Question

Describe the four major Respiratory and Metabolic Acid-Base abnormalities. What are the most frequent causes of each?

Answer 1

Respiratory acidosis
Reduced CO2 elimination

• Decreased breathing rate (respiratory drive) due to drugs or central nervous system disorders
• Impaired breathing and lung movement (respiratory mechanics) due, for example, to trauma or abnormal presence of air between the lung and the wall of the chest (pneumothorax)
• Respiratory muscle/nerve disease (myasthenia gravis, botulism, amyotrophic lateral sclerosis (ALS), Guillain-Barre syndrome)
• Airway obstruction (food or foreign object)
• Lung disease

Respiratory alkalosis
Increased CO2 elimination

• Hyperventilation due to anxiety, pain, shock
• Drugs, such as early in a overdose of aspirin (salicylates)
• Pneumonia, pulmonary (lung) congestion (due to heart failure), or embolism
• Exercise
• Fever
• Central nervous system tumor, trauma, infection (meningitis, encephalitis)
• Liver failure

Metabolic acidosis
Decreased HCO3-, due to increased acid or loss of bicarbonate

• Alcoholic ketoacidosis
• Diabetic ketoacidosis
• Kidney failure
• Lactic acidosis
• Toxins – late in an overdose of salicylates (aspirin), methanol, ethylene glycol
• Gastrointestinal bicarbonate loss, such as from prolonged diarrhea
• Renal bicarbonate loss

Metabolic alkalosis
Increased HCO3-, due to loss of acid or gain of bicarbonate

• Diuretics
• Prolonged vomiting
• Severe dehydration
• Diseases that cause loss of potassium
• Administration of bicarbonate, ingestion of alkali