Nocturnal Paroxysmal Dyspnea: Symptoms, Causes and Treatment

Definition: is commonly referred to as cardiac asthma.

It is characterized by the sudden and severe lack of air at night that can wake a person can cause coughing and wheezing.

Paroxysmal nocturnal dyspnea is a sign of congestive heart failure and often occurs one to two hours after the person with heart failure falls asleep.

Specifically, dyspnea “refers to the sensation of difficult or uncomfortable breathing,” according to the National Biotechnology Information Center.

However, dyspnea is not the same as hyperventilation, which consists of short, rapid breaths and an inability to breathe. Dyspnea can also be associated with effort.

What are the signs and symptoms?

Because the left side of the heart (left atrium and left ventricle) does not pump blood properly, a reserve of fluid is produced in the lungs.

Water leaves the tiny capillary blood vessels in the lungs. This hinders the absorption of oxygen and creates shortness of breath.


Paroxysmal nocturnal dyspnea is caused by an accumulation of fluid in the lungs that enter the alveoli (air pockets) while a person sleeps. The alveoli are responsible for exchanging oxygen and carbon dioxide from the blood.

During the day, the fluid is retained in the legs. At night, while asleep, the body reabsorbs this fluid resulting in an increase in total blood volume and blood pressure that leads to pulmonary hypertension or edema. Many patients naturally counteract these symptoms without noticing the congestive heart failure nature of these symptoms by sleeping on several pillows or sleeping while sitting.

One explanation for the onset of symptoms is that the left ventricle is starting to fail and cannot keep up with the performance of a perfectly healthy right ventricle. Other theories, according to NCBI, include “decreased response capacity of the respiratory center in the brain and decreased adrenergic activity (adrenaline) in the myocardium (heart muscles) during sleep.”

Common causes of paroxysmal nocturnal dyspnea

Paroxysmal nocturnal dyspnea and orthopnea have similar causes. One of the causes of orthopnea is pulmonary congestion (excessive or abnormal accumulation of blood in the lungs) when a patient lies down and blood moves from the lower part of the body to the lungs.

In normal individuals, this has little effect, but in patients with heart failure, the diseased left side of the heart can not pump the additional volume. Therefore, the blood recedes into the vessels of the lungs, causing shortness of breath.

In nocturnal paroxysmal dyspnea, increasing fluid enters the lungs during sleep and fills tiny air-filled sacs where oxygen is absorbed from the atmosphere.

The failed left side of the heart is suddenly unable to match the output of a normal functioning right side, resulting in congestion in the lungs, coughing and wheezing, and sometimes the production of sputum (mucus and other matter can be bloody). ).

We do not know why paroxysmal nocturnal dyspnea occurs so suddenly in patients with left heart failure.

In addition, pulmonary circulation in patients with congestive heart failure may already be overloaded. This condition can be worsened by fluid overload, excess fluid that accumulates in the lower part of the body during the day and moves to the lungs when the patient lies down. Pulmonary congestion decreases when the patient lifts the upper part of the body.

Other causes:

  • Chronic Obstructive Pulmonary Disease (COPD): a group of lung conditions, including chronic bronchitis and emphysema, that affect the lungs’ ability to function normally.
  • Cor Pulmonale: “An acute strain or hypertrophy [abnormal enlargement] resulting from disease of the lungs or other blood vessels.”
  • Heart failure.
  • Hypertensive heart disease.
  • Obesity (which aggravates other conditions).
  • Panic disorders
  • Sleep apnea.
  • Snore.

Depending on the symptoms and pre-existing conditions, chest x-rays, ECG (echocardiogram), or pulmonary function tests can determine the exact reason for symptoms.

If you have unexplained shortness of breath at any time, make an appointment with a doctor.


The treatment depends on the exact cause of the episodes. Doctors generally recommend weight reduction for obese patients, and supplemental oxygen can alleviate the symptoms. If the attacks are due to heart failure, measures are taken to treat fluid overload.

Because a diet rich in salt can contribute to fluid overload, doctors generally recommend that people who experience breathing difficulties such as paroxysmal nocturnal dyspnea limit the amount of salt in their diets.

In addition to not adding salt to the table, following a low-sodium diet involves avoiding most processed foods (including frozen and canned foods and most fast food and take-away foods).

Eating homemade meals made with herbs and spices instead of salt is one of the most effective ways to get rid of excess fluid.

In addition to recommending a low-sodium diet, doctors often prescribe diuretics medications to relieve fluid overload symptoms. Although these methods work for a while, they often become ineffective.

When this happens, people with fluid overload are usually admitted to the hospital and treated with intravenous medications such as diuretics, vasodilators, and inotropic drugs.

Another procedure, known as ultrafiltration, is available to relieve fluid overload. In ultrafiltration therapy, the person’s blood is passed through a filter that removes excess fluid. Next, the filtered blood (minus the extra liquid) is returned to the patient.