Access Recirculation Measurement in Variable Temporary Central Catheters by Low-flow Two-needle Method for CRF

Kim, Young Dae; Kim, Sung Rok

Abstract

Blood recirculation in hemodialysis access is one of the factors decreasing dialysis efficiency. The purpose of this study was to evaluate access recirculation by the site of veins, length of catheters using the low-flow two-needle method in recently inserted temporary central vein catheterization used for hemodialysis in patients with chronic renal failure, and evaluate the reproducibility of low-flow method. A total of 56 measurements were performed in 15 chronic renal failure patients harboring 25 different catheters. Mean blood recirculation for the 56 measurements was 11.1+/-7.9%, it was significantly higher in the femoral catheters than in the subclavian catheters, reaching respective means of 17.9+/-6.5%, 5.2+/-2.3%. Blood recirculation rate was not different between 13.5cm and 19.5cm long subclavian catheters(5.3+/-2.7%, versus 5.5+/-1.7%), but was significantly higher in 13.5cm than in 19.5cm long femoral catheters(20.3+/-6.1% versus 13.3+/-4.8%, P=0.0067). Mean URR for the 56 dialysis sessions was 52.7+/-10.3%, it was significantly higher for sessions performed with subclavian than with femoral catheters(56.0+/-9.8% versus 48.8+/-9.7%, P=0.0088). An overall weak negative correlation of -0.42 was observed between blood recirculation and URR; the correlation was stronger for the sub-group of 19.5cm long femoral catheters, reaching -0.63. The obtained results were reproducible with a mean difference between two measurements in 18 cases of only 3.62+/-5.3% and a correlation of 0.68. The difference between blood recirculation rates in temporary femoral and subclavian catheters may be consequent to an anatomical factor. It may relate to the size of the vein, the blood probably having less possibility to recirculate near the tip of the catheter in a wider vein. In conclusion, femoral catheters particularily the shorter ones, are associated with significantly higher blood recirculation, and thus may consequently reduce the dialysis efficiency. In patients for whom dialysis dose is a priority, such as cases of intoxication for whom rapid and efficient toxic substance removal is mandatory, we think the subclavian catheters may become a first choice.