Access recirculation in temporary hemodialysis catheters as measured by the saline dilution technique

Ultrasound dilution technology is emerging as the standard for measuring access recirculation and blood flow in hemodialysis patients. In temporary dialysis catheters, studies using the traditional two-needle urea method have suggested that short femoral catheters are associated with an unacceptably high degree of recirculation. This problem has never been assessed using ultrasound dilution technology. We performed a prospective observational study of consecutive patients undergoing dialysis through a temporary catheter. Measurements were made on 49 catheters; 10 catheters were excluded because poor flow necessitated reversal of the dialysis ports. Thirty-nine catheters in 33 patients were included in this analysis, of which 26 catheters were located in the femoral vein, and 13 catheters, in the internal jugular vein. Dialyzer blood flow was adjusted to give an ultrasonic flow rate of 250 mL/min (actual mean blood flow, 234.3 mL/min; 95% confidence interval [CI], 228 to 241). Overall mean recirculation rate was 8.9% (95% CI, 4.8 to 13.0). Multivariate analysis showed catheter location and length to be independent predictors of recirculation. Blood flow (within the range tested), duration into dialysis, time since catheter insertion, cardiac rhythm, and catheter type had no significant effect on recirculation rates. Recirculation in femoral catheters (13.1%) was significantly greater than that in internal jugular catheters (0.4%; P: < 0.001). Femoral catheters shorter than 20 cm had significantly greater recirculation (26.3%) than those longer than 20 cm (8.3%; P: = 0.007). We conclude that temporary femoral catheters shorter than 20 cm are associated with increased recirculation rates. In addition, when dialysis dose delivery is a priority, locating the temporary catheter in the internal jugular vein is an advantage.