The mechanical properties of intact and traumatized epidural catheters

Comparative data on the mechanical properties of epidural catheters used cl inically are not available. We performed a controlled laboratory investigat ion to assess the mechanical performance of three different intact or traum atized catheter types (Polyurethane, clear nylon, and radiopaque nylon cath eters, designed for 18-gauge Tuohy needles). We studied a control (intact) and two trauma groups (needle bevel and surgical blade). Catheters were loa ded to their breaking points by using a Lloyd LS500 material testing machin e (Lloyd, Southampton, UK). Maximal load and extension values before breaka ge were measured, and modulus of elasticity and toughness values were calcu lated. Intact polyurethane catheters did not break within the limits of the experimental study (extension up to 3 times the original length of a speci men). The toughness values obtained from polyurethane and clear nylon cathe ters were significantly higher than those for the radiopaque catheters in i ntact specimens (P < 0.05). In the traumatized groups, polyurethane cathete rs had the highest toughness values (P < 0.05). Modulus of elasticity value s were higher in both control and trauma groups of the radiopaque catheters when compared with the polyurethane and clear nylon catheters, which indic ates a higher stiffness to elastic deformation (P < 0.05). In conclusion, p olyurethane catheters are the most durable catheter type to tensile loading , either intact or traumatized. Mechanical properties can be used to predic t complications related to the clinical use of these catheters. Implication s: Using a computer-assisted material testing machine, we studied the mecha nical properties of three different types of epidural catheters, either int act or traumatized, in a blinded, controlled study. This information may be vital to clinicians who implant epidural catheters by helping them choose a catheter that has the lowest probability of failure.