From the Research
The patient is experiencing metabolic alkalosis with respiratory compensation, as evidenced by the elevated pH, increased bicarbonate (HCO3-), and elevated PCO2. This condition is likely caused by the loss of gastric acid through vomiting, leading to a relative excess of bicarbonate in the bloodstream 1. The elevated PCO2 represents a compensatory respiratory response, where the body retains carbon dioxide by decreasing ventilation to partially offset the alkalemia. Dehydration worsens this condition by causing contraction alkalosis and stimulating aldosterone release, which increases renal hydrogen ion secretion and bicarbonate reabsorption. Key points to consider in the diagnosis and management of this condition include:
- Evaluating the patient's volemic status and measuring urinary chloride and plasma levels of renin and aldosterone to identify the underlying cause of metabolic alkalosis 2
- Correcting existing depletions and preventing further losses, such as replenishing potassium and chloride stores 2
- Using isotonic saline (0.9% NaCl) for rehydration to correct volume depletion and dilute bicarbonate 3
- Considering the use of antiemetics, such as ondansetron, to control vomiting and acetazolamide to enhance bicarbonate excretion in severe cases, while being cautious of potential side effects 3. Given the patient's presentation, the most appropriate diagnosis is metabolic alkalosis with respiratory compensation, and treatment should focus on addressing the underlying cause of vomiting, rehydrating with isotonic saline, and replacing potassium as needed.