Question
The most common acid-base disturbance in critically ill patients is:
| A. | Chronic respiratory acidosis |
| B. |
Chronic respiratory alkalosis |
| C. |
Chronic metabolic acidosis |
| D. |
Chronic metabolic alkalosis |
Show Answer
|
Correct Answer » B Explanation |
 |
Respiratory alkalosis is the most common simple acid–base disorder in critically ill patients. It results from alveolar hyperventilation, commonly seen in:
- Sepsis
- Hypoxemia
- Pain
- Anxiety
- Fever
- Mechanical ventilation
Hyperventilation causes excessive elimination of carbon dioxide (CO₂), leading to decreased PaCO₂ and respiratory alkalosis.
Why Other Options Are Incorrect
A. Respiratory Acidosis
- Caused by hypoventilation (e.g., COPD exacerbation, neuromuscular disease, CNS depression).
- Less common than respiratory alkalosis in critically ill patients.
C. Metabolic Acidosis
- Common in shock, sepsis, diabetic ketoacidosis, and renal failure.
- It is the most common metabolic disturbance at ICU presentation but not the most common simple acid–base disorder.
D. Metabolic Alkalosis
- Common in prolonged ICU stay due to vomiting, diuretics, nasogastric suction, and alkali therapy.
- It is not the most common initial simple acid–base disorder.