What the phlebologist should know about local anesthetics

Endovenous thermal ablation in the treatment of large great saphenous veins of diameters > 12 mm: A systematic review meta-analysis and meta-regression

BACKGROUND

We sought to assess the safety and efficacy of endovenous thermal ablation (EVTA) in treating large great saphenous veins (GSV) > 12 mm in diameter.

METHODS

We performed a systematic review according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 for comparative and noncomparative studies depicting EVTA in the treatment of GSV > 12 mm. Primary endpoints included GSV occlusion, technical success, deep vein thrombosis (DVT), and endovenous heat-induced thrombosis (EHIT). We conducted a comparative analysis between GSV > 12 mm and < 12 mm and a meta-regression analysis for two sets of studies, one including the whole dataset, containing treatment arms of comparative studies with GSV < 12 mm and one exclusively for GSV > 12 mm.

RESULTS

Seven studies, including 2564 GSV, depicting radiofrequency (RFA) and endovenous laser ablation (EVLA) were included. GSV > 12 mm occlusion, technical success, DVT, and EHIT estimates were 95.9% (95% CI: 93.6-97.8), 99.9% (95% CI: 98.9-100.0), 0.04% (95% CI: 0.0-3.4), and 1.6% (95% CI: 0.3-3.5). Meta-regression revealed a negative association between GSV diameter and occlusion for both the whole dataset (p < 0.01) and the > 12 mm groups (p = 0.04), GSV diameter and technical success for both groups (p < 0.01), (p = 0.016), and GSV diameter and EHIT only for the whole dataset (p = 0.02). The comparative analysis between GSV < 12 mm and GSV > 12 mm displayed an occlusion estimate of OR 1.79 (95% CI: 1.25-2.56) favoring small GSV.

CONCLUSION

Whereas we have displayed excellent occlusion and technical success results for the EVTA of GSV > 12 mm, our analysis has illustrated the unfavorable impact of GSV diameter on occlusion, technical success, and EHIT outcomes regardless of the 12 mm threshold. Potential parameter or device adjustments in a diameter-oriented fashion could further enhance outcomes.

Saltatory conduction and intrinsic electrophysiological properties at the nodes of ranvier of Aα/β-afferent fibers and Aα-efferent fibers in rat sciatic nerves

Large-diameter myelinated fibers in sciatic nerves are composed of both Aα/β-afferent fibers and Aα-efferent fibers to convey sensory and motor impulses, respectively, via saltatory conduction for rapid leg responses. Saltatory conduction and electrophysiological properties at the nodes of Ranvier (NRs) of these sciatic nerve fibers have not been directly studied. We used ex vivo sciatic nerve preparations from rats and applied patch-clamp recordings at the NRs of both Aα/β-afferent fibers and Aα-efferent fibers in the sciatic nerves to characterize their saltatory conduction and intrinsic electrophysiological properties. The velocity and frequency of saltatory conduction in both types of fibers were similar. Resting membrane potentials (RMPs), input resistance, action potential (AP) threshold, and AP rheobase were also not significantly different at the NRs of the two types of fibers in the sciatic nerves. In comparison with Aα/β-afferent fibers, Aα-efferent fibers in the sciatic nerves show higher amplitude and broader width of APs at their NRs. At the NRs of both types of fibers, depolarizing voltages evoked transient inward currents followed by non-inactivating outward currents, and the inward currents and non-inactivating outward currents at the NRs were not significantly different between the two types of fibers. Using AP-clamp, inward currents during AP upstroke were found to be insignificant difference, but amplitudes of non-inactivating outward currents during AP repolarization were significantly lower at the NRs of Aα-efferent fibers than at the NRs of Aα/β-afferent fibers in the sciatic nerves. Collectively, saltatory conduction, ionic currents, and intrinsic electrophysiological properties at the NRs of Aα/β-afferent fibers and Aα-efferent fibers in the sciatic nerves are generally similar, but some differences were also observed.

Sudden quadriparesis after non-overdose local anesthesia

Background

A well-known anesthetic, lidocaine is the most widely used local anesthetic. Local anesthetic systemic toxicity (LAST) is a life-threatening event with common and prominent presentations of central nervous system (CNS) toxicity and cardiovascular toxicity. The most frequent and prominent early warning signs and symptoms of LAST are central nervous system symptoms. While rare, cases quadriparesis after the administration of lidocaine has been reported.

