Efficacy of the Epidural Positioning Device® in optimizing the acoustic target window for neuraxial needle placement in term pregnancy.

Background: Neuraxial anesthesia can be challenging in obstetric patients due to the gravid uterus interfering with patient positioning. Ultrasound is commonly used in obstetric anesthesia to facilitate neuraxial needle placement. Some positioning maneuvers facilitate the ultrasound visualization of structures and the placement of neuraxial needles, but the Epidural Positioning Device (EPD) has yet to be evaluated.

Objectives: Our goal was to evaluate whether the use of the EPD increased the acoustic target window in the lumbar area of pregnant patients. We hypothesized that the application of the EPD would increase the measured lengths of the paravertebral longitudinal ligament (PLL), the interlaminar distance (ILD) and the ligamentum flavum (LF).

Methods: Lumbar ultrasonography was performed on 29 pregnant women having an elective cesarean delivery. Two anesthesiologists independently scanned the L3-4 right paramedian space, using a curvilinear ultrasound transducer, in two positions for each patient: traditional sitting with lumbar flexion and sitting with use of the EPD for lumbar flexion. The PLL, ILD and LF lengths were measured using the ultrasound caliper software and recorded, with the anesthesiologists blinded to the results. Patients were asked to rate their comfort in both positions.

Results: There were no significant differences between the measured lengths of the PLL, ILD and LF in the two positions. Patient comfort was significantly higher with use of the EPD (OR 10, 95% CI 2.4 to 88).

Conclusion: Although the application of an EPD did not improve the paramedian acoustic target area in term parturients, greater patient comfort might facilitate needle placement.