Metabolic alkalosis(MA) is common metabolic disorder in ICU setting. MA could be cause of weaning failure or delay by depression of respiratory center. The purpose of this study is to evaluate that correction of MA by administration of acetazolamide facilitates weaning of mechanical ventilation.

Inclusion Criteria:

• Patients on mechanical ventilation for at least 24 hours with an assisted mode and passed acute resuscitation and considered for weaning. (Definition of Weaning point:

  1. Oxygenation

     • FiO2 ≤ 0.4 & PaO2 ≥ 60 mmHg

       • O2 index (PaO2/FiO2) ≥ 150

         • SaO2 > 90%

           • PEEP ≤ 5 cmH2O

             • MN ≤ 15 L/min

  2. Vital sign

     • Stable BP: MAP ≥ 60 mmHg ((i.e., no epinephrine or norepinephrine <0.2μg/kg/min, or equivalent dose vasopressin or phenylephrine)

       • HR ≤ 140bpm

         • 35 ≤ BT ≤ 38 ℃

           • RR ≤ 35/min

  3. Clinical status

     • resolution of acute disease process

       • no newly developed pulmonary infiltration

         • Ramsay sedation score 2~4

           • Hb > 7, pH > 7.30, normal electrolyte

             • no active bleeding, no IICP, no bronchospasm, no CAD

               • no rescure or specific treatment (NO, prone, OP plan)

• ABGA : pH ≥ 7.43 and HCO3- ≥ 26mEq/L

Exclusion Criteria:

• Permanent ventilator dependency due to brainstem disease, diffuse cerebral disease, severe respiratory or neuromuscular disease
• Active bleeding, IICP, unstable coronary artery disease, bronchospasm, and rescue treatment (inhaled NO, prone), pre-op condition
• Contraindication to acetazolamide: renal insufficiency (creatinine clearance <20 ml/min and/or renal replacement therapy), intolerance or allergy to acetazolamide or sulfonamides, hyperchloremic metabolic acidosis, hyponatremia (Na<130), hypokalemia (K<3.5), adrenal insufficiency.
• Diaphragm dysfunction : as diagnosed by fluoroscopy, nerve conduction velocity, USG, or overt paradoxical motion of the abdomen