A 47-year-old man was admitted to the ICU with acute hypercapnic respiratory failure caused by a severe asthma attack. He had a history of asthma, atrial septal defect, chronic heart failure, and atrial fibrillation. He underwent surgical closure of the atrial septal defect at 7 years of age and was asymptomatic until 38 years of age when he developed congestive heart failure because of structural cardiac abnormalities, including left ventricular systolic dysfunction, biatrial enlargement, and mild mitral and tricuspid regurgitation. After ICU admission, he received ventilator management for asthma, IV prednisone, beta-2 agonist via inhalation, and ceftriaxone. Enteral feeding was provided since the day of admission. Hypercapnia gradually improved over 3 days. He remained alert and could communicate through writing during ventilator management until the third day in the ICU. Enteral feeding was titrated up to 32 kcal/kg/d with 1.6 g/kg/d of protein. Despite the recovery from the initial respiratory failure, he became inactive and lethargic on the fourth day in the ICU. ICU-acquired delirium was suspected, and administration of sedatives and analgesics was discontinued. On the following day, he was unresponsive to stimuli.