Dyspnoea - Clinical Symptoms

Dyspnoea

Dyspnoea is defined as difficulty in breathing. In general dyspnoea arises from either the respiratory or cardiovascular system and it is often difficult to distinguish between them.

·        Cardiac dyspnoea is generally the result of left ventricular failure when fluid accumulates in the interstitium of the lungs. The patient may notice it on strenuous exertion initially, with gradually reducing ‘exercise tolerance’ (the distance a patient can walk before having to stop for a rest). In severe failure, patients are breath-less at rest. In any acute exacerbation of cardiac dyspnoea an underlying cause should be sought, such as ischaemia, arrhythmias or a worsening heart valve lesion.

·        Orthopnoea is defined as breathlessness on lying flat. This symptom normally arises when a patient’s exercise tolerance is already reduced. It is thought that two mechanisms are responsible for this phenomenon: a redistribution of fluid through gravity in the lungs and a pressing of the abdominal contents on the diaphragm, which reduces the vital capacity of the lungs. Many patients avoid the sensation of breathlessness by propping themselves up on pillows at night, or, in severe cases, sleeping in a chair. Orthopnoea is highly suggestive of a cardiac cause of dyspnoea, although it may also occur in severe respiratory disease due to the second mechanism.

·        Paroxysmal nocturnal dyspnoea is waking from sleep suddenly breathless. It is thought to occur by a similar mechanism to orthopnoea coupled to a decreased sensory response whilst asleep. Patients awake breath-less and anxious, they often describe having to sit up and may hang their legs over the side of the bed or go to the window to relieve the dyspnoea.

·        Cheyne–Stokes respiration is alternate cyclical hyperventilation and hypoventilation (or even apnoea). This occurs in patients with very severe left ventricular failure, in some normal individuals (often elderly), in patients with cerebrovascular disease and patients receiving opiate analgesia. It is thought that this pattern of breathing results from depression of the respiratory drive centre within the brain.

·        Patients with severe acute left ventricular failure often have a cough productive of frothy sputum, which may be blood stained. Frank haemoptysis may occur in mitral stenosis or following a pulmonary embolus. However, the major causes of frank haemoptysis are from the respiratory system.