Paroxysmal nocturnal dyspnea (PND) is a condition that triggers sudden shortness of breath during sleep. This difficulty in breathing can cause a person to wake up gasping for air.
It usually occurs several hours after a person falls asleep and improves when they sit upright.
It can be a distressing experience, and a person may feel highly anxious after a PND episode.
In this article, we discuss what PND is, its symptoms, causes, and risk factors. We also look at the treatment options and when a person should seek help.
Breaking down this condition’s name can help people understand its meaning:
- Paroxysmal refers to symptoms that come on and pass quickly.
- Nocturnal refers to occurring at nighttime or during sleep.
- Dyspnea refers to difficult or uncomfortable breathing.
A person can use PND to describe any condition that causes breathing difficulties during sleep. However, cardiologists also use the term when a person experiences this issue at night, specifically due to heart failure.
PND and orthopnea both cause breathing problems while a person is lying down. However, there are some key differences.
PND causes difficulty breathing during sleep, causing people to wake up due to shortness of breath.
One 2011 article notes this often happens 1–2 hours after they fall asleep. However, symptoms improve when a person wakes and sits up.
Orthopnea occurs when a person feels breathless when they are lying down.
The same article states that, unlike PND, orthopnea symptoms can occur when a person is awake. Similarly to PND, symptoms can improve when a person sits or stands.
Orthopnea occurs due to congestion in the lungs when a person lies down. This can result from a redistribution of blood when the body becomes horizontal.
This does not trigger any symptoms in most people. However, in those with orthopnea, the left ventricle of the heart cannot pump out the additional volume of blood. This increases pressure in the pulmonary veins, causing fluid to leak into the lungs, resulting in shortness of breath.
Symptoms of PND include:
- waking up gasping for air after falling asleep
- coughing after waking up
A person may also experience symptoms of a more serious condition that causes their PND.
A 2016 article notes that approximately 90% of all dyspnea cases are due to a lung or heart condition.
Healthcare professionals associate PND, alongside orthopnea, as specific symptoms of heart failure.
Heart failure occurs when the heart struggles to pump blood throughout the body.
When the heart stops working correctly, the body produces renin, an enzyme that triggers fluid and sodium retention. This leads to swelling if the heart is unable to handle the extra fluid. It can then build up in the lungs, which causes shortness of breath.
Some heart conditions that may cause PND include:
- acute decompensated heart failure, a sudden worsening of heart failure symptoms
- myocardial ischemia, a form of heart disease
Some respiratory conditions that trigger PND include:
- asthma, a chronic condition that affects a person’s lungs
- chronic obstructive pulmonary disease, which refers to a variety of lung conditions that cause breathing difficulties
- pneumonia, an inflammation of the lungs
Other health conditions that may cause PND include:
- psychogenic disorders, which refer to the physical illnesses that occur due to emotional and mental stressors, such as anxiety
- kidney disease
- acid reflux
A person may develop PND if they are at risk of developing heart or lung conditions.
Risk factors for heart failure include:
- a previous heart condition
- high blood pressure
- coronary heart disease
- high cholesterol
- tobacco and alcohol use
- low activity levels
- an unhealthy diet
Risk factors for lung disease include:
- tobacco smoke, including second-hand tobacco smoke
- air pollutants
As PND can occur due to respiratory and cardiac conditions, a healthcare professional will want to diagnose the underlying cause.
Diagnostic tests may include a combination of:
- physical exams, including blood pressure tests, weight measurements, and listening to a person’s heart and lungs
- blood tests to analyze the levels of sodium, potassium, albumin, creatinine, and certain biomarkers in the blood
- chest X-rays to look for an enlargement of the heart, or if there is congestion in the lungs
- electrocardiograms that record the rhythm of a person’s heartbeat, the frequency of beats, and the heart’s electrical activity
- echocardiography to assess the heart’s structure and how well it is pumping
- exercise stress tests that measure how a person’s heart responds to being put under pressure through exercise
- radionuclide ventriculography or multiple-gated acquisition scanning
- cardiac catheterization
- magnetic resonance imaging
Treatments for PND depend on the cause.
People can treat heart failure with lifestyle changes, such as:
- stopping smoking
- maintaining a moderate weight
- eating a healthful diet
Medications may include:
- angiotensin-converting enzyme inhibitors
- angiotensin II receptor blockers
- angiotensin-receptor neprilysin inhibitors
- If channel blockers
Surgery or special implanted devices can also treat heart failure.
If PND occurs due to a lung condition, a healthcare professional may prescribe the following:
- asthma medication
- using a continuous positive airway pressure machine to make breathing easier during sleep
A person can also use additional pillows to elevate their chest while they sleep.
PND is a serious condition. A person who suspects they may have symptoms should see a doctor as soon as possible for diagnosis and treatment.
If a person shows signs of heart failure, they should seek emergency medical care. PND may indicate that a person is living with advanced heart failure.
If a person experiences PND and their breathing does not return to normal for a long time, they should seek urgent medical help.
PND is a condition that causes a person to experience shortness of breath while they sleep. It can be a symptom of a severe illness, such as heart failure.
There are many treatments available for these underlying causes. People may be able to control their PND symptoms by treating the condition that triggers it.