Respiratory failure can be a very acute condition, or it may evolve gradually due to chronic diseases. The basic precursors of respiratory failure generally include hypoxia or hypercapnia. In the early stages of hypoxia, patients may experience excitement or irritability, characterized by rapid breathing and possibly sweating due to the effort of breathing. Symptoms include accelerated breathing and hypoxia; the patient’s lips may also turn blue. If the level of carbon dioxide increases, once past the initial period of excitement and as the hypoxia worsens, the person may become listless. Gradually, their consciousness may become unclear, manifesting as drowsiness or possibly even coma.