Paroxysmal nocturnal dyspnea
Imagine waking up from sleep suddenly gasping for air, coughing, wheezing and feeling like you’re suffocating. Anxious and scared, you might quickly sit up and put your feet on the floor. Sitting or standing up helps you breathe better again. This frightening occurrence is a sign of heart failure and it may sometimes happen to people who haven’t had any previous symptoms of heart trouble.
The scientific term for this is paroxysmal nocturnal dyspnea. Paroxysmal means sudden attacks that recur, nocturnal means occurring at night and dyspnea means difficulty breathing or shortness of breath.
Paroxysmal nocturnal dyspnea is also referred to as cardiac asthma because its signs and symptoms mimic those of an asthma attack. This term is actually misleading since the two conditions are very different. Whileas asthma is a chronic condition caused by the inflammation of the airways, which can lead to breathing difficulties, paroxysmal nocturnal dyspnea is a sign of heart failure.
In many cases, Paroxysmal nocturnal dyspnea can be accompanied by swelling of the feet or ankles. It is caused by congestionin the lungs, perhaps along with accumulation of excess fluid in the lungs, which occurs as a result of left-sided heart failure. Some patients who experience paroxysmal nocturnal dyspnea also experience orthopnea where one experiences breathlessness when lying down which is relieved when several pillows raise the head and upper body. People with paroxysmal nocturnal dyspnea must keep their heads elevated to breathe comfortably. Paroxysmal nocturnal dyspnea is an intense form of orthopnea. It commonly occurs several hours into sleep and it’s relieved by sitting upright, but not as quickly as is orthopnea.
Paroxysmal nocturnal dyspnea refers to attacks of severe shortness of breath and coughing that generally occur at night, usually awakening the person from sleep, and may be quite frightening. Though simple orthopnea may be relieved by sitting upright at the side of the bed with legs dependent, in the patient with paroxysmal nocturnal dyspnea, coughing and wheezing often persist even in this position.
Paroxysmal nocturnal dyspnea may be caused in part by the depression of the respiratory center during sleep, which may reduce arterial oxygen tension, particularly in patients with interstitial lung disease and reduced pulmonary compliance. Moreover, when in the horizontal position there is redistribution of blood volume from the lower extremities and splanchnic beds to the lungs. In normal individuals this has little effect, but in paroxysmal nocturnal dyspnea patients in whom the additional volume cannot be pumped out by the left ventricle because of disease, there is a significant reduction in vital capacity and pulmonary compliance with resultant shortness of breath.
