Methods that can be used to investigate dyspnoea in a newly referred patient http://ow.ly/EsQW307U9hd
Dyspnoea is a multifactorial symptom, defined by the American Thoracic Society as “a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity” [1]. Dyspnoea is caused by a wide range of conditions, ranging from asthma to pulmonary embolism, and including such nonrespiratory factors such as diabetic ketoacidosis. A patient with asthma who is aware of an increase in the muscular work of breathing during an attack, another patient with a pneumothorax experiencing increased efferent nerve stimulation from pulmonary stretch receptors and a third patient with type 1 respiratory failure would all describe themselves as “breathless”, but for very different physiological reasons. Identifying the exact source of the patient’s symptoms can be a lengthy process.
Cough and breathlessness are two of the most commonly reported respiratory symptoms with many possible causes that may require significant investigation before the cause is identified. After potential organic diseases such as asthma, chronic obstructive pulmonary disease (COPD), interstitial lung disease and pulmonary vascular disease have been investigated and eliminated, a potential functional diagnosis can be considered.
Much of the published literature surrounding the investigation of either acute or chronic hyperventilation has centred on patients with anxiety, depression and panic disorder but patients with a pre-existing respiratory condition may also experience periods of acute or chronic hyperventilation. Although most published data refer to asthma [2], other conditions such as COPD and pulmonary fibrosis can also be associated with hyperventilation.
This article will briefly describe methods that can be used to investigate dyspnoea in a newly referred patient. Methods of assessing functional breathlessness and cough when other investigations have been found to be normal, or where the degree of symptoms reported by the patient is out of proportion to any abnormalities found, will also be discussed. No mention will be made of the treatment of either functional cough or breathlessness.
It is assumed that readers will have access to a clinical respiratory physiology laboratory that is equipped to perform spirometry, make measurements of transfer factor and lung volumes, and carry out exercise tests, preferably a cardiopulmonary exercise test.