Comparative evaluation of straight and curved extension dialysis catheters for continuous renal replacement therapy in dogs with acute kidney injury

Background: A patent dual-lumen dialysis catheter is one of the basic requirements for efficient extracorporeal (EC) therapy. Aims: The objective of this study was to measure the resistance to blood flow offered by straight and curved-extension dual-lumen dialysis catheters used for continuous renal replacement therapy (CRRT). Methods: Twenty dogs suffering from acute kidney injury (AKI) were subjected to CRRT. The dogs were allocated randomly to Group-I (curved extension catheter, n=12) or Group II (straight extension catheter, n=8), based on the type of dual-lumen catheter used in CRRT. The catheter outflow and inflow pressures were recorded at blood pump speeds of 50 ml/min and 99-100 ml/min. Data were tested for normality, and differences in mean inflow and outflow catheter resistances were evaluated for statistical significance using independent samples t-tests. Results: Straight extension catheters offered lower inflow resistance than curved extension catheters at both 50 ml/min (41.50 ± 5.84 mm Hg vs. 63.75 ± 6.88 mm Hg, P=0.03) and 99-100 ml/min (63.00 ± 8.11 mm Hg vs. 86.92 ± 7.02 mm Hg, P=0.04) blood flow rates. Straight extension catheters also offered lower outflow resistance than curved catheters at 99-100 ml/min blood flow rate (-94.12 ± 7.91 mm Hg vs. - 128.25 ± 7.56 mm Hg, P=0.01; the negative signs only indicate the direction of blood flow). Conclusion: These findings suggest that straight-extension dual-lumen dialysis catheters perform better than the curved model in extracorporeal renal replacement therapy by considering their lower resistance to blood flow.