Dyspnea - Causes and Symptoms

Definition

Dyspnea consists of the sensation of difficult, forced breathing accompanied by subjective suffering. This manifestation arises following an increase in respiratory work or when the respiratory centers located in the brainstem or the receptors located at the level of the upper airways, alveolar and interstitial space, respiratory muscles and chest wall are stimulated.

Dyspnea is felt differently by patients; more commonly, it is described as "breathlessness", "air hunger", "sense of weight on the chest" and "inability to take a deep breath".

Respiratory difficulty may occur suddenly (acute dyspnea) or gradually (as in chronic diseases of various origins). Often, it represents the cardinal symptom of respiratory pathologies (especially pulmonary), but it can also be caused by diseases affecting other districts (eg heart diseases and neuromuscular disorders) and by conditions such as stress or anxiety. Dyspnea can also be of a functional nature (when it is a compensatory phenomenon implemented to overcome an obstacle to regular pulmonary ventilation or to satisfy a body's greater demand for oxygen).

The most frequent causes of dyspnea include asthma, pneumonia, chronic obstructive pulmonary disease (COPD) and myocardial ischemia.

Dyspnea acute

Pulmonary causes

Dyspnea occurs abruptly in pneumothorax, pulmonary embolism and secondary lesions of thoracic trauma and rib fractures.

Acute asthma crises are accompanied by severe wheezing, coughing and a feeling of constriction and chest tightness.

A sudden "breathlessness" may also depend on bronchospasm or airway hyper-responsiveness, aroused by stimulation of the "irritative" receptors of the bronchi after exposure to specific stimuli (eg allergens, upper respiratory tract infections, cold and physical exercise).

The sudden appearance of acute dyspnea in a patient (usually a newborn or a small child) who does not present other constitutional symptoms may indicate inhalation of a foreign body.

The acute onset of a respiratory difficulty may also result from exposure to toxic substances to the airways (eg inhalation of chlorine or hydrogen sulfide).

Subacute dyspnea (within a few hours or days) may appear, instead, in the presence of pneumonia, pulmonary edema and exacerbation of COPD.

Cardiac causes

The most common causes of dyspnea of sudden-onset cardiac origin are ischemia or myocardial infarction and heart failure. An acute respiratory difficulty may also depend on angina or coronary artery disease, pericardial effusion or tamponade, and dysfunction or rupture of a papillary muscle.

Other causes

Acute dyspnoeic crises can be caused by paralysis of the diaphragm. Furthermore, they can accompany anxiety disorders, without any patient having any anatomical-functional respiratory, cardiac or neuromuscular damage.

The causes of dyspnea psychology also include depression and panic attacks.

Chronic dyspnea

Dyspnea is the most common symptom of chronic respiratory diseases, such as bronchitis, COPD, emphysema, asthma, cystic fibrosis, interstitial lung diseases and primitive or metastatic lung tumors. Heart failure is one of the main causes of chronic shortness of breath.

Neurological conditions such as spinal cord injury, Guillain-Barré syndrome, amyotrophic lateral sclerosis, multiple sclerosis and muscular dystrophy can cause varying degrees of respiratory distress. Also the deformities of the thoracic cage, such as kyphoscoliosis, pectus excavatum and ankylosing spondyloarthritis, are able to generate dyspnea.

Other non-pulmonary causes include metabolic disorders, arrhythmias, valvulopathies, anemia and physical deconditioning, in which dyspnea occurs under exertion in patients with a sedentary lifestyle.