Does epinephrine improve the diagnostic accuracy of aspiration during labor epidural analgesia?

Aspiration reliably detects almost all IV multiorifice epidural catheters. Although a supplemental epinephrine 15-mu g test dose may detect the rare T V catheter that does not yield blood on aspiration, false-positive epinephr ine responses may cause some women to unnecessarily undergo repeat epidural catheter insertion. We evaluated 532 consecutive eligible patients request ing neuraxial labor analgesia. Patients were excluded if they had a contrai ndication to epinephrine or if they received intrathecal sufentanil/bupivac aine. Multiorifice catheters were inserted 4-6 cm into the epidural space a s part of an epidural (n = 305) or combined spinal-epidural (n = 270) techn ique. We used aspiration, a lidocaine/epinephrine test dose, and bolus inje ction or infusion of dilute bupivacaine/sufentanil solutions to systematica lly determine TV, intrathecal, or epidural catheter location. Aspiration al one detected 47 of 48 intravascular catheters. There were 10 positive epine phrine responses: 2 were true positives, 7 were falsely positive (subsequen t local anesthetic injection/infusion produced bilateral sensory change and analgesia), and 1 catheter was removed without further testing. Aspiration detected almost all intravascular catheters. Although the epinephrine test dose did detect one catheter that proved to be in a blood vessel, 87.5% of positive responses occurred in women without intravascular catheters. Impl ications: Epidural catheters may enter a blood vessel. Many clinicians use epinephrine to detect these catheters. Because aspiration alone detects alm ost all TV multiorifice catheters in laboring women, a subsequent epinephri ne test dose may be unnecessary.