Lactate Clearance by CRRT vs Hemodialysis
Both CRRT and intermittent hemodialysis can clear lactate from the blood, but CRRT provides more hemodynamically stable lactate removal in critically ill patients, while intermittent hemodialysis achieves faster clearance rates at the cost of greater hemodynamic instability.
Key Clinical Considerations
Buffer Selection in CRRT
The most critical issue is not whether CRRT or hemodialysis clears lactate better, but rather avoiding lactate-buffered dialysate in patients with lactic acidosis or liver failure 1. Bicarbonate-buffered solutions are preferred in patients with lactic acidosis and/or liver failure 1 because:
- Lactate-buffered dialysate can worsen acidosis in patients with existing lactic acidosis or hepatic dysfunction 1
- Lactate-free dialysate provides more rapid control of acidosis than lactate-buffered solutions 2
- Both lactate and bicarbonate buffers can correct metabolic acidosis in most CRRT patients without these conditions 1
Lactate Clearance Efficacy
CRRT Characteristics:
- Lactate clearance increases with higher CRRT doses (20 to 45 mL/kg/h) 3
- Rate of lactate clearance increases with both higher CRRT doses and higher initial lactate levels 3
- Provides continuous, gradual lactate removal with better hemodynamic tolerance 4
- Mean arterial pressure remains more stable with CRRT 4
Intermittent Hemodialysis Characteristics:
- Achieves greater improvement in laboratory parameters including lactate 5
- Provides faster clearance rates per session 5
- Associated with statistically significant decreases in mean arterial pressure 5, 4
- Requires hemodynamic stability to tolerate treatment 4
Clinical Algorithm for Modality Selection
Choose CRRT when:
- Patient has hemodynamic instability (hypotension, high vasopressor requirements)
- Lactic acidosis is present (use bicarbonate-buffered dialysate)
- Liver dysfunction exists (use bicarbonate-buffered dialysate)
- Continuous metabolic control is needed
Choose Intermittent Hemodialysis when:
- Patient is hemodynamically stable
- Rapid toxin removal is required (e.g., metformin-associated lactic acidosis) 6
- Intermittent treatment schedule is acceptable
- Resources for continuous therapy are unavailable
Important Caveats
The contribution of extracorporeal lactate clearance to overall lactate metabolism is relatively small 3. The hemofilter's contribution to total body lactate clearance may be negligible compared to endogenous metabolism. Therefore, treating the underlying cause of lactate elevation (shock, sepsis, tissue hypoxia) remains paramount - dialysis modality selection should not distract from addressing the primary pathology.
Mortality outcomes are similar between CRRT and IHD 5, 7, 4, suggesting that modality choice should be based on hemodynamic tolerance and clinical context rather than survival benefit alone.
Patients receiving IHD have higher rates of long-term dialysis dependence after hospital discharge 7, though this may reflect selection bias toward more unstable patients receiving CRRT.