Epidural Catheter Reconnection

Abstract

Background An in vitro model of epidural catheter contamination was used to determine if disconnected catheters can be safely reconnected. Methods Epidural catheters were filled with brain-heart infusion (BHI) broth or preservative-free saline containing 5 micrograms/ml fentanyl. Escherichia coli, Pseudomonas aeruginosa, or Staphylococcus aureus (1.10(5) colony-forming units) was injected into the initial 1.1 +/- 0.24 inch (2.75 +/- 0.60 cm) of the catheters. To study the effect of bacteria settling in a vertically oriented catheter on the advancement of bacteria along the catheter, bacteria were incubated with catheters in the vertical and the horizontal positions. To determine if bacteria are swept further into a catheter when fluid in it is displaced, catheters were inclined 30 degrees and the fluid in them was allowed to drain from the distal end to various extents. Bacteria were incubated with the catheter held horizontally. After incubation, the catheters were serially sectioned, and the resulting segments were eluted with buffered saline-containing gelatin (BSG), which was collected on BHI agar plates for colony counts. This determined if a segment of the catheter remained internally sterile distal to the point of disconnection. Effectiveness of decontaminating the exterior of the catheter was also tested as follows: Catheters (n = 10) were first immersed in BSG containing 1.10(5) S, aureus, immediately immersed in betadine for 2 min, exposed to air for 3 min, cut with a sterile instrument, and reconnected to a sterile screw cap catheter connector. Reconnected catheters were perfused with 10 ml BSG for 1 hr. Collected perfusate (100 microliters) was removed for direct colony count; the remaining perfusate was mixed with an equal volume of BHI and incubated overnight. A 100 microliters aliquot of BHI-BSG mixture was sampled the next day. No bacteria were cultured from either the perfusate or BHI-BSG mixture. Results Eight hours after contamination, as long as the fluid in the catheter was static, no bacteria were detected more than 13 inches (32.5 cm) from the contaminated end of catheters filled with BHI and no more than 8 inches (20 cm) from the end of those filled with fentanyl solution. This finding was not affected by incubation of the catheter in the vertical position. Fluid displacement less than 8 inches (20 cm) had no effect on dissemination, but when fluid was displaced 13 inches (32.5 cm), bacteria were found at the end of the catheter, 35 inches (87.5 cm) away. No bacteria were recovered from the perfusate of reconnected catheters after the catheters were cleaned with betadine and cut with a sterile instrument. Conclusions There may be an area distal to the disconnected end of an epidural catheter where its interior remains sterile for at least 8 hr. Such an area exists only when the fluid in the catheter remains static. Furthermore, the exterior of the catheter can be adequately cleaned to prevent bacteria from entering the catheter when reconnected at that point.