There are people who experience this on a day to day basis, either when they run or when they decide to climb up the stairs. Physiologically as we breathe we take in air, that travels the trachea, goes to the alveoli in the lungs through the bronchi. From where it gives in oxygen to the system and gives out carbon dioxide. The oxygen is used by the system for metabolic activity.
Breathlessness is lack of oxygen and lack of oxygen of few seconds can damage the brain, irreversibly.
Mild difficulty in breathing is not really a cause of concern, but breathlessness that comes on suddenly and unexpectedly or that gets worse with time is actually a warning sign of a medical condition and is termed as dyspnoea. Some causes for breathlessness could be problem with lung or airways, like choking, or something is stuck in the throat. This is quite easily handled able. Then there are conditions like Asthma that need medical attention. Breathlessness that comes and goes or it is accompanied with wheezing it is a red flag for asthma. Then there is pulmonary embolism where arteries of the lungs are blocked by blood clots, fat cells or tumour cells. This could manifest with chest pain attached. There are times when low grade fever is present too. Then there is chronic obstructive pulmonary disease that is better known as COPD, the lungs are partially blocked by mucus here. Persistent gradually increasing breathlessness that worsens with even slightest activity, difficulty in catching your breath, wheezing, cough with or without mucus, fatigue are all symptoms of COPD. Pneumonia the lung infection caused by streptococcus pneumonia. Here the breathlessness is accompanied by chest pain on breathing in, fever, cough and sputum production. –
Disorders like angina, heart attack, arrhythmia congenital heart diseases can all cause Breathlessness Due To Cardiac Compromise. These symptoms show up incidentally. Symptom is caused the decreased ability of the heart of fill and empty. This causes an increased pressure of blood around the lungs. The breathlessness is more here when the person is lying down. Symptoms include wakefulness at night, with shortness of breath, cough at night or when lying down, breathlessness with activity swelling of ankles or legs, unusual fatigue with activity and fluid weight gain.
Anxiety could causes breathlessness too. This is due to hyperventilation or over breathing. This happens when our body goes into fight or flight mode. The rapidity in oxygen intake and letting go of carbon dioxide sends the body feedback system the message of inadequacy, this causes hyperventilation.
Allergies and dust in the environment can also cause breathlessness. This is the response of the immune system to threat. This happens because the allergens block the airway.
Obesity, results in decreased function of the respiratory muscles because the muscles are stressed. Moreover the obesity changes the signals from the brain regarding the patterns of breathing.
Rapid spreading of cancer cells puts pressure on the airways causing narrowing of the of the airway and it becomes difficult for the air to pass through, resulting in breathlessness. Cancer patients tend to find this breathlessness, frightening, disabling and restricting. If the cancer is in either the ovary or liver it tends to build up fluid in the abdomen, and pushes against the diaphragm causing breathlessness.
Then there are the man made interventions like surgery, chemotherapy, radiotherapy, can cause breathlessness as a collateral damage.
In all, being breathless though sounds great in a thriller or a romantic novel in every day biology it is worrying.