CONFIRMATION OF EPIDURAL CATHETER PLACEMENT USING NERVE-STIMULATION

Purpose: To examine the reliability of low current electrical epidural stimulation to confirm epidural catheter placement. Methods: Forty pa tients with epidural catheters (19G Arrow Flextip plus) already in pla ce for post-operative pain management were studied. An adapter (Arrow- Johans ECG Adapter) was attached to the connector of the epidural cath eter. The epidural catheter and adapter were filled with normal saline . The cathode lead of the nerve stimulator was attached to the metal h ub of the adapter. Catheter placement was judged to be correct or inco rrect, depending on the presence or absence of truncal or limb movemen t to 1 Hz stimulation (1-10 mA). A standard test dose (3 ml lidocaine 1.5% with 1:200,000 epinephrine) was then injected. The efficacy of th e epidural morphine was assessed independently. Results: The sensitivi ty and specificity of the test was 100% and 91.6% compared with the st andard test dose. The positive and negative predictive value was 96% a nd 100%. In predicting the clinical effect of epidural morphine, the s ensitivity and specificity was 96.1% and 76.99%. The positive and nega tive predictive value was 89% and 90%. The correlation of unilateral o r bilateral motor response from the test and sensory response from the lidocaine test with sensitivity and specificity was 91.6% and 53.0%. The predictive value for unilateral response from was 61% and for bila teral was 88%. Conclusion: This study establishes this test as a simpl e, objective and reliable technique for confirmation of epidural cathe ter placement.