Biomechanical effects of length and angle of the subcutaneous tunnel on epidural catheter stability in a porcine model.

Epidural catheter dislocation can lead to severe complications, especially in anticoagulated patients. Fixation techniques vary, and the role of subcutaneous tunneling and the biomechanical effects of length or angle towards dislocation forces of the tunnel remain unknown. This in vitro study evaluated the contribution of length and angle of subcutaneous tunneling (2-5 cm at six various angles relative to dislocation force) compared to different adhesive fixation methods (transparent film dressing, adhesive strips 10-20 cm) on epidural catheter stability. Dislocation forces were measured in a porcine skin model using a motorized traction system and a force transducer. The mean dislodgement force for tunneled catheters was 0.86 ± 0.3 N. This was significantly lower than the forces measured using transparent film dressing (9.89 ± 2.65 N; p < 0.001) or adhesive strips (10 cm: 8.03 ± 2.3 N; 20 cm: 10.92 ± 0.84 N; all p < 0.001). Tunnel length and angle had no significant impact on catheter stability whereas increasing the length of the adhesive strip significantly increased the dislodgement force (p < 0.001). In conclusion, subcutaneous tunneling of epidural catheters provides limited mechanical benefit on catheter stability under standardized conditions in a porcine model whereas adhesive fixation generates substantially greater resistance to immediate catheter dislocation.