Metabolic Acidosis in Emergency Medicine Clinical Presentation

Updated: Jun 20, 2016
  • Author: Antonia Quinn, DO; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Presentation

History

Metabolic acidosis can result in a variety of nonspecific changes in several organ systems, including, but not limited to, neurologic, cardiovascular, pulmonary, gastrointestinal, and musculoskeletal dysfunction. Symptoms are often specific to and a result of the underlying etiology of the metabolic acidosis.

Head, eyes, ears, nose, throat (HEENT) findings include the following:

  • Tinnitus, blurred vision, and vertigo can occur with salicylate poisoning.
  • Visual disturbances, dimming, photophobia, scotomata, and frank blindness can be seen in methanol intoxication.

Cardiovascular findings include the following:

  • Palpitations
  • Chest pain

Neurologic findings include the following:

  • Headache
  • Visual changes
  • Mental confusion

Pulmonary findings include subjective dyspnea from the patient's observation of hyperventilation.

GI findings include the following:

  • Nausea and vomiting
  • Abdominal pain
  • Diarrhea
  • Polyphagia

Musculoskeletal findings include the following:

  • Generalized muscle weakness
  • Bone pain
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Physical

Neurologic

Cranial nerve palsies may occur with ethylene glycol intoxication.

Retinal edema may be seen in methanol ingestions.

Lethargy, stupor, and coma may occur in severe metabolic acidosis, particularly when it is associated with a toxic ingestion.

Cardiovascular

Severe acidemia (ie, pH < 7.10) can predispose a patient to potentially fatal ventricular arrhythmias, and it can reduce cardiac contractility and the inotropic response to catecholamines, resulting in hypotension and congestive heart failure.

Pulmonary

Patients with acute metabolic acidosis demonstrate tachypnea and hyperpnea as prominent physical signs.

Kussmaul respiration, an extremely intense respiratory effort, may be present.

Hyperventilation, in the absence of obvious lung disease, should alert the clinician to the possibility of an underlying metabolic acidosis.

Musculoskeletal

Chronic metabolic acidosis (eg, uremia, renal tubular acidosis [RTA]) is associated with substantial bone disease from bone buffering of calcium carbonate.

Long bone malformations in pediatric patients (eg, vitamin D resistant, rickets) and fractures in adult patients are noted.

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Causes

Causes of inability to excrete the dietary H+ load are as follows:

  • Renal failure - Diminished NH 4 + production
  • Hypoaldosteronism - Type 4 RTA
  • Diminished H + secretion - Type 1 (distal) RTA

Causes of increased H+ load include the following:

  • Lactic acidosis - Numerous causes, including circulatory failure, drugs and toxins, and hereditary causes (see Lactic Acidosis) [4]
  • Ketoacidosis - Diabetes, alcoholism, and starvation
  • Ingestions - Salicylates, methanol, ethylene glycol, isoniazid, [5] iron, paraldehyde, sulfur, toluene, ammonium chloride, phenformin/metformin, [6] and hyperalimentation fluids

GI HCO3- loss is caused by the following:

  • Diarrhea
  • Pancreatic, biliary, or intestinal fistulas
  • Ureterosigmoidostomy
  • Cholestyramine

Renal HCO3- loss may be caused by type 2 (proximal) RTA.

Acetazolamide may also be a cause of metabolic acidosis.

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