Hospital Acquired Pneumonia
General investigations are not necessary for the majority of patients who are managed in the community. Pulse oximeters allow for simple assessment of oxygenation. When a patient is admitted to hospital:
FBC with differential white cell count:
Total white blood cells: All the white cell types are given as a percentage, and as an absolute number per liter. A high WBC is often an indicator of infection (Osei‐Bimpong et al).
CRP (to aid diagnosis and as a baseline measure). The C-reactive protein (CRP) test is a diagnostic tool that identifies regions of inflammation (Tracy et al). CRP is a protein manufactured in the liver before dispersal into the blood which occurs a few hours after any form of tissue injury, an acute manifestation of infection, or inflammation caused by another source (Tracy et al). The CRP test can be used in adjunction with signs, symptoms and other tests in order to fully evaluate patients with HAP (Tracy et al).
Blood cultures:
Blood culture is a microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream (such as bacteremia, septicemia amongst others).
Pneumococcal and legionella urinary antigen tests:
Urine tests are administered and designed to locate the presence of both Streptococcus pneumoniae and Legionella species (Marcos et al). Two major pathogens in HAP, which also play a key role in community acquired Pneumonia. The tests are usually in conjunction with both sputum examination and blood testing due to their high specificity (Marcos et al).
CXR:
HAP may deliver signs of abnormal opacity in specific areas of the lungs, or even clear consolidation due to inflammation causing abnormal positioning of structures, such as the trachea and mediastinum (Pugin et al).
Sputum examination and culture.
Sputum Examination is a diagnostic tool used to identify bacteria and fungi located in the pulmonary facet (Musher et al). Samples are often obtained through expectorating or in some cases an induced saline can produce the required volumes from lab testing. HAP normally produces sputum in a thick and purulent form, which is common in more cases of infection (Musher et al).
Blood gases:
Blood gases will demonstrate how well both the respiratory and the renal systems are functioning (Marc et al). In terms of HAP ABG’s can be used to gain insight into the patient’s oxygen saturation levels as well as demonstrate incidences of both acidosis and alkalosis, both of which can occur due to poor ventilation (Marc et al).
Aspiration of pleural fluid (for biochemistry and culture).
Chest aspiration is a diagnostic tool used to investigate the cause of pleural fluid or to improve respiration rates that have dropped due to accumulated fluid (Blackmore et al). Samples of the pleural fluid are sent for analysis which includes cytology for malignant cells and bacteriology for identification of foreign bacteria (Blackmore et al).
