The effect of open-end versus closed-end epidural catheter design on injection pressure and dye diffusion under various programmed intermittent epidural delivery rates: an in vitro study

Background: Epidural catheter design may impact injection pressure and analgesic outcomes under programmed intermittent epidural bolus regimens. This in vitro study aimed to compare the injection pressure and dye diffusion between open-end and closed-end catheters at varying delivery rates.

Methods: The injection pressure and dye diffusion distance and area were measured at five delivery rates (120, 240, 360, 480, and 600 mL/h) through three epidural catheters (OE-3, open-end, three lateral ports; CE-3, closed-end, three lateral ports; OE-0, open-end, single port). A two-way analysis of variance with the Bonferroni post hoc test was applied for comparisons between the catheter groups and delivery rates.

Results: Forty-five pressure tests and 45 dye diffusion measurements were performed. The peak pressure was significantly higher with the closed-end catheter at 240, 360, 480, and 600 mL/h delivery rates (P<0.025). The diffusion distance was shorter at all delivery rates (P<0.001). At 360 mL/h, the diffusion area was larger with CE-3 than with OE-0 catheters, but at 600 mL/h it was smaller with CE-3 than with OE-3 catheters (CE-3 vs. OE-0 at 360 mL/h, P<0.025; CE-3 vs. OE-3 at 600 mL/h, P<0.025).

Conclusions: At high delivery rates (>360 mL/h), the closed-end catheter had no advantages over the open-end catheters in diffusion distance or area. When using a close-ended catheter and high delivery rates, the peak pressure generated might trigger the occlusion alarm.