Epidural space localization with CO2 and compliance

An increasing number of complications associated with standard loss of resistance (LOR) technique used during epidural injections shows a growing need for an improvement in correct identification of epidural space and minimization of possible risks. A prototype was constructed for delivery CO₂ gas into a standard epidural syringe and coupled with compliance sensing apparatus to evaluate effectiveness of localization of the epidural space in bovine spine sections. The safety of the prototype was tested under pressurized conditions. The accuracy of the compliance measurement was tested in muscle, cartilage, and adipose tissues. The CO₂ delivery system failure was estimated at approximately 50 psi. The prototype´s level of sensitivity correctly distinguished a change in compliance during the perforation of the adipose tissue in epidural space.