Preliminary evaluation of a novel quantitative epidural access device (EpiduraFlow)

Accurate identification of the epidural space is critical for procedures such as labor analgesia, postoperative pain management, and epidural steroid injections. The current loss-of-resistance (LOR) technique depends on subtle tactile cues, which are highly subjective and prone to variability and complications. The objective was to develop and evaluate a prototype device (EpiduraFlow) that provides real-time quantitative feedback using pressure and flow metrics to enhance the accuracy and reliability of epidural space identification. A prototype system was designed incorporating a piezoelectric micropump, differential pressure sensors, and a microcontroller with LCD display. The device infused saline at a controlled rate through a Tuohy epidural needle, continuously recording flow and pressure. Testing was performed on a validated epidural simulation model at the UCSD Health SimCenter. Flow and pressure changes were analyzed during needle advancement across simulated tissue layers. Mean flow rate during advancement through simulated soft tissue and ligaments layers was 1.02 ± 0.84 µl s^-1, compared with 29.7 ± 5.3 µl s^-1upon entry into the simulated epidural space (p≪0.001). Pressure dropped correspondingly at the moment of entry, and changes were displayed in real time on the LCD. Calibration of sensors against a manometer demonstrated high linearity (R2>0.98). EpiduraFlow reliably identified transitions into the epidural space during simulated procedures. This proof-of-concept demonstrates the feasibility of objective, quantitative epidural localization and supports further development toward handheld, sterile-compatible designs and preclinical validation.