The severance of epidural catheters

Four groups of Portex Minipack epidural sets were tested to measure the force required to sever the catheter on the needle bevel. The 18-gauge radio-opaque catheter was found to sever at a significantly lower applied force and to stretch significantly less before breaking than the 18-gauge clear catheter or either of the 16-gauge catheters. The other catheters tested had breaking strains of between 10-20 Newtons (1-2 kg force) and stretched by more than 30% of their lengths before breaking. It is suggested that these other catheters may therefore be a preferable alternative to the 18-gauge radio-opaque.