Acetazolamide Causes Worsening Acidosis in Uncompensated COPD Exacerbations: Increased Awareness Needed for Patient Safety.

BACKGROUND

Acetazolamide has been studied extensively in post-hypercapnic alkalosis as a tool to facilitate ventilator weaning in chronic obstructive pulmonary disease (COPD). It has also been utilized to facilitate respiratory drive in nonmechanically ventilated patients with COPD. Although this is generally a forgiving intervention, providers must carefully select patients for this medication, as it can cause severe acidosis and deterioration of clinical status in severe COPD cases. The present report describes two cases of patients who developed worsening acidosis and hypercapnia after receiving acetazolamide in acute respiratory failure.

CASE REPORT

Case 1 was a 72-year-old obese male with COPD who was dependent on supplemental oxygen and presented to the emergency department (ED) with acute on chronic hypercapnic respiratory failure. He was given a one-time dose of acetazolamide in the ED for "respiratory failure made worse by severe metabolic alkalosis." His arterial blood gas (ABG) worsened overnight, accompanied by decreased mental status: pH 7.32, paCO 82 mm Hg, paO 50 mm Hg, HCO 41.7 mmol/L, FiO 32% to pH 7.21, paCO 91.7 mm Hg, paO 59 mm Hg, HCO 36.6 mmol/L, and FiO 32%. Case 2 was a 62-year-old male with COPD who was dependent on supplemental oxygen and presented to the ED with acute on chronic hypercapnic respiratory failure. He was given acetazolamide in the ED with similar results: ABG on presentation pH 7.37, paCO 79.3 mm Hg, paO 77.6 mm Hg, HCO 45.5 mmol/L, and FiO 32%. The next morning, ABG was pH 7.29, paCO 79 mm Hg, paO 77 mm Hg, HCO 45.5 mmol/L, and FiO 32%. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Acetazolamide given early in the uncompensated setting can worsen acidosis and potentiate clinical deterioration.