ABSTRACT
Patients usually present with pneumonia in four ways to a Critical Care Unit: community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), and aspiration Pneumonia. The diagnostic criterion for each category of pneumonia is different. General investigations that can be performed for patients suspected of pneumonia are arterial blood gases (ABG), full blood count (FBC), urea and electrolytes, liver function test, C-reactive protein (CRP), and chest X-ray. Community-acquired pneumonia is defined currently by the British Thoracic Society as 'an acute illness with radiographic shadowing, which was at least segmental or present in more than one lobe and was not known to be previously present or due to other causes'. Chest X-rays should be performed for these patients along with appropriate blood test. It is common to find patients that have been admitted to Critical Care units that will have underlying chest infections whether this is CAP, HAP or aspiration.
