///2010 Abstract Details
2010 Abstract Details2018-05-01T17:52:49+00:00

The epidural electric stimulation test does not predict labor epidural analgesia patterns

Abstract Number: 19
Abstract Type: Original Research

Aleksandra Dlacic MD1 ; Louis Furtado BA2; Clarita Margarido MD, PhD3; Mrinalini Balki MD4; Jose C.A. Carvalho MD, PhD5

Introduction: The epidural electrical stimulation test (EEST) is an excellent method to detect the presence of epidural catheter in the epidural space. This study was conducted to determine if EEST can be used to predict abnormal patterns of epidural analgesia, and consumption of epidural drugs in laboring women.

Methods: REB approval and written informed consent were obtained. We included women with cervical dilatation 0-5cm and pain VAS >6, requesting labor epidural. The epidural space was identified using LOR to air or saline, and a 19G catheter was advanced 5 cm into the epidural space. Current output was increased from 0.1 mA until motor activity was detected. EEST was performed at baseline, and repeated 5 min following a test dose of 3ml of 2% lidocaine. The loading dose was 10ml of 0.125% bupivacaine+50g fentanyl, followed by PCEA with 0.0625% bupivacaine+2g/ml fentanyl. In case of inadequate analgesia at 20 min, 10ml of bupivacaine 0.25% was given. In case of further inadequate analgesia during the study, 10 ml of 0.125%, followed by 10 ml of 0.25% was given. The study was terminated 2 hours after the initiation of epidural infusion. Primary outcome: total bupivacaine consumption. Secondary outcomes: incidence of asymmetric and inadequate blocks, minimum current to elicit motor response before and after the test dose, and muscle contraction patterns.

Results: 107 women were recruited. The mean electric current required to elicit muscle response at baseline was 4.4mA (range1-10mA), and the mean delta current (post test dose-baseline) was 1.5mA (range 0-8mA). There was no correlation between the baseline or the delta current and bupivacaine consumption (correlation coefficients -.072 and 0.066 respectively). The incidence of both asymmetric and inadequate blocks was 18%. There was no difference in the baseline and delta currents, or bupivacaine consumption between groups with symmetric and asymmetric blocks, and between groups with adequate and inadequate blocks. The pattern of muscle contraction was: right thigh 15%, left thigh 10%, right leg 27%, left leg 32%, bilateral thigh 0%, bilateral leg 4% and 4% other.

Conclusions: The EEST shows a wide range of electrical current requirements, and elicits a variety of muscle contraction patterns. The results of the EEST cannot be used to predict local anesthetic consumption, and asymmetric or inadequate blocks during labor epidural analgesia.

References: Can J Anesth 1998; 45:640-4



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