What are the key parameters in hemodialysis, including Blood Flow Rate (BFR), Dialysate Flow Rate (DFR), treatment duration, heparin dose, dialysate composition, and Ultrafiltration (UF) rate?

Key Parameters in Hemodialysis

The essential hemodialysis parameters include blood flow rate (BFR) of 250-400 mL/min, dialysate flow rate (DFR) of 500 mL/min, treatment duration of 3-4 hours thrice weekly, heparin dosing of 25-30 units/kg followed by 1,500-2,000 units/hour, dialysate composition tailored to individual needs, and ultrafiltration rate not exceeding 10 mL/h/kg to optimize patient outcomes.

Blood Flow Rate (BFR)

• Target BFR should be ≥250 mL/min as lower rates are associated with higher all-cause mortality 1
• Typical BFR ranges from 250-400 mL/min for adults, with higher rates providing better clearance but potentially causing more symptoms 2
• BFR is limited by vascular access function and patient tolerance 3
• Inadequate BFR can significantly reduce delivered dialysis dose and contribute to treatment failure 3

Dialysate Flow Rate (DFR)

• Standard DFR is typically 500 mL/min in most dialysis units 4
• The optimal ratio of blood flow to dialysate flow (QB:QD) should be maintained at 1:2 for well-balanced dialysis efficiency 4
• DFR can be reduced to 400 mL/min when blood flow is ≤200 mL/min without significantly affecting dialysis efficiency 4
• Inadequate dialysate flow can reduce effective clearance and contribute to underdialysis 3

Treatment Duration

• Standard hemodialysis schedule is three times weekly with sessions lasting 3-4 hours 5
• Treatment time must accurately reflect the exact amount of time during which diffusion occurred at the prescribed blood and dialysate flow rates 3
• Interruptions during treatment (equipment alarms, needle replacement, dialyzer clotting) reduce actual dialysis time 3
• Treatment time should be sufficient to achieve adequate fluid removal without excessive ultrafiltration rates 5

Heparin Dosing

• For extracorporeal dialysis, the recommended dose is 25-30 units/kg followed by an infusion rate of 1,500-2,000 units/hour 6
• Heparin prevents clotting of the dialyzer during treatment, which would otherwise reduce effective dialyzer surface area 3
• Heparin dosing must be individualized based on patient's bleeding risk and clotting tendency 6
• Inadequate anticoagulation can lead to dialyzer clotting and reduced clearance 3

Dialysate Composition

• Dialysate composition includes sodium, potassium, calcium, magnesium, chloride, bicarbonate, and glucose 5
• Bicarbonate concentration is necessary to prevent or correct metabolic acidosis, which can increase protein catabolism 7
• Sodium concentration typically ranges from 135-145 mEq/L and affects fluid shifts and blood pressure stability 5
• Potassium concentration varies (usually 1-3 mEq/L) based on patient's predialysis potassium level 5

Ultrafiltration (UF) Rate and Volume

• UF rate should not exceed 10 mL/h/kg body weight, as higher rates are associated with increased mortality 8
• UF volume is determined by interdialytic weight gain and target dry weight 3
• Excessive ultrafiltration can lead to intradialytic hypotension and increased mortality 5
• Fluid removal should be individualized based on cardiovascular stability 5

Dialysis Adequacy Measures

• Target single-pool Kt/V should be 1.4 per session for thrice-weekly hemodialysis, with minimum delivered dose of 1.2 5
• For schedules other than thrice weekly, target standard Kt/V is 2.3 volumes per week 5
• Kt/V represents fractional urea clearance and is the most precise measure of dialyzer effect on patient survival 5
• Monthly measurement of delivered dose is recommended to ensure adequacy 3

Common Pitfalls to Avoid

• Targeting minimum values as goals can result in many sessions falling below the threshold; always target higher (Kt/V of 1.4) 5
• Inadequate blood sampling techniques can lead to inaccurate Kt/V calculations 3
• Ignoring treatment time reductions due to late starts or early terminations 3
• Failing to account for access recirculation, which reduces effective clearance 3
• Focusing solely on small-solute clearance while overlooking fluid balance, blood pressure control, and nutritional status 5

Monitoring Requirements

• Delivered dose of hemodialysis should be measured at least monthly 5
• Increase measurement frequency when patients are non-compliant, when problems in delivery occur, or when prescriptions are modified 5
• Proper BUN sampling techniques are crucial for accurate Kt/V calculation 3
• Monitor ultrafiltration rate to avoid rapid fluid removal 5