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Tensile Strength Decreases and Perfusion Pressure of 3-Holed Polyamide Epidural Catheters Increases in Long-Term Epidural Infusion
  1. Pascal Kim, MD*,
  2. Urs Meyer, PhD,
  3. Guido Schüpfer, MD, PhD*,
  4. Roman Rukwied, PhD*,,
  5. Christoph Konrad, MD, PhD* and
  6. Helmut Gerber, MD, PhD*
  1. From the *Department of Anesthesiology and Operative Intensive Care, Kantonsspital Lucerne, Switzerland;
  2. Textile Machinery, ETH Zurich, Switzerland; and
  3. Department of Anesthesiology, Medical Faculty Mannheim, Heidelberg University, Germany.
  1. Address correspondence to: Pascal Kim, MD, Department of Anesthesiology and Operative Intensive Care, Kantonsspital Lucerne, CH-6000 Lucerne 16, Switzerland (e-mail:{at}


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.

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  • Drs. Kim and Meyer equally contributed to this work.

  • Dr. Meyer is professor emeritus for Textile Machinery, ETH Zurich, Switzerland.