An in vitro evaluation of flow from multihole epidural catheters during continuous infusion with four different infusion pumps

We have observed in vitro the distribution of flow from 10 identical multih ole epidural catheters during continuous infusion with four different infus ion pumps. The pumps chosen were the B Braun Perfusor Secura FT syringe dri ver and three volumetric infusion pumps utilising different pumping mechani sms (Dekra 3000 BL, Graseby 500 and CADD-Prizm). These pumps infused 0.9% s aline through each catheter at 5 ml.h(-1), 15 ml.h(-1), 50 ml.h(-1) and 99 ml.h(-1) for 3 min. The number of holes through which flow occurred and the catheter hole where flow predominated during each test were recorded. The pressure waveform generated during each infusion was displayed and the peak pressure recorded. In 38 of the 160 tests (24%) the largest proportion of flow was seen at the hole closest to the catheter tip. The CADD pump genera ted multihole flow during significantly more tests (p < 0.0001) than the ot her pumps and produced significantly higher driving pressures (p < 0.001) a t all infusion rates compared with the Graseby and Perfusor pumps. The CADD was the only pump to produce flow from all three holes of the catheter at 5 ml.h(-1).