Designing an Accurate and Customizable Epidural Anesthesia Haptic Simulator

Epidural anesthesia, despite being a relatively common medical procedure, remains quite demanding in terms of skills as it is mostly blind and thus heavily reliant on the haptic sensations. Although some training support solutions exist, anesthetists consider them mostly inefficient or impractical. A few attempts at creating a simulator for this particular procedure exist but each one lacks one of the important requirements of the procedure. This article introduces a haptic simulator featuring a more complete and realistic simulation of the procedure than we could observe in existing simulators. The simulator is composed of a generic electrical haptic interface coupled with a pneumatic cylinder.

I. Introduction

Epidural anesthesia is a commonly used medical gesture performed mainly during childbirth delivery, but it is very complex and hard to learn. This is mainly due to the fact that the procedure is mostly performed blind, relying solely on haptic cues and their interpretation by the anesthetist. To perform such a gesture, the practitioner has to insert a Tuohy needle between two vertebrae while injecting a fluid using an epidural syringe. The Tuohy needle has to cross several physiological layers, namely derma, supraspinous ligamentum, intraspinous ligamentum, and ligamentum flavum, to finally reach the epidural space. Throughout the insertion, the anesthetist experiences an increasing resistance felt both from the needle insertion and from the fluid injection. This resistance reaches its maximum when the needle tip crosses the ligamentum flavum, and suddenly plummets, creating what is commonly called the loss of resistance (LOR) principle. It is this phenomenon that allows physicists to know they reached the epidural space and this principle is specific to the epidural anesthesia procedure. Due to the relatively high forces exerted simultaneously on the needle and on the plunger of the syringe, the procedure is really demanding in term of precision as the epidural space is usually only about 4 mm wide, and about 6 mm deep.