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

Abstract

SummaryWe have observed in vitro the distribution of flow from 10 identical multihole epidural catheters during continuous infusion with four different infusion pumps. The pumps chosen were the B Braun Perfusor Secura FT syringe driver and three volumetric infusion pumps utilising different pumping mechanisms (Dekra 3000 BL, Graseby 500 and CADD-Prizm). These pumps infused 0.9% saline through each catheter at 5 ml.h À1 , 15 ml.h À1 , 50 ml.h À1 and 99 ml.h À1 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 generated multihole flow during significantly more tests (p`0.0001) than the other pumps and produced significantly higher driving pressures (p`0.001) at 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 À1 .

Variability of performance of wound infusion catheters

“…Despite the differences between our study and studies of multi‐hole epidural catheters reported previously (McAtamney et al. ; Fegley et al. ), our finding of uneven distribution of flow are similar.…”

“…Similar previous studies evaluated epidural catheters with a small number of holes, and at the relatively high injection rates that characterize intermittent bolus dosing (McAtamney et al. ; Fegley et al. ).…”

“…One of those studies (McAtamney et al. ) evaluated the effect of different pump designs on the distribution of flow through the three holes of a commercial epidural catheter, and the authors determined that the pump that generated the highest peak infusion pressures (a continuous ambulatory drug delivery device with pulsatile flow creating high pressure spikes) was most likely to achieve flow through all three holes. Although the authors of an earlier study (Power & Thorburn ) reported that at low pressures most flow from these catheters went through the two holes closest to the syringe, McAtamney et al.…”

Catheter Orifice Configuration Influences the Effectiveness of Continuous Peripheral Nerve Blockade

“…* 2011 American Society of Regional Anesthesia and Pain Medicine enhances these benefits 16,20,22Y26 Similarly, the benefits of intermittent bolus regimens may apply only to multiorifice catheters. 8,15,27 Flow from a multiorifice catheter has been shown to depend on the flow rate: below 80 mL/hr, multiorifice catheters function like single-orifice catheters. 15 Therefore, the present results may not be generalizable to infusion-only regimens:…”

“…8,15,27 In other words, to realize the benefits of the multiorifice design, flow rates greater than 100 mL/hr need to be deliveredVflow rates that can be delivered only with intermittent bolus regimens. Extrapolating from in vitro experiments, the regimen used in the present study likely resulted in tripleorifice flow during the manual primary local anesthetic bolus (9400 mL/hr), double-orifice flow during on-demand boluses (150 mL/hr), and single-orifice flow during the background infusion (2 mL/hr).…”