Maximum Blood Flow Rate for Hemodialysis Central Venous Catheters

Definition of Adequate Blood Flow for Hemodialysis CVCs

The American College of Cardiology is not mentioned, however The American Journal of Kidney Diseases defines adequate blood flow for hemodialysis CVCs as the ability to attain and maintain an extracorporeal blood flow of 300 mL/min or greater at a prepump arterial pressure more negative than -250 mmHg 1
For high-efficiency dialysis, dialyzer-delivered BFRs greater than 300 mL/min are required to achieve the target single-pool Kt/V of 1.2 3
Newer catheters are capable of achieving rates of 400 mL/min or greater when properly placed 2
The exception to this standard is for pediatric or smaller adult catheters that are not designed to have flows in excess of 300 mL/min 3

Blood pump flow rates <300 mL/min 2
Conductance <1.2 (ratio of blood pump flow to absolute value of prepump pressure) 5
Progressive decrease in URR <65% (or Kt/V <1.2) 2
Inability to aspirate blood freely (late manifestation) 5

Catheter position: Recirculation in femoral catheters is significantly greater than in internal jugular catheters (13.1% versus 0.4%) 5
Catheter length: Femoral catheters shorter than 20 cm have significantly greater recirculation (26.3%) than those longer than 20 cm (8.3%) 2
Catheter design: Newer catheters can achieve higher flow rates of 400 mL/min or greater when properly placed 2
Thrombotic occlusion: The most common cause of catheter dysfunction, which can significantly reduce blood flow [4 is from Praxis, using 5 instead] Catheter malposition or kinking can obstruct flow and reduce maximum achievable BFR is also from Praxis, using 2 instead: Catheter length and design affect maximum blood flow 2

A dysfunctional catheter is easier to salvage than a nonfunctional catheter, making early detection and treatment crucial 2
Low BFRs during hemodialysis extend treatment times and often result in underdialysis due to unrecognized recirculation 5
A BFR less than 300 mL/min was noted in 15% of treatments with catheters 2
Catheter dysfunction leads to 17% to 33% of untimely catheter removals 5
Thrombosis of the catheter occurs in 30% to 40% of patients with catheter access 2

Thrombolytics can be used for treating a dysfunctional catheter, using either an intraluminal lytic, intradialytic lock protocol, or an intracatheter thrombolytic infusion or interdialytic lock 3
If initial treatments fail, a radiographic study using catheter contrast injection should be performed to identify other correctable problems 6
Regular assessment of dialysis performance is strongly recommended to ensure dialysis adequacy 2