Background and Objectives: Epidural analgesia is an established method for pain management. The failure rate is 8% to 12% due to technical difficulties (catheter dislocation and/or disconnection; partial or total catheter occlusion) and management. The mechanical properties of the catheters, like tensile strength and flow rate, may also be affected by the analgesic solution and/or the tissue environment.

Methods: We investigated the tensile strength and perfusion pressure of new (n = 20), perioperatively (n = 30), and postoperatively (n = 73) used epidural catheters (20-gauge, polyamide, closed tip, 3 side holes; Perifix [B. Braun]). To prevent dislocation, epidural catheters were taped (n = 5) or fixed by suture (n = 68) to the skin. After removal, mechanical properties were assessed by a tensile-testing machine (INSTRON 4500), and perfusion pressure was measured at flow rates of 10, 20, and 40 mL/h.

Results: All catheters demonstrated a 2-step force transmission. Initially, a minimal increase of length could be observed at 15 N followed by an elongation of several cm at additional forces (7 N). Breakage occurred in the control group at 23.5 ± 1.5 N compared with 22.4 ± 1.6 N in perioperative and 22.4 ± 1.7 N in postoperative catheters (P < 0.05). Duration of catheter use had no effect on tensile strength, whereas perfusion pressure at clinically used flow rates (10 mL/h) increased significantly from 19 ± 1.3 to 44 ± 72 mm Hg during long-term (≥7 days) epidural analgesia (P < 0.05, analysis of variance). Fixation by suture had no influence on tensile strength or perfusion pressure.

Conclusions: Epidural catheter use significantly increases the perfusion pressure and decreases the tensile strength.