From the Guidelines
Acidosis during Continuous Renal Replacement Therapy (CRRT) can be decreased by using bicarbonate as a buffer in the dialysate or replacement fluid, especially in patients with lactic acidosis and/or liver failure, as recommended by the most recent and highest quality study 1. To decrease acidosis on CRRT, several strategies can be employed:
- Adjusting the dialysate or replacement fluid composition to include higher bicarbonate concentrations, typically 35-40 mEq/L instead of standard 32 mEq/L, can help increase the delivery of buffer and enhance acid clearance 1.
- Increasing the CRRT effluent dose to 25-35 mL/kg/hr can also enhance acid clearance, although the optimal dose may vary depending on the individual patient's needs and the specific CRRT modality being used.
- For severe acidosis, additional sodium bicarbonate can be administered as a separate infusion at 1-2 mEq/kg over 1-2 hours, or added directly to replacement fluids at concentrations of 5-10 mEq/L above baseline, as supported by the study 1.
- Adjusting blood flow rates to 150-200 mL/min can optimize clearance of acid metabolites, and regular monitoring of arterial blood gases every 4-6 hours is essential to guide therapy adjustments.
- The choice of modality (CVVH, CVVHD, or CVVHDF) can also impact acid-base management, with CVVHDF often providing more efficient correction of severe acidosis, although the study 1 does not provide a direct comparison of these modalities. It is also important to consider the potential complications of CRRT, such as electrolyte derangements and nutrient losses, as highlighted in the study 1, and to monitor patients closely to prevent these complications. Overall, the key to decreasing acidosis on CRRT is to use a combination of these strategies, tailored to the individual patient's needs, and to monitor patients closely to guide therapy adjustments, as recommended by the study 1.
From the Research
Tips to Decrease Acidosis on CRRT
To decrease acidosis on Continuous Renal Replacement Therapy (CRRT), several strategies can be employed:
- Adjusting fluid composition: This can be achieved by using bicarbonate-based solutions instead of lactate-containing fluids, as bicarbonate haemofiltration and dialysate fluids have been shown to offer better control of metabolic acidosis 2.
- Regulating CRRT dose: The dose of CRRT can be adjusted to optimize the removal of excess fluid and solutes, which can help to decrease acidosis 3, 4.
- Using separate intravenous infusions: Separate intravenous infusions can be used to mitigate and correct acid-base disturbances, such as administering bicarbonate to treat metabolic acidosis 3.
- Monitoring and adjusting prescription: Close monitoring of the patient's acid-base status and adjusting the CRRT prescription accordingly can help to prevent and treat acidosis 5.
Bicarbonate-Based Solutions
The use of bicarbonate-based solutions for CRRT has been shown to offer several benefits, including:
- Better control of metabolic acidosis: Bicarbonate haemofiltration and dialysate fluids have been shown to be superior to lactate in patients with acute kidney injury treated by CRRT 2.
- Rapid fall in lactate: The use of bicarbonate fluids has been shown to lead to a more rapid fall in lactate and greater improvement in base excess during CRRT 2.
- Improved acid-base stability: The use of bicarbonate-based solutions can help to improve acid-base stability and reduce the risk of acidosis 6.
CRRT Modalities
Different CRRT modalities can be used to achieve the desired goals of treatment, including:
- Continuous venovenous hemodialysis (CVVHD): This modality involves the use of a dialyzer to remove excess fluid and solutes from the blood 6.
- Continuous arteriovenous hemodialysis (CAVHD): This modality involves the use of a dialyzer to remove excess fluid and solutes from the blood, and is typically used in patients with high blood pressure 6.
- Continuous venovenous hemofiltration (CVVH): This modality involves the use of a hemofilter to remove excess fluid and solutes from the blood 4.