Lignocaine Permeability through the Paraneural Sheath andHuman Sciatic Nerve A Study on In Vitro Biological Membraneand Nerve Model

Abstract

Abstract newlineBackground: Even after the introduction of ultrasound in regional anaesthesia significantly higher amount of local anaesthetics are being injected perineurally to produce the desired clinical effect during peripheral nerve blockade compared to the spinal anaesthesia. Furthermore, clinical outcomes vary markedly with different injection sites even within the same nerve block. The increased local anesthetic requirement and high variability observed across different injection sites were attributed to the resistance offered by the multiple layers of perineural connective tissue to the LA diffusion. Preclinical research on rat sciatic nerve concluded that the perineurium is the rate limiting layer for LA diffusion. newlineObjectives: This study aimed to quantify the permeability of lignocaine through the paraneural sheath (PNS) of the human sciatic nerve and to evaluate lignocaine uptake by the human sciatic nerve without the PNS. newlineMethods: The study was conducted in three sequential stages: newline1. Design, Development, and Validation of Shan-DDC: Given the lack of a suitable device for our experimental objectives, a novel Static Horizontally Aligned Drug Diffusion Cell (Shan-DDC) was designed, developed and validated to suit our experimental requirements. newline2. Permeability Measurement of the Paraneural Sheath (PNS): After obtaining Institutional Review Committee (IRC) and Ethical Committee approval, 26 sciatic nerves were harvested from 13 deceased donors within 24 hours post-mortem during autopsy. The PNS was carefully separated, mounted onto the Shan-DDC, and lignocaine permeability was systematically quantified. newline3. Lignocaine Uptake by the Human Sciatic Nerve: Following PNS removal, sciatic nerve segments were incubated in phosphate-buffered saline (PBS) containing 1% newlinelignocaine. Samples were collected at predetermined intervals to measure lignocaine uptake within the nerve tissue using mass spectrometry. newlineDesign, Development and validation of Shan-DDC. newlineThe diffusion cell consists of a donor and a recipient chamber engr