Читать книгу Respiratory Medicine - Stephen J. Bourke - Страница 44

Dyspnoea (breathlessness) is something everyone understands but no one can satisfactorily define. It is a subjective sensation and thus as much about the mind’s interpretation of the signals it receives from the body as about what’s going on in the lungs. Dyspnoea is an unpleasant sensation, an awareness of breathing that seems inappropriately difficult for the demands that have been placed upon the body. It is not tachypnoea (increased respiratory rate), which is a sign noted by the doctor. For example, an athlete at the end of a modest training run will be tachypnoeic but is unlikely to complain of breathlessness.

In history taking, when attempting to determine the cause of dyspnoea, careful assessment includes taking note of the speed of onset, progression, periodicity and precipitating/relieving factors. The severity of dyspnoea is graded according to the patient’s exercise tolerance (e.g. dyspnoeic on climbing a flight of stairs or at rest). Onset may be sudden, as in the case of a pneumothorax, or gradual and progressive, as in chronic obstructive pulmonary disease (COPD). An episodic dyspnoea pattern is characteristic of asthma, with symptoms typically being precipitated by cold air or exercise and often displaying diurnal variability (varying with the time of day). Orthopnoea is dyspnoea that occurs when lying flat and is relieved by sitting upright. It is a characteristic feature of pulmonary oedema or diaphragm paralysis but can be found in most respiratory diseases if very severe. Paroxysmal nocturnal dyspnoea (PND) is the phenomenon of waking up breathless at night. Most medical students assume this implies pulmonary oedema, but it is also a cardinal feature of asthma. An exploration of other features of these two conditions is needed before a conclusion about cause can be drawn.

Table 2.1 Main respiratory symptoms

Dyspnoea (Breathlessness)WheezeCoughSputumHaemoptysisChest pain

It is important to note what words the patient uses to describe the symptoms: ‘tightness in the chest’ may indicate breathlessness or angina. Dyspnoea is not a symptom that is specific to respiratory disease and it may be associated with various cardiac diseases, anxiety, anaemia and metabolic states such as ketoacidosis.