<prompt> About respiratory failure, the following is false:Type III failure involves post-operative atelectasisType II failure doesnt have fall in paO2 hypoxiaType I failure involves hypoxia paO2Pneumonia usually presents with type I respiratory failure  <response>: Type I or Hypoxemic respiratory failure is characterized by PaO2 60 mm Hg with a normal or low arterial carbon dioxide tension. Causes:- Pneumonia, ARDS, pulmonary embolism, pulmonary edema Type II or Hypercapnic respiratory failure is characterized by a PaCO2 50 mm Hg. May be associated with hypoxemia. Causes:- Drug overdose, neuromuscular disease, chest wall abnormalities, and severe airway disorders eg, asthma and COPD Type III failure involves post-operative atelectasis.Type IV failure is due to decreased blood flow to respiratory muscles. 