A prospective comparative study of two indirect methods for confirming the localization of an epidural catheter for postoperative analgesia

Document Type


Peer Reviewed


Publication Date


NLM Title Abbreviation

Anesth Analg

Journal/Book/Conference Title

Anesthesia and Analgesia

PubMed ID


DOI of Published Version


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We prospectively evaluated, in randomized order, 2 indirect methods of confirming the localization of an epidural catheter for postoperative analgesia in 218 surgical patients: epidural stimulation test (EST) and epidural pressure waveform analysis (EPWA). The epidural space was localized by using a loss of resistance technique. All catheters were inserted 5 cm into the epidural space and primed with 5 mL of 0.9% normal saline. There were no differences between the methods: the positive predictive value and specificity were high (100% in both groups), but the sensitivity was moderate (80% for EST and 81% for EPWA) and the negative predictive value was low (16% for EST and 17% for EPWA). Combining both methods yielded better sensitivity (97%) and negative predictive value (57%) (P < 0.001). The sensitivity of EST was increased to 87% (P < 0.05) if sensory response was included as well as motor response for stimulation less than 10 mA. We suggest the inclusion of sensory response in the appropriate dermatome at a current <10 mA as a criterion for adequate epidural catheter localization for EST testing. EPWA sensitivity was significantly better with older patients: 94% for patients older than 80 yr compared with 63% for patients younger than 40, 73% for patients 40 to 60, and 85% for patients aged 60 to 80 yr (P = 0.03). We conclude that the two tests are comparable for confirming catheter placement.


Adult, Aged, Aged, 80 and over, Analgesia, Epidural/methods, Catheterization/methods, Electric Stimulation, Epidural Space, Female, Humans, Male, Middle Aged, Pain, Postoperative/prevention & control, Prospective Studies

Published Article/Book Citation

Anesthesia and Analgesia, 101:6 (2005) pp.1830-1833. DOI:10.1213/01.ANE.0000184130.73634.BE.

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