Minimum current requirement for confirming the localization of an epiradicular catheter placement

Abstract

BackgroundBased on the necessity to confirm the epiradicular catheter misplacement, epiradicular threshold current for the confirmation of catheter tip localization is required.MethodsThirty-four adult patients with low extremity radiating pain were to receive epiradicular catheterization at the lumbosacral level. The epidural space was accessed percutaneously in cranial to caudal direction. A metal coil-reinforced epidural catheter was inserted and advanced caudolaterally toward the target neural foramen until the catheter tip was located below the bisection of pedicle. The electrical stimulation was performed after catheter placement in epidural and epiradicular space. Using the constant current nerve stimulator, the stimulating current was increased from 0 to 5 mA (pulse width of 0.3 ms; frequency of 2 Hz) until adequate motor contraction was evident. The threshold current for motor response with epidural space (EDmA) and epiradicular space (ERmA) placement were recorded upon electrical stimulation. In addition, the threshold charge for motor response with epidural (EDnC) and epiradicular (ERnC) placement were recorded.ResultsOf 34 catheters intentionally placed in the epiradicular space, ERmA was 0.53 ± 0.48 mA. The ERnC was significantly lower than EDnC (P < 0.05). The EDmA and ERmA were below 1 mA in 3 patients and above 1 mA in 4 patients, respectively.ConclusionsWe conclude that, threshold current for motor response seems to be lower for epiradicular compared with epidural placement, although we were not able to directly investigate the epidural threshold current. The threshold current of epiradicular space overlap that in the epidural space.

Efficacy of electrical stimulation on epidural anesthesia for cesarean section: a randomized controlled trial

“…Tsui et al [14] first described the use of electrical stimulation to confirm catheter placement in the epidural space. Subsequently, several researchers applied epidural stimulation for catheter placement [15][16][17]. Previous studies showed favorable results without side effects.…”

“…Their results were comparable to ours, but the mean stimulatory current threshold was different from Tsui's. Although the absolute value provided in Tsui's criteria was not applicable in different settings, at least it can signal catheter misplacement of intrathecal or epiradicular spaces when the values of the required current needed for electrical response were too low [16,17].…”

Electric stimulation-guided epidural analgesia for vaginal delivery: A randomized prospective study

“…Compared with the standard test dose, they reported a sensitivity of 100% and a specificity of 91.6% for epidural stimulation. Subsequently, several investigators have developed electric stimulation methods to confirm the correct placement of catheters in the epidural space, and have reported no side effects [16–18]. Previous studies have used an epidural catheter with a fixed electrode at the distal tip with the electric impulse conducted through normal saline within the lumen of the catheter [12,16].…”

Strategic placement of epidural catheter

“…In this issue of the Korean Journal of Anesthesiology, Jung et al [ 8 ] report on confirming the localization of an epiradicular catheter placement with different electrical pulse width. In the current study, instead of the threshold current, they compared the threshold charge.…”