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

Abstract

Background. The occurrence of false losses of resistance may be one of the reasons for inadequate or failed epidural block. A CompuFlo® epidural instrument has been introduced to measure the pressure of human tissues in real time at the orifice of a needle and has been used as a tool to identify the epidural space. The aim of this study was to investigate the sensitivity and the specificity of the ability of CompuFlo® to differentiate the false loss of resistance from the true loss of resistance encountered during the epidural space identification procedure. Method. We performed epidural block with the CompuFlo® epidural instrument in 120 healthy women who requested labor epidural analgesia. The epidural needle was considered to have reached the epidural space when an increase in pressure (accompanied by an increase in the pitch of the audible tone) was followed by a sudden and sustained drop in pressure for more than 5 seconds accompanied by a sudden decrease in the pitch of the audible tone, resulting in the formation of a low and stable pressure plateau. We evaluate the sensitivity, specificity, and positive and negative predictive values of the ability of CompuFlo® recordings to correctly identify the true LOR from the false LOR. Results. The drop in pressure associated with the epidural space identification was significantly greater than that recorded after the false loss of resistance (73% vs 33%) (P=0.000001). The sensitivity was 0.83, and the AUC was 0.82. Discussion. We have confirmed the ability of CompuFlo® to differentiate the false loss of resistance from the true loss of resistance and established its specificity and sensitivity. Conclusion. An easier identification of dubious losses of resistance during the epidural procedure is essential to reduce the number of epidural attempts and/or needle reinsertions with the potential of a reduced risk of accidental dural puncture especially in difficult cases or when the procedure is performed by trainees.

Epidural Space Identification Using Continuous Real-Time Pressure Sensing Technology (CompuFlo<sup>®</sup>): A Report of 600 Consecutive Cases

“…Previous studies have reported the ability and reliability of the CompuFlo ® instrument to detect the epidural space and thereafter to obtain the analgesic success of the epidural block [1] [2] [3]. This instrument is also reported to be very useful in helping the anesthesiologist correctly differentiate the false from true losses of resistances encountered as an epidural needle advances during the epidural procedure [5] and in being used as a teaching simulation tool [6]. Accidental dural puncture 0 0% Figure 1.…”

Epidural: Loss of Resistance

“…In case of false LOR any one of the above is not achieved. If the pressure increases after drop in pressure it is a false LOR [39].…”

To the editor: comments on the paper: pressure monitoring devices may undetect epidural space: a report on the use of Compuflo® system for epidural injection

“…In their letter the Authors provided the following statement: “ Pressure monitoring devices have already been reported to give false negatives in detecting the epidural space by Carassiti et al [ 1 ]”, giving the reader the impression that other researchers have also reported misdetections of the epidural space. However, Vaira’s paper [ 4 ] did not studied “false-negatives” but demonstrated that the drop in pressure associated with the epidural space identification (true loss of resistance) was significantly greater than that recorded after the false loss of resistance. In addition, the false negatives reported by Vaira et.…”