Dyspnea, or shortness of breath, is a subjective sensation indicating potential disorders due to inadequate ventilation or insufficient oxygen levels in the blood. It arises from a mismatch in signaling between the brain's assessment of respiratory needs and actual ventilation performance, involving physiological and psychological factors. Various causes include cardiac conditions, pulmonary diseases, and non-cardiac/non-pulmonary factors, with management strategies focusing on stabilizing the patient and addressing underlying issues.