Respiratory failure is a common consequence of chronic obstructive pulmonary disease (COPD). A concurrent metabolic alkalosis may worsen the respiratory failure, as a higher pH in blood (and thus in cerebrospinal fluid) results in a weaker respiratory drive. Use of diuretics is the most common cause of metabolic alkalosis.

When a patient with an acute exacerbation of a respiratory failure is also alkalotic, there are (at least theoretical) reasons to lower the pH in order to increase the respiratory drive. Among other alternatives, the drug acetazolamide can be used for this purpose.

In some hospitals there is a tradition for the use of acetazolamide on this indication, but any evidence for the effect of such a treatment is rather weak.

Thus, the aim of this trial is to evaluate the effect of acetazolamide as an adjuvant treatment for hospitalized patients with acute exacerbation of respiratory failure in combination with metabolic alkalosis.

Inclusion Criteria:

• Arterial pO2 8 kPa or lower, and arterial pCO2 7 kPa or higher.
• Base Excess 8 mmmol/l or higher.
• Written informed consent

Exclusion Criteria:

• Acetazolamide treatment regarded as obviously indicated or obviously contraindicated
• Already using acetazolamide
• Moribund patient
• Unable to give fully informed consent
• Allergy towards the tablet content or unable to swallow the tablets
• Pregnant or breast-feeding