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Assessment of Temporary Dialysis Catheter Performance on the Basis of Flow and Pressure Measurements In Vivo and In Vitro

The efficiency of hemodialysis treatments depends on catheter performance and, consequently, on effective blood flow that can be achieved at maximum extracorporeal pressures. Differences in effective and displayed flow were determined with ultrasound dilution technology, and a mathematical correction function for the MultiFiltrate hemodialysis machine was developed. This algorithm was used to calculate effective blood flow during treatment from displayed flow and arterial pressure. To assess catheter performance over time, we measured effective blood flow as function of extracorporeal pressure in 11 uncuffed, tunneled hemodialysis catheters with shotgun design. Pressure and flow profiles of the catheters were determined, and pressure symmetry was measured. To assess flow resistance over time, pressure trends of the catheters at different blood flow rates were measured for each patient over a mean period of 6.1 ± 3.0 days. Increases in flow resistance during the study period were found to be small. Mean arterial pressure decreased from –185 mm Hg to –200 mm Hg, and mean venous pressure increased from 197 mm Hg to 215 mm Hg. Effective flow did not change significantly during the study. In conclusion, all catheters investigated easily provided effective flows above 450 mL/min over the study period at maximum extracorporeal pressures below ±300 mm Hg.