Side by side
Chronic Bronchitis
An airway problem. Too much mucus clogs the tubes. You get a long-lasting wet cough, low O₂, and high CO₂. Those last two are hypoxemia and hypercapnia.
Emphysema
An air-sac problem. The walls of the alveoli are destroyed and the springy elastic recoil is lost. Air gets trapped, so the patient cannot fully breathe out. That gives a barrel chest and a long, slow exhale.
Oxygen is a drug here: in advanced COPD, CO₂ is often high all the time. Too much oxygen can push the CO₂ even higher, mostly through V/Q mismatch and the Haldane effect, with only a small drop in the drive to breathe. So titrate oxygen to the ordered target, usually an SpO₂ of 88 to 92 percent. Never withhold oxygen from a patient who needs it. Watch for growing drowsiness or confusion.