Response Patterns to the Electric Stimulation of Epidural Catheters in Pregnant Women: A Randomized Controlled Trial of Uniport Versus Multiport Catheters.
Abstract Number: F-71
Abstract Type: Original Research
Introduction: The trans-catheter electric stimulation test (TCEST) can confirm the placement of an epidural catheter within the epidural space (1,2). The most common response with a uniport catheter placed in the lumbar area is the unilateral contraction of the lower limbs (3), due to the positioning of the catheter on the left or the right of the epidural space. With a multiport catheter the current leaving through multiple orifices may be able to stimulate roots bilaterally at the same time and elicit a different motor response. We hypothesized that the incidence of bilateral muscle contraction would be higher with a multiport catheter as compared to the uniport catheter.
Methods: With institutional REB approval and patient consent, we conducted this randomized double-blind controlled study. We recruited laboring women requesting epidural analgesia. The epidural catheter was placed at L3/L4 as assessed by ultrasound. Patients were randomly allocated to receive either a 19 G uniport catheter or a 19 G multiport catheter (Arrow Flextip plus, Arrow International Inc., Reading, PA). The TCEST (frequency 2 Hz; pulse width 200 ms) was performed immediately after securing the catheter and at 5 minutes following a test dose with 3 ml of lidocaine 2%. Subsequently a loading dose of 10 ml of bupi 0.125% and fentanyl 50 mcg was administered, followed by a PCEA regimen with bupi 0.0625% with fentanyl 2 mcg/mL. Sensory level to ice was assessed at 20 min and at 2 h after the loading dose. Primary outcome was the motor response pattern to the TCEST.
Results: 63 women were approached, 53 recruited and 43 had data analyzed. Patient characteristics in both groups were similar. The incidence of unilateral response to the TCEST was 95.5 % and 95.2% in the uniport and multiport respectively (p= 0.99). The minimum current intensity (mean±SD) required to produce a motor response at baseline was 5.4±3.0 mA and 5.4±4.1 mA in the uniport and multiport groups respectively (p= 0.98). Sensory level to ice (median; IQR) at 20 min and 2 h were T8 (T6-T9) and T8 (T7-T9) in the uniport catheter and T8 (T8-T10) and T8 (T7-T10) in the multiport catheter (NS). The incidence of symmetrical block at 20 min was similar in the uniport and multiport groups (86.4% and 81% respectively, p=0.75); at 2 hours it was significantly lower in the multiport group (100% and 68.4% respectively (p=0.03). Analgesia was adequate in all patients.
Discussion: The results of this study show that the TCEST produced with a multiport catheter is similar to that produced with a uniport catheter. The unilateral contraction of the lower limbs is the most common response. Both catheters produce similarly effective analgesia. The different incidence of symmetrical block at 2 h may be a result of patient positioning and gravity effect during labor, which was not controlled in our study.
References: 1) Can J Anesth 1998;45:640-4; 2) Reg Anesth Pain Med 1999;24:17-23; 3) Can J Anesth 2013;60:393