What if using F180 (Fresenius 180) hemodialysis in addition to Continuous Renal Replacement Therapy (CRRT)?

Using F180 Hemodialysis in Addition to CRRT

Direct Answer

Combining intermittent hemodialysis (such as the Fresenius F180) with CRRT is not a standard practice and lacks evidence-based support for routine use, but hybrid or sequential therapy (alternating between intermittent HD and CRRT) may be considered in specific clinical scenarios requiring rapid solute clearance followed by sustained hemodynamic stability.

Clinical Context and Evidence

Standard Practice Patterns

The available evidence does not support routinely running intermittent hemodialysis simultaneously or as an adjunct to ongoing CRRT 1. The consensus guidelines emphasize choosing between modalities based on patient characteristics rather than combining them 1.

When Hybrid/Sequential Therapy May Be Appropriate

Severe hyperammonemia represents the clearest indication for sequential therapy:

• Intermittent HD achieves 50% reduction in ammonia levels within 1-3 hours, making it superior for rapid initial clearance 2
• Following initial HD, transitioning to CRRT (specifically high-dose CVVHD) controls ammonia rebound and provides sustained clearance 2
• This combination is particularly recommended for hemodynamically unstable neonates who require both rapid ammonia reduction and cardiovascular stability 2

Acute liver failure with severe metabolic derangements may warrant consideration:

• CRRT provides superior hemodynamic stability in critically ill liver failure patients 3
• However, if rapid correction of specific toxins or severe electrolyte abnormalities is needed, initial brief HD followed by CRRT transition could be considered 3

Evidence Against Routine Combination

Survival outcomes do not favor combining modalities:

• A 2022 secondary analysis of AKIKI and IDEAL-ICU trials (543 patients) found CRRT as first modality was associated with worse 60-day survival compared to IHD (weighted HR 1.26,95% CI 1.01-1.60) 4
• In less severely ill patients (SOFA 3-10), IHD showed significantly better survival than CRRT (weighted HR 1.82,95% CI 1.01-3.28) 4
• No evidence suggests that adding one modality to another improves outcomes beyond selecting the appropriate single modality 4

Operational considerations argue against simultaneous use:

• Each modality requires dedicated vascular access, increasing thrombosis and infection risk 1
• CRRT already provides adequate solute clearance when properly dosed at 35 mL/kg/hour for CVVH or 20-25 mL/kg/hour effluent for other modalities 1, 5
• Modern high-flux and super high-flux filters in CRRT provide sustained middle molecule clearance, reducing theoretical advantages of adding intermittent HD 6

Practical Algorithm for Modality Selection

Choose intermittent HD (including F180) when:

• Patient is hemodynamically stable 5
• Rapid solute removal is required (severe hyperkalemia, toxic ingestions, extreme hyperammonemia) 2, 5
• Resources or staffing limit CRRT availability 1

Choose CRRT when:

• Hemodynamic instability or high vasopressor requirements exist 5, 3
• Cerebral edema or increased intracranial pressure is present 5
• Continuous toxin removal is needed 5
• Severe liver failure with AKI 3

Consider sequential therapy (HD → CRRT) when:

• Ammonia >500 μmol/L with encephalopathy requiring immediate reduction followed by sustained control 2
• Hemodynamically unstable neonates with hyperammonemia 2
• Initial rapid correction needed but patient cannot tolerate sustained intermittent HD 2

Critical Pitfalls to Avoid

Do not delay definitive single-modality therapy by attempting to set up combination therapy without clear indication 2, 5. The duration of metabolic derangement (particularly hyperammonemic coma) before dialysis initiation is the most important prognostic factor, not the specific modality chosen 2.

Avoid using CRRT in stable patients who could tolerate intermittent HD, as recent evidence suggests potential harm in less severely ill patients 4.

Do not assume combining modalities increases clearance beyond what properly dosed single-modality therapy achieves 1, 7. A minimum Kt/V of 1.2 three times weekly or CVVH at 35 mL/kg/hour provides adequate dosing 1.

Monitor for access complications if sequential therapy is used, as repeated connection/disconnection increases infection risk 1.