From the Guidelines
Severe metabolic acidosis can lead to death through multiple mechanisms, including cerebral edema, hypoxemia, and cardiac arrest.
Mechanism of Death
The mechanism of death in a patient with severe metabolic acidosis is complex and multifactorial.
- Cerebral edema: It is a rare but frequently fatal complication of diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS), occurring in 0.7–1.0% of children with DKA 1. Cerebral edema is characterized by a deterioration in the level of consciousness, with lethargy, decrease in arousal, and can progress to seizures, incontinence, pupillary changes, bradycardia, and respiratory arrest.
- Hypoxemia: It may complicate the treatment of DKA, attributed to a reduction in colloid osmotic pressure that results in increased lung water content and decreased lung compliance 1.
- Cardiac arrest: Severe metabolic acidosis can lead to cardiac arrest, which is often precipitated by hypoxemia, hypokalemia, or other electrolyte imbalances.
Clinical Presentation
The clinical presentation of severe metabolic acidosis can vary, but common symptoms include:
- Lethargy and behavioral changes: These are often the first symptoms to appear, and can progress rapidly to more severe neurological deterioration 1.
- Headache: This is a common symptom of cerebral edema, which can occur in patients with severe metabolic acidosis 1.
- Respiratory distress: Patients with severe metabolic acidosis may experience respiratory distress, including hypoxemia and pulmonary edema 1.
Management
The management of severe metabolic acidosis involves prompt correction of the underlying cause, as well as supportive care to prevent complications.
- Fluid replacement: Gradual replacement of sodium and water deficits is essential to prevent cerebral edema 1.
- Insulin therapy: Insulin therapy is critical in the management of DKA and HHS, but must be balanced to prevent hypoglycemia and hypokalemia 1.
- Electrolyte replacement: Electrolyte replacement, particularly potassium, is essential to prevent hypokalemia and cardiac arrhythmias 1.
From the Research
Mechanism of Death in Severe Metabolic Acidosis
The mechanism of death in a patient with severe metabolic acidosis can be attributed to several factors, including:
- Respiratory failure due to diaphragmatic failure, as evidenced by peripheral respiratory (muscle) arrests in experimental septic shock 2
- Cardiac arrest, as acidosis can lower the threshold for ventricular fibrillation and sudden cardiac arrest 2
- Secondary organ failure, including renal failure, leading to further complications 2, 3, 4
- Impaired hemodynamic status, setting the stage for true medical emergencies 3
Pathophysiology of Metabolic Acidosis
Metabolic acidosis can occur as a result of either the accumulation of endogenous acids that consumes bicarbonate (high anion gap metabolic acidosis) or loss of bicarbonate from the gastrointestinal tract or the kidney (hyperchloremic or normal anion gap metabolic acidosis) 4, 5
- High anion gap metabolic acidosis can be caused by lactic acidosis, ketoacidosis, renal failure, and intoxication with certain substances 4, 6
- Hyperchloremic metabolic acidosis can be caused by gastrointestinal bicarbonate loss, renal tubular acidosis, and administration of acids 4
Clinical Consequences
Severe metabolic acidosis can have severe clinical consequences, including death, and requires prompt diagnosis and treatment 2, 6
- The therapeutic approach should be aimed at early correction of concurrent clinical problems, such as fluids and hemodynamic optimization in case of shock, mechanical ventilation in case of concomitant respiratory failure, and hemodialysis for acute intoxications 3