Metabolic Acidosis

A physiologic state of excess acid accumulation and deficient base bicarbonate, metabolic acidosis is produced by an underlying pathologic disorder. Symptoms result from the body's attempts to correct the acidotic condition through compensatory mechanisms in the lungs, kidneys, and cells.

Metabolic acidosis is more prevalent among children, who are vulnerable to acid-base imbalance because their metabolic rates are faster and their ratios of water to total-body weight are lower. Severe or untreated metabolic acidosis can be fatal.

Causes

Metabolic acidosis usually results from excessive burning offats in the absence of usable carbohydrates. This can be caused by diabetic ketoacidosis, chronic alcoholism, malnutrition, or a low-carbohydrate, high-fat diet-all of which produce more keto acids than the metabolic process can handle.
Other causes include:

• anaerobic carbohydrate metabolism: a decrease in tissue oxygenation or perfusion, as occurs with pump failure after myocardial infarction, or when pulmonary or hepatic disease, shock, or anemia forces a shift from aerobic to anaerobic metabolism, causing a corresponding rise in the lactic acid level
• renal insufficiency and failure (renal acidosis): underexcretion of metabolized acids or the inability to conserve base
• diarrhea and intestinal malabsorption: loss of sodium bicarbonate from the intestines, causing the bicarbonate buffer system to shift to the acidic side. For example, ureteroenterostomy and Crohn's disease can also induce meta­bolic acidosis.

Signs and symptoms

In mild acidosis, symptoms of the underlying disease may obscure any direct clinical evidence. Metabolic acidosis typically begins with headache and lethargy, progressing to drowsiness, central nervous system depression, Kussmaul's respirations (as the lungs attempt to compensate by "blowing off" carbon dioxide), stupor and, if the condition is severe and goes untreated, coma and death.

Associated Gl distress usually produces anorexia, nausea, vomiting, and diarrhea and may lead to dehydration. Diabetic patients with symptoms of metabolic acidosis may also have breath that smells fruity. The patient may lose consciousness or become disoriented. Severe cases can produce coma and death .

Diagnosis

Blood tests to diagnose metabolic acidosis may include:

• An arterial blood gas to assess the severity of the metabolic acidosis
• A metabolic panel to reveal the cause and severity of the metabolic acidosis
• A complete blood count (CBC) to assess possible causes of metabolic acidosis

Treatment

In metabolic acidosis, treatment consists of administration of sodium bicarbonate I. V. for severe cases, evaluation and correction of electrolyte imbalances and, ultimately, correction of the underlying cause.

If the patient is diabetic, insulin may be administered. Drugs to regulate blood pressure or heart rate, to prevent seizures, or to control nausea and vomiting might be given. Vital signs like pulse, respiration, blood pressure, and body temperature will be monitored. The underlying cause of the metabolic acidosis must also be diagnosed and corrected.

Prevention

Diabetic patients need to routinely test their urine for sugar and acetone, strictly follow their appropriate diet, and take any medications or insulin to prevent metabolic acidosis. Patients receiving tube feedings or intravenous feedings must be monitored to prevent dehydration or the accumulation of ketones or lactic acid