<prompt> Most common cause of hypercapnic respiratory failure: March 2011,Parch 2013 a, b, hAcute asthmaAspergillosisCOPDPneumothorax  <response>: Ans. C: COPD Causes of type II hypercapnic respiratory failure: Chronic causes: COPD, sleep apnea, kyphscoliosis, myopathies muscular dystrophies, ankylosing spondylitis; Acute causes: Acute severe asthma NOT acute asthma, acute exacerbation of COPD, upper airway obstruction, narcotic drugs etc. Type II respiratory failure: Reduced PaO2 Increased PaCO2 Normal PA-aO2 Hypoxemia with increased PaCO2 Type I respiratory failure: Reduced PaO2 Normal decreased PaCO2 INcreased PA-aO2 Hypoxemia with decreased PaCO2 