The use of a sound-enabled device to measure pressure during insertion of an epidural catheter in women in labour

Abstract

SummaryThe insertion of an epidural catheter for labour analgesia may be challenging. This observational study compared pressures during insertion of an epidural catheter in pregnant (n = 35) and non-pregnant (n = 10) women, using an acoustic device for locating the epidural space that also records and stores pressure data during the procedure. In both groups, we compared the maximum pressure just before loss of resistance, the pressure in the epidural space and the pressure in the inserted epidural catheter. Maximum pressure just before loss of resistance in the pregnant women was significantly lower compared with the non-pregnant women. Pressures in the epidural space and with the disposable tubing connected to the inserted epidural catheter were greater in pregnant women than in non-pregnant women. The results support the hypothesis that physiological changes in the third trimester of pregnancy are the reason why epidural catheters are more difficult to insert in women in labour.

A New Pressure Guided Management Tool for Epidural Space Detection: Feasibility Assessment on a Simulator

“…Considering the force uniformly exerted on the either the sensor active area or the syringe plunger, the pressure exerted on the sensing area of the sensor can be considered as the ratio between the force F and the area of the plunger (i.e., ≈314 mm 2 ). Therefore, the measurement range of the sensor (i.e., 0.2–20 N) corresponds to a pressure range of (0.64–64 kPa), which allows covering all the values of interest considering the specific application (the pressure exerted during the entrance to the epidural space is about 8 kPa, as reported in ).…”

“…The resistance of the Wheatstone bridge ( R 0 ) influences the performance of the system: an increment of R 0 allows increasing the V WB changes with R x at low P (sensitivity increase); however, the saturation of V WB happens at lower P (the measuring range is lower). The choice of R 0 = 100 kΩ is a good trade‐off for the application of interest: the output saturated at ∼20 kPa (corresponds to ∼6.2 N) that is lower than the pressure exerted during passage through the ligamentum flavum (about 35 kPa) so in this phase the system is under saturation condition, but it is higher than the pressure exerted when the epidural space is reached (<10 kPa) Therefore, the LOR must be detected as the passage from the output at the saturation stage to a voltage decrease.…”

“…We set these two values at 2 s and 10 kPa considering a potential clinical scenario. Indeed, the time interval of 2 s may allow avoiding false positives caused by noise and potential LOR caused by movements of the practitioner; the threshold of 10 kPa may avoid false positive because it is lower than the pressure needed to penetrate the biological tissue during epidural puncture, and may allow detecting the entrance into epidural space because the pressure is lower than 10 kPa, as reported in . Finally, the ESMT stores the pressure data that can be used to evaluate the improvement of trainees so as to quantify the effectiveness of the insertion.…”

“…Recent studies have shown the introduction of new techniques aiming to have an objective detection of the LOR, and, in many cases, these investigations have led to commercial devices .…”

Cervical epidural puncture guided by fluoroscopy in comparison to acoustic signals: Clinical results

“…It has shown reliable results to detect epidural space in both lumbar and thoracic area. [5678] It provides an objective end point using both visual and auditory senses. Furthermore, it allows the usage of both hands for needle insertion.…”