A comprehensive respiratory assessment of the patient presenting with symptoms such as cough, breathlessness or wheeze, is essential if appropriate, timely interventions are to be commenced. Clinical assessment alone, however, does not always give sufficient information to ascertain the underlying reasons for the symptoms presented. Additional investigations may be required to determine the disordered physiology giving rise to respiratory distress. This chapter discusses the investigations which inform diagnosis and management of patients with a range of respiratory symptoms.

The chest X-ray (CXR) is a non-invasive painless investigation that gives images of the heart, lungs, airways, blood vessels and the bones of the spine and chest (Figure 14.1). X-ray radiation penetrates soft tissue easily but does not penetrate hard tissue. Areas where radiation cannot penetrate such as bones appear white on the film, with air-filled cavities appearing black. Organs and fat have a darker grey appearance, whilst water appears a lighter grey. Problems such as pneumonia, heart failure (Figure 14.1), pneumothorax and lung cancer can be identified. The sharpest films are obtained in the X-ray department using the standard PA (posterior–anterior) and lateral view. For those who are acutely unwell a portable CXR is required, with the machine brought to the bedside. A portable CXR takes an anterior–posterior (AP) view (or from front to back).