A 54 y.o. male patient suffers from dyspnea during mild physical exertion, cough with sputum which is excreted with diffculty. On examination: diffuse cyanosis. Is Barrel-chest. Weakened vesicular breathing with prolonged expiration and dry whistling rales. Ap is 140/80 mm Hg, pulse is 92 bpm, rhythmic. Spirography: vital capacity (vC)/predicted vital capacity- 65%, FEV1/FVC- 50%. Determine the type of respiratory insufficiency (RI).