Characterized by a feeling of general discomfort due to insufficient oxygenation of blood and tissues. Patients describe their feelings associated with shortness of breath, in different ways - "there is not enough air", "the feeling is squeezed in the chest, behind the sternum, in the throat", "fatigue in the chest," "I can not breathe in full," "I snap the air open my mouth , "I breathe like a fish", etc.