From the Guidelines
Hemodialysis treats metabolic acidosis by removing excess acid from the blood and adding bicarbonate, which helps restore normal acid-base balance, with a goal of maintaining serum bicarbonate at or above 22 mmol/L 1.
Mechanism of Action
Hemodialysis achieves this by using a dialysate fluid containing bicarbonate, typically at concentrations of 35-40 mEq/L, although higher concentrations can be used for more severe cases of acidosis. The process involves the diffusion of hydrogen ions out of the blood and bicarbonate ions into the blood, effectively raising the patient's serum bicarbonate level.
Clinical Practice Guidelines
According to clinical practice guidelines, the correction of metabolic acidemia by maintaining serum bicarbonate at or above 22 mmol/L should be a goal of the management of individuals undergoing hemodialysis 1. This can be achieved by higher dialysate bicarbonate concentrations and/or oral supplementation with bicarbonate salts. An oral dose of sodium bicarbonate, usually about 2 to 4 g/d or 25 to 50 mEq/d, can be used to effectively increase serum bicarbonate concentrations.
Treatment Outcomes
The correction of acidemia due to metabolic acidosis has been associated with several beneficial outcomes, including increased serum albumin, decreased protein degradation rates, and increased plasma concentrations of branched chain amino acids and total essential amino acids 1. Furthermore, raising the serum bicarbonate level has been associated with fewer hospital stays in patients undergoing continuous peritoneal dialysis.
Hemodialysis Session Duration
While the duration of hemodialysis sessions can vary, guidelines recommend a minimum of 3 hours per session for patients with low residual kidney function undergoing thrice weekly hemodialysis 1. Additional sessions or longer treatment times may be considered for patients with large weight gains, high ultrafiltration rates, or poor metabolic control, including metabolic acidosis.
Key Considerations
- Monitoring and adjusting dialysate bicarbonate concentration based on the severity of acidosis and patient response.
- Oral bicarbonate supplementation as an adjunct to hemodialysis for managing metabolic acidosis.
- Regular monitoring of serum bicarbonate levels to ensure that targets are being met and to adjust treatment as necessary.
From the Research
Mechanism of Hemodialysis in Treating Metabolic Acidosis
- Hemodialysis helps to treat metabolic acidosis by removing excess acid from the blood and replenishing bicarbonate levels 2, 3.
- The process involves the use of a dialysate solution that contains bicarbonate, which helps to neutralize excess acid in the blood 4.
- The bicarbonate concentration in the dialysate solution can be adjusted to achieve the desired level of acid-base balance in the patient 2.
Effects of Hemodialysis on Acid-Base Balance
- Studies have shown that hemodialysis can significantly improve acid-base balance in patients with metabolic acidosis, as evidenced by increases in blood pH and bicarbonate levels 2, 3.
- However, the individual selection of bicarbonate in the dialysate solution may not permanently improve acid-base balance in all patients, highlighting the need for personalized treatment approaches 2.
- The use of oral bicarbonate supplementation and other treatments, such as increased fruit and vegetable intake, may also be necessary to maintain optimal acid-base balance in patients with metabolic acidosis 5.
Importance of Monitoring and Adjusting Treatment
- Regular monitoring of blood pH, bicarbonate levels, and other parameters is essential to ensure that hemodialysis is effectively treating metabolic acidosis 2, 4.
- Adjustments to the dialysate solution, oral supplementation, and other treatments may be necessary to achieve and maintain optimal acid-base balance in patients with metabolic acidosis 2, 5.
- Further research is needed to determine the optimal target serum bicarbonate levels and treatment strategies for patients with metabolic acidosis 3, 5.