How to manage mixed acidosis in a dialysis patient?

From the Guidelines

Managing mixed acidosis in a dialysis patient with a pH of 7.16, PCO2 of 46, and bicarbonate of 17 requires immediate correction of metabolic acidosis by maintaining serum bicarbonate at or above 22 mmol/L. To achieve this, the following steps can be taken:

• Normalization of the predialysis or stabilized serum bicarbonate concentration can be achieved by higher dialysate bicarbonate concentrations, typically around 38 mmol/L, as shown in studies 1.
• Oral supplementation with bicarbonate salts, such as sodium bicarbonate, can also be effective, with a usual dose of about 2 to 4 g/d or 25 to 50 mEq/d 1.
• It is essential to monitor serum bicarbonate levels regularly, at monthly intervals, to ensure that the target level is maintained.
• Correction of acidemia due to metabolic acidosis has been associated with several benefits, including increased serum albumin, decreased protein degradation rates, and increased plasma concentrations of branched chain amino acids and total essential amino acids 1.
• Additionally, addressing the respiratory component of mixed acidosis is crucial, which may involve treating underlying causes such as pneumonia or bronchoconstriction, and providing respiratory support when necessary.
• Regular monitoring of arterial blood gases, electrolytes, and clinical status is necessary to guide therapy adjustments and ensure that the patient's condition is improving.

From the Research

Managing Mixed Acidosis in Dialysis Patients

• Mixed acidosis in dialysis patients can be challenging to manage, but several strategies can help mitigate this condition.
• A study by 2 suggests that individualized adjustment of dialysate bicarbonate concentration according to pre- and post-dialysis total carbon dioxide (TCO2) values can reduce acid-base imbalances in hemodialysis patients.
• Another study by 3 highlights the importance of monitoring dialysate bicarbonate concentration, as low levels can exacerbate metabolic acidosis in patients undergoing sorbent system hemodialysis.
• Respiratory acidosis can also occur in dialysis patients, particularly those with ventilatory limitations, as seen in a case report by 4, which emphasizes the need to consider excess CO2 production in patients with respiratory disorders associated with dialysis.

Treatment Approaches

• Acetazolamide, a carbonic anhydrase inhibitor, has been shown to correct metabolic alkalosis in critically ill patients by decreasing the strong ion difference, as demonstrated by 5.
• In a rare case of metabolic alkalosis in a hemodialysis patient, treatment with a proton pump inhibitor was successful in normalizing acid-base homeostasis, as reported by 6.
• These studies suggest that a tailored approach to managing acid-base disturbances in dialysis patients is crucial, taking into account the individual patient's needs and underlying conditions.

Key Considerations

• Regular monitoring of acid-base parameters, including pH, PCO2, and bicarbonate levels, is essential in managing mixed acidosis in dialysis patients.
• Adjusting dialysate bicarbonate concentration and considering the use of medications like acetazolamide or proton pump inhibitors may be necessary to correct acid-base imbalances.
• A comprehensive understanding of the underlying causes of acid-base disturbances in dialysis patients is critical for developing effective management strategies, as highlighted by the studies cited above 2, 3, 4, 5, 6.