So what are the symptoms of respiratory failure?

Respiratory failure: There are a couple causes of respiratory failure that can manifest differently. Respiratory failure from not getting enough oxygen usually causes people to breathe fast and deep and feel extrememly shrt of breath. Respiratory failure from too much carbon dioxide usually makes people sleepy and unresponsive. Respiratory failure from an obstructed airway makes it impossible to talk.

Lung failure...: Respiratory failure occurs when the lungs are unable to function normally. There are many etiologies that can lead to respiratory failure. It is characterized by a high carbon dioxide level and a low oxygen level in arterial blood. Symptoms include shortness of breath, cyanosis, mental status change and other symptoms specific to the underlying cause of the respiratory failure.

Difficulty breathing: Strictly speaking respiratory failure is when there is 1) failure of the drive to breathe 2)inadequate air flow 3)inadequate transport of oxygen 4) failure of the chest wall and diaphragm 5) lung disease which limits the performance of normal lung functions. Sometimes artificial support with mechanical ventilation can temporarily provide time for the lung to repair.