Experimental validation of the CompuFlo® epidural controlled system to identify the epidural space and its clinical use in difficult obstetric cases

Differentiating False Loss of Resistance from True Loss of Resistance While Performing the Epidural Block with the CompuFlo® Epidural Instrument

“…In a chronic pain management study, an equivalent success rate of 100%, demonstrated by the correct spread of dye during fluoroscopy, was observed in a comparison between the standard LOR epidural technique and CompuFlo® [10]. Other studies in obstetric setting have confirmed the complete analgesic success after the use of CompuFlo® to detect the epidural space [6, 7]. In these latter studies was also hypothesized that this instrument was very useful in helping the anesthesiologist to correctly differentiate the false loss of resistance from the true loss of resistance encountered during the epidural needle advancement during the epidural procedure with the LORT.…”

“…During advancement of the Tuohy needle, pressures were displayed and recorded continuously and the instrument produced an audible tone whose pitch was in accordance with the height of the pressure. According to previous studies [6, 7], a true LOR, indicating the epidural needle has reached the epidural space, was defined as the following pattern: an increase in pressure (accompanied by an increase in the pitch of the audible tone) followed by a sudden and sustained drop in pressure for more than 5 seconds (typically greater than 50% of the maximum pressure) accompanied by a sudden decrease in the pitch of the audible tone, resulting in the formation of a “low and stable pressure plateau.” A false LOR was defined as an increase in pressure followed by a drop in pressure (typically less than 50% of the maximum pressure) that is either not sustained or inconclusive of representing a “low and stable pressure plateau.” If the pressure rapidly increased after a drop in pressure, this was identified as a false loss of resistance, and the operator was elected to continue to advance the needle.…”

“…An audible and visual graphic of exit pressure is provided to focus on the procedure. This instrument has been investigated and validated for epidural use [6, 7].…”

“…CompuFlo® has also been reported to be able to differentiate the false loss of resistance due to the location of the epidural needle within the epidural region tissues and the true loss of resistance due to the penetration of the needle into the epidural space [6, 7] (Figure 1), but the sensitivity of this feature is unknown.…”

Alternate method of loss of resistance test using 3-way stopcock and two syringes

“…This pressure is higher than the pressures produced by Epimatic® and Episure Autodetect® syringes[6] but according to literature this pressure can be safely used for epidural space identification with LORT. [7]…”