title: A prospective comparative study of two indirect methods for confirming the localization of an epidural catheter for postoperative analgesia.
abstract: 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.
authors.affiliation: Departement d'Anesthesiologie Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Etienne
authors.initials: E
authors.lastname: de Medicis
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Tetrault
authors.forename: Rene
authors.initials: R
authors.lastname: Martin
authors.forename: Remi
authors.initials: R
authors.lastname: Robichaud
authors.forename: Lucie
authors.initials: L
authors.lastname: Laroche
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015360:Analgesia, Epidural / Q000379:methods*; D002404:Catheterization / Q000379:methods*; D004558:Electric Stimulation; D004824:Epidural Space; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000517:prevention & control*; D011446:Prospective Studies