History
The etiology of a metabolic acidosis is often apparent from the patient’s history and physical examination. The following factors are assessed in a complete investigation of the patient's history:
-
Anorexia, nausea, vomiting, or diarrhea - In pediatric patients, diarrhea is the most common cause of a metabolic acidosis
-
Metabolic acidosis associated with seizures, a depressed sensorium, or both in a neonate - This warrants consideration of an inborn error of metabolism, or neonatal sepsis
-
History of depressed mental status, lethargy, and poor feeding in a neonate - Left-sided, obstructive cardiac lesions should be considered (eg, aortic coarctation or hypoplastic left heart syndrome)
-
Failure to thrive suggestive of chronic metabolic acidosis - This can be seen in renal insufficiency or RTA
-
New onset of polyuria, polydipsia, and weight loss - This could signify undiagnosed diabetes mellitus and diabetic ketoacidosis in a child
-
Possible ingestion of a toxin or other form of intoxication - Inquire as to what medications are in the home; suspect a poisoning in a healthy child who quickly develops a metabolic acidosis; possible agents are ethanol, ethylene glycol, salicylates, and methanol
-
History of trauma, hives, or fever
-
History of states associated with a lactic acidosis secondary to shock from hypovolemia, sepsis, cardiac failure, anaphylaxis, or spinal shock
-
Chronic medical or surgical issue - Examples to be concerned with include chronic renal failure, presence of a ureterosigmoidostomy, or diabetes mellitus
Physical Examination
Clinical findings generally depend on the etiology and severity of the metabolic acidosis.
Hyperventilation or Kussmaul breathing may often be the first sign of a metabolic acidosis in a child. Breath sounds are often clear to auscultation (“quiet tachypnea”).
Patients with metabolic acidosis secondary to shock may have signs reflective of single- or multiple-organ dysfunction, as follows:
-
CNS manifestations may include lethargy, coma, and seizures
-
Respiratory manifestations may include tachypnea, respiratory distress, and hypoxemia
-
Cardiovascular signs may include poor perfusion, weak pulses, tachycardia, hypotension, murmurs, or a gallop
-
Nonspecific abdominal symptoms and signs may be present such as nausea, pain, vomiting, and altered appetite
-
Signs of dehydration may include tachycardia, dry mucous membranes, and delayed capillary refill
-
Patients with diabetic ketoacidosis may present with fruity odor to their breath
-
Approach for evaluating metabolic acidosis.
