How to manage metabolic acidosis with low Total Carbon Dioxide (TCO2)?

From the Guidelines

To manage metabolic acidosis with low Total Carbon Dioxide (TCO2), the primary goal is to correct the serum bicarbonate level to 22 mmol/L, especially in patients with a GFR of 30 ml/min per 1.73 m2, as recommended by the renal physicians association clinical practice guideline 1. When managing metabolic acidosis with low TCO2, it is crucial to identify and treat the underlying cause while providing supportive care.

• For patients with mild to moderate acidosis, oral sodium bicarbonate can be administered to help raise the serum bicarbonate levels.
• In cases of severe acidosis or when oral administration is not feasible, intravenous sodium bicarbonate may be considered, with the dose calculated based on the patient's weight and the desired increase in TCO2.
• Additionally, fluid resuscitation with normal saline is essential for correcting volume depletion, and electrolyte imbalances, particularly potassium, must be addressed to prevent worsening hypokalemia during acidosis correction.
• The treatment approach should also include targeted interventions based on the specific cause of the metabolic acidosis, such as insulin and fluids for diabetic ketoacidosis, or dialysis for renal failure, as supported by clinical guidelines like those from the renal physicians association 1.
• Continuous monitoring of the patient's vital signs, electrolytes, and acid-base status is vital during the treatment process to ensure that the correction of metabolic acidosis is achieved safely and effectively, avoiding complications such as paradoxical CNS acidosis, hypokalemia, and fluid overload.

From the FDA Drug Label

In less urgent forms of metabolic acidosis, Sodium Bicarbonate Injection, USP may be added to other intravenous fluids The amount of bicarbonate to be given to older children and adults over a four-to-eight-hour period is approximately 2 to 5 mEq/kg of body weight - depending upon the severity of the acidosis as judged by the lowering of total CO2 content, blood pH and clinical condition of the patient In general, it is unwise to attempt full correction of a low total CO2 content during the first 24 hours of therapy, since this may be accompanied by an unrecognized alkalosis because of a delay in the readjustment of ventilation to normal Values for total CO2 which are brought to normal or above normal within the first day of therapy are very likely to be associated with grossly alkaline values for blood pH, with ensuing undesired side effects.

To manage metabolic acidosis with low Total Carbon Dioxide (TCO2) of 22, sodium bicarbonate (IV) can be administered. The dose is approximately 2 to 5 mEq/kg of body weight over a period of 4 to 8 hours. It is essential to monitor the patient's response and adjust the therapy accordingly. Full correction of the low total CO2 content should not be attempted during the first 24 hours of therapy to avoid unrecognized alkalosis 2.

From the Research

Managing Metabolic Acidosis with Low Total Carbon Dioxide (TCO2)

• Metabolic acidosis is characterized by a primary reduction in serum bicarbonate (HCO(3)(-)) concentration, and a reduction in blood pH 3.
• The calculation of the serum anion gap aids diagnosis by classifying the disorders into categories of normal (hyperchloremic) anion gap or elevated anion gap 4, 3.
• Acute forms of metabolic acidosis most frequently result from the overproduction of organic acids such as ketoacids or lactic acid, while chronic metabolic acidosis often reflects bicarbonate wasting and/or impaired renal acidification 3.

Diagnosis and Treatment

• The appropriate treatment of acute metabolic acidosis, in particular organic form of acidosis such as lactic acidosis, has been very controversial 5.
• Bicarbonate therapy may be considered in patients with severe metabolic acidosis, but its utility remains controversial 6.
• The amount of bicarbonate given should be what is calculated to bring the pH up to 7.2, and intervention should be restrained unless the clinical situation clearly suggests benefit 6.
• The recognition of hypobicarbonatemia is dependent on a reliable assay for total carbon dioxide (TCO2), and differences in bicarbonate assays may affect the diagnosis and treatment of metabolic acidosis 7.

Considerations for Low TCO2

• A low TCO2 level may indicate metabolic acidosis, and the underlying cause should be identified and treated accordingly 4, 3.
• The treatment of metabolic acidosis with low TCO2 should be individualized, and may involve bicarbonate replacement or other therapies aimed at addressing the underlying cause 6, 3.