Definition Dyspnea is defined as an awareness of difficulty in breathing It is therefore a symptom, usually described by the patient as shortness of breath, whether the sensation is due to actual difficulty in breathing or is essentially an awareness of hyperventilation. If the symptom becomes striking, it always companies with dilatation of nares cyanosis, use of accessory muscles of respiration and abnormalities of respiratory rate, depth or rhythmDefinition: Dyspnea is defined as an awareness of difficulty in breathing It is therefore a symptom, usually described by the patient as “shortness of breath,” whether the sensation is due to actual difficulty in breathing or is essentially an awareness of hyperventilation. If the symptom becomes striking, it always companies with dilatation of nares, cyanosis, use of accessory muscles of respiration and abnormalities of respiratory rate, depth or rhythm