Design and development of a visual syringe for epidural entry

Background: Inadvertent dural puncture is the most significant complication associated with epidural anaesthesia. These spinal taps can result in severe and prolonged headaches for the patient and, in rare cases, serious neurological complications. The current gold standard in epidural administration involves blindly passing a needle through the spinous processes of the vertebra until loss-of-resistance (LOR) is achieved on reaching the epidural space, resulting in a subtle and sudden pressure drop at the needle tip. The LOR technique relies exclusively on subjective haptic feedback on the syringe plunger and requires significant training until a reasonable proficiency is achieved. ProDural is a novel visual syringe for signalling needle entry into the epidural space. ProDural provides both visual and haptic feedback of probe entry into the epidural space by rapid and immediate collapse of an inflatable diaphragm whilst retaining haptic feedback. Methods: ProDural was designed based on criteria established through end user surveys, ethnographic feedback and existing technology assessment. The resulting solution was evaluated through physical bench-top experiments and analytical modelling prior to a pre-clinical cadaver trial. Conclusion: These initial trials indicate that ProDural may represent a promising approach to improving the accuracy of epidural needle placement and may reduce the steep learning curve associated with epidural administration.