ENGS 89/90 Reports

Degree Program


Year of Graduation


Project Advisor

Ryan J. Halter

Document Type


Publication Date

Winter 3-1-2019


Executive Summary - Group 8: Design of Sensor Enhanced Epidural Access Device

Epidural anesthesia is a common technique used for pain control in a variety of clinical procedures. It is most commonly used for labor pain but is also utilized for other procedures that require patient consciousness. For sufficient pain relief to be achieved, an epidural catheter must be inserted into the epidural space so that anesthetic solution can be continuously delivered to a targeted area. Currently, proper placement of the catheter is achieved by feel, using the loss of resistance (LOR) technique. This technique is subject to clinician experience and the ability todetect small changes in resistance, which vary with each patient’s bodily composition. Thediversity in patient spinal anatomy is further complicated by an inability to visually confirm needle placement without additional imaging such as fluoroscopy. Not only is employing an imaging method an added expense, but, for example, fluoroscopy cannot be used to help insert epidural catheters in laboring women. These variables make it difficult to establish a standardized sensation for the LOR technique, ultimately contributing to epidural catheter insertion failure rates that have significant room for improvement.

Rockport Medical Technologies developed a needle guidance technology that has the ability to significantly improve the first-time success rate of epidural catheter insertions by using pressure waveform analysis to assess needle positioning. This device attaches to the proximal end (relative to the patient) of the syringe. The clinician uses the standard LOR technique, but has the useful addition of visual confirmation of needle placement, which is confirmed by anLED light. The device’s current design imposes significant changes to the surgeon’s standardworkflow. Furthermore, it has human factors limitations that make it undesirable. This projectaims to optimize the design, grip, and physical dimensions of RMT’s device to create anergonomically viable innovation while maintaining a sterile field.

A user survey sent to clinicians at DHMC in the Fall helped the team narrow down preliminary designs to three options during the PDR. These designs included similarities to the current state of the art to give surgeons familiar points of reference on the new device. The group collectively observed approximately 20 epidural catheter placement procedures at DHMC and collected feedback from 14 anesthesiologists. The team built an in-house test bench made of silicone rubber and ballistics gel to serve as a platform to test the later-generation prototypes and finalize the form factor of the final design. Our final design was preferred second only to theteam’s optimized model, which is too small to house the current dimensions and configuration ofRMT’s electronics package; we have presented this model as a recommendation for future work.With our design requirements, polymers are the optimal choice for both the shell and needle cartridge. We present our sponsor with three options for manufacturing: injection molding, molding with urethane resin, and low-pressure overmolding.

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