From the Guidelines
To treat low bicarbonate in a patient on Continuous Veno-Venous Hemodialysis (CVVH), first increase the bicarbonate concentration in the replacement fluid to 35-40 mEq/L, as this is the most effective way to correct metabolic acidosis and improve patient outcomes, as suggested by 1. The goal of treatment is to gradually normalize bicarbonate levels to 22-26 mEq/L, as rapid correction can cause electrolyte imbalances and hemodynamic instability. Key considerations in managing metabolic acidosis in CVVH patients include:
- Increasing the dialysate flow rate to 25-35 mL/kg/hr if tolerated, ensuring adequate blood flow rates of 150-250 mL/min, and checking for proper filter function, as recommended by 1.
- Monitoring serum bicarbonate levels every 4-6 hours initially, then every 8-12 hours once stabilizing, to ensure that the treatment is effective and to avoid overcorrection.
- Addressing any underlying causes of acidosis, such as sepsis, tissue hypoperfusion, or lactic acidosis, as these conditions can worsen metabolic acidosis and negatively impact patient outcomes, as noted in 1.
- Using intravenous sodium bicarbonate as a slow infusion, typically starting with 50-100 mEq over 2-4 hours, with the dose adjusted based on the severity of the acidosis and patient's weight, if increasing the bicarbonate concentration in the replacement fluid is insufficient, as suggested by 1. Bicarbonate supplementation helps correct metabolic acidosis, which improves cardiac function, reduces vasopressor requirements, and optimizes enzyme function throughout the body, as noted in 1 and 1. It is also important to note that the correction of metabolic acidosis has been associated with increased serum albumin, decreased protein degradation rates, and increased plasma concentrations of branched chain amino acids and total essential amino acids, as reported in 1. Overall, the treatment of low bicarbonate in CVVH patients should prioritize the gradual normalization of bicarbonate levels, while also addressing underlying causes of acidosis and monitoring for potential complications, as recommended by 1 and 1.
From the Research
Treatment for Metabolic Acidosis in CVVH
The treatment for metabolic acidosis (low bicarbonate level) in a patient undergoing Continuous Veno-Venous Hemodialysis (CVVH) involves the use of bicarbonate-buffered replacement fluids.
- Bicarbonate-buffered replacement fluids can help correct metabolic acidosis by increasing the bicarbonate levels in the blood 2, 3, 4, 5.
- The use of bicarbonate-buffered replacement fluids can also help reduce the risk of cardiovascular events in critically ill patients with acute renal failure 5.
- In some cases, additional bicarbonate infusion may be needed to correct severe metabolic acidosis, especially in patients with lactic acidosis caused by biguanide intoxication 3.
Bicarbonate Replacement Fluids
- The concentration of bicarbonate in the replacement fluid can affect the correction of metabolic acidosis.
- A study found that switching from a high bicarbonate replacement fluid to a low bicarbonate replacement fluid can help normalize metabolic alkalosis during CVVH with regional citrate anticoagulation 6.
- Another study compared the effects of bicarbonate- and lactate-buffered replacement fluids on cardiovascular outcome in CVVH patients and found that bicarbonate-buffered replacement fluid was superior in normalizing acidosis without the risk of alkalosis 5.
Comparison with Lactate-Buffered Replacement Fluids
- Lactate-buffered replacement fluids can also be used in CVVH, but they may not be as effective in correcting metabolic acidosis as bicarbonate-buffered replacement fluids 2, 4, 5.
- A study found that lactate levels were significantly higher during dialysis with lactate-buffered solution than bicarbonate-buffered solution 4.
- Another study found that the use of lactate-buffered replacement fluid was associated with a higher number of hypotensive crises and cardiovascular events compared to bicarbonate-buffered replacement fluid 5.