title: Detection of subdural placement of epidural catheter using nerve stimulation.
abstract: OBJECTIVE
  To report the detection of a subdural catheter placement using nerve stimulation through an epidural catheter.
  
  
  METHODS
  An 85-yr-old gentleman was scheduled for radical cystectomy and creation of an ileal conduit. Combined general anesthesia and regional technqiue was selected. An epidural catheter (19 G Arrow Flextip Plus) was inserted prior to induction of general anesthesia. Intra-operatively, the patient received 5 mg morphine and 10 ml bupivacane 0.5% via the epidural catheter. The patient remained hemodynamically stable throughout the operation and did not require intravenous opioids. The patient was discharged to the ward with an order for epidural morphine for pain control. The next day, the patient remained comfortable. As an ongoing quality assessment to survey the success rate of epidural catheters at our institution, all patients are invited to have their catheter assessed using an electrical epidural stimulation test. Electrical stimulation (1-10 mA) with a segmental motor response (truncal or extremities movement) indicates that the catheter is in the epidural space. No motor response indicates that it is not. In this case, subdural catheter placement was suspected because a diffuse motor response including right anterior chest wall, back muscle, and bilateral lower extremities was observed using only 0.3 mA. Subdural catheter placement was subsequently confirmed by a radiograph showing a very thin film of dye spreading cephalad and caudad over many segments.
  
  
  CONCLUSIONS
  This new electrical test helps to detect subdural placement objectively.
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Alberta Hospitals, Walter Mackenzie Health Sciences Centre, Edmonton, Canada. btsui@ualberta.ca
authors.forename: B C
authors.initials: BC
authors.lastname: Tsui
authors.forename: S
authors.initials: S
authors.lastname: Gupta
authors.forename: D
authors.initials: D
authors.lastname: Emery
authors.forename: B
authors.initials: B
authors.lastname: Finucane
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000767:Anesthesia, Epidural / Q000009:adverse effects*; D002404:Catheterization / Q000009:adverse effects*; D004558:Electric Stimulation; D006801:Humans; D008297:Male; D013355:Subdural Space