Case presentation

In this paper, we report a very rare case of quadriparesis after local anesthesia administration for vocal cord cyst-removal surgery, which dramatically improved after treatment. LAST can occur during various routes of lidocaine administration, such as local spray. A possible mechanism of our case could be the local diffusion of lidocaine to the spinal cord, which caused the symptoms to mimic anterior cord syndrome.

Conclusions

Our case presented a favorable outcome following the administration of intravenous lipid emulsion (ILE) for non-over dose local anesthetic drug induced spinal cord inhibition symptoms. These findings highlight the need for further research on the use of ILE to reverse LAST and other adverse effects of local anesthetics.

Update of the SFMV (French society of vascular medicine) guidelines on the conditions and safety measures necessary for thermal ablation of the saphenous veins and proposals for unresolved issues

Venous insufficiency is a very common disease affecting about 25% of the French population (if we combine all stages of its progression). It is a complex disease and its aetiology has not yet been fully elucidated. Some of its causes are well known, such as valvular dysfunction, vein wall defect, and the suctioning effect common to all varicose veins. These factors are generally associated and together lead to dysfunction of one or more of the saphenous veins. Saphenous vein dysfunction is revealed by ultrasound scan, a reflux lasting more than 0.5 seconds indicating venous incompetence. The potential consequences of saphenous vein dysfunction over time include: symptoms (heaviness, swellings, restlessness, cramps, itching of the lower limbs), acute complications (superficial venous thrombosis, varicose bleeding), chronic complications (changes in skin texture and colour, stasis dermatitis, eczema, vein atresia, leg ulcer), and appearance of unaesthetic varicose veins. It is not possible to repair an incompetent saphenous vein. The only therapeutic options at present are ultrasound-guided foam sclerotherapy, physical removal of the vein (saphenous stripping), or its thermal ablation (by laser or radiofrequency treatment), the latter strategy having now become the gold standard as recommended by international guidelines. Recommendations concerning thermal ablation of saphenous veins were published in 2014 by the Société française de médecine vasculaire. Our society has now decided to update these recommendations, taking this opportunity to discuss unresolved issues and issues not addressed in the original guidelines. Thermal ablation of an incompetent saphenous vein consists in destroying this by means of a heating element introduced via ultrasound-guided venous puncture. The heating element comprises either a laser fibre or a radiofrequency catheter. The practitioner must provide the patient with full information about the procedure and obtain his/her consent prior to its implementation. The checklist concerning the interventional procedure issued by the HAS should be validated for each patient (see the appended document).

Live-Cell Imaging of Physiologically Relevant Metal Ions Using Genetically Encoded FRET-Based Probes

Essential biochemical reactions and processes within living organisms are coupled to subcellular fluctuations of metal ions. Disturbances in cellular metal ion homeostasis are frequently associated with pathological alterations, including neurotoxicity causing neurodegeneration, as well as metabolic disorders or cancer. Considering these important aspects of the cellular metal ion homeostasis in health and disease, measurements of subcellular ion signals are of broad scientific interest. The investigation of the cellular ion homeostasis using classical biochemical methods is quite difficult, often even not feasible or requires large cell numbers. Here, we report of genetically encoded fluorescent probes that enable the visualization of metal ion dynamics within individual living cells and their organelles with high temporal and spatial resolution. Generally, these probes consist of specific ion binding domains fused to fluorescent protein(s), altering their fluorescent properties upon ion binding. This review focuses on the functionality and potential of these genetically encoded fluorescent tools which enable monitoring (sub)cellular concentrations of alkali metals such as K⁺, alkaline earth metals including Mg²⁺ and Ca²⁺, and transition metals including Cu⁺/Cu²⁺ and Zn²⁺. Moreover, we discuss possible approaches for the development and application of novel metal ion biosensors for Fe²⁺/Fe³⁺, Mn²⁺ and Na⁺.

Off-label use of tumescent local anaesthesia in endovascular and surgical techniques

Tumescent local anaesthesia (TLA)has increasingly established itself as the anaesthesia method for operations on varicose veins and has become the standard method in the case of endovascular techniques. However, Off-label use occurs due to the reduced concentration of the local anaesthetic, the incorporation of additives together with a high quantity of LA which exceed the manufacturer’s recommended maximum dosage. In spite of a lack of significant complications arising from the approved use of the TLA and unambiguous positive evaluations of this anaesthesia method by international medical professional associations, the operating phlebologist should inform the patient of this Offlabel use both in the case of operative procedures and endovascular techniques in order to avoid any legal problems.