Jae Chol Shim

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

Background Based on the necessity to confirm the epiradicular catheter misplacement, epiradicular threshold current for the confirmation of catheter tip localization is required. Methods Thirty-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. Results Of 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. Conclusions We 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.

Fluoroscopic analysis of lumbar epidural contrast spread after retrograde interlaminar ventral epidural injection (RIVEI).

Background Retrograde interlaminar ventral epidural injection (RIVEI) may hypothetically be more effective if the catheter is placed at the ventrocaudal aspect of the exiting nerve. We tested that hypothesis by measuring ventral and dorsal epidural contrast flow during RIVEI. Methods To perform RIVEI, a 17 G Tuohy needle was inserted to access the epidural space. A 19 G epidural catheter was inserted and advanced through the needle, passing in a caudal direction to the lower aspect of the contralateral pedicle. Fluoroscopic images were recorded at 1.5 ml increments of contrast. Based on the images of contrast dispersal, the extent of contrast spreading was assessed in 82 patients. Results All 82 patients (100%) injected with 3.0 ml contrast medium demonstrated ventral epidural spreading. Mean spreading level from the catheter tip was 2.21 ± 0.93 with 3.0 ml of contrast. Spreading to the superior aspect of the supra-adjacent intervertebral disc was observed in 67/82 (81.7%) of RIVEIs with 3.0 ml of contrast injected into the ventral epidural space. We found that 3.0 ml of contrast reached the inferior aspect of the infra-adjacent intervertebral disc in 95.1% (78/82) of RIVEIs performed. Conclusions Our findings imply that a one-level RIVEI may be sufficient in situations where a two-level injection would currently be used.

Intraoperative Pulmonary Embolism: A case report

A 62 year old female patient was transferred to the operating room for open reduction and internal fixation of the left femur fracture under general anesthesia. At 15min. after femur tourniquet application, there were suddenly decreased oxygen saturation, end-tidal CO2 concentration and blood pressure. We suspected a pulmonary embolism, and attempted vigorous emergency treatment and intensive care including ventilator care, vasopressor drug use, pulmonary artery pressure monitoring. At the 5th day after intensive care unit, she was transferred to general ward and she discharged without any sequelae after 17th day postoperatively. (Korean J Anesthesiol 1997; 33: 187∼191)