From the Guidelines
The replacement fluid rate in Continuous Renal Replacement Therapy (CRRT) should be calculated based on the patient's body weight, with a standard dosing of 20-25 mL/kg/hour, as recommended by the KDIGO guidelines 1. For an average 70 kg patient, this translates to approximately 1400-1750 mL/hour. The rate is adjusted according to the specific CRRT modality being used (such as CVVH, CVVHD, or CVVHDF), the patient's clinical condition, and treatment goals. Some key points to consider when calculating the replacement fluid rate include:
- The patient's fluid status and electrolyte balance
- The presence of severe metabolic derangements or high catabolic states (like sepsis)
- The need for individualization of the intensity of CRRT or IHD to meet a patient’s requirements for maintenance of electrolyte and fluid balance 1
- The importance of regularly reassessing the patient's fluid status, electrolyte balance, and acid-base status to fine-tune the replacement rate
- The composition of replacement fluid, which should contain physiologic concentrations of electrolytes like sodium, potassium, calcium, magnesium, chloride, and bicarbonate, customized based on the patient's specific needs 1. This calculated approach ensures adequate solute clearance while maintaining appropriate fluid balance and electrolyte homeostasis during the continuous therapy.
From the Research
Calculation of Replacement Fluid Rate in CRRT
The calculation of replacement fluid rate in Continuous Renal Replacement Therapy (CRRT) is crucial for effective fluid management and patient outcomes.
- The replacement fluid rate is typically calculated based on the patient's fluid balance goals and net ultrafiltration rate 2.
- Net ultrafiltration rate is the rate at which fluid is removed from the patient, and it is an important factor in determining the replacement fluid rate 2.
- The optimal method of fluid management during CRRT is still unclear, but observational data suggest a U-shape relationship between net ultrafiltration rate and mortality 2.
- The type of buffer used in the replacement fluid can also affect the acid-base balance and clinical outcome of the patient 3.
- Bicarbonate-buffered replacement fluids have been shown to improve acid-base status and reduce cardiovascular events better than lactate fluids 3.
Factors Affecting Replacement Fluid Rate
Several factors can affect the replacement fluid rate in CRRT, including:
- Patient's fluid balance goals 2
- Net ultrafiltration rate 2
- Type of buffer used in the replacement fluid 3
- Patient's underlying medical condition, such as liver disease 4, 5
- Presence of hemodynamic instability 4, 6
Clinical Considerations
Clinicians should be aware of the importance of individualized prescription and balance control in CRRT 3.
- The quality control for sterility, physical properties, and balance control are vitally important in CRRT 3.
- Anticoagulation should be considered in patients with repeated circuit clotting, as it can improve CRRT circuit survival without an obvious increase in bleeding or blood transfusion requirement 5.