerio) antizyme cDNA clones (AZS and AZL) from an embryonic library. Their sequences revealed that both clones required translational frameshifting for expression. Taking account of +1 frameshifting, AZS and AZL products were 214 and 218 residues long respectively and shared 51.8% amino acid identity. In rabbit reticulocyte lysates, both mRNA species were translated through spermidine-induced frameshifting. The presence of the two antizyme mRNA species in embryos, adult fish and a cultured cell line was confirmed by Northern blot analysis. The ratio of AZS mRNA to AZL mRNA in the adult fish was 1.8-fold higher than in the embryos. Whole-mount hybridization in situ demonstrated that both mRNA species are expressed in every tissue in embryo, but predominantly in the central nervous system and the eyes. Bacterial expression products of both cDNA species inhibited ODC activity, but only the AZS product accelerated ODC degradation in vitro. These results show that both zebrafish antizymes are induced by polyamines but their mRNA species are expressed differently during development. The difference in activities on ODC degradation suggests their functional divergence.