Problem: Mr. Blue is a patient with COPD. He is combative and disoriented to time and place. He has diffuse bilateral rhonchi and wheezes. His vital signs are: BP 170/90, HR 135, RR 55, Temp 101F, Wt. 80kgs. ABGs on room air: pH 7.20, PaO2 50, PaCO2 68, HCO3 30. What is the most likely cause of his combativeness and disorientation?