2-11. LABORATORY STUDIES

a. Sputum is collected and studied for the presence of white blood cells, bacteria, and abnormal cells. Cultures of sputum may be done to determine sensitivity or resistance to drugs when the physician must choose an antibiotic therapy.

b. Pleural fluid will accumulate in the parietal cavity in abnormal amounts in certain disease conditions. The fluid is studied to determine the cause of the abnormal accumulation. Pleural fluid is normally obtained by aspiration. This procedure is called thoracentesis and will be discussed in another section.

c. Arterial blood gas (ABG) studies provide a means of assessing the adequacy of ventilation and oxygenation, and help assess the acid-base state of the body.

2-12. OTHER STUDIES

a. X-rays of the chest show the position of normal structures within the thorax. Displacement of structures, abnormal shadows, or abnormal densities are indicative of some abnormal pathology.

b. Pulmonary function tests (PFTs) are ventilatory function tests done to detect and measure abnormalities in respiratory function. These tests involve measurement of the amount of air the patient is able to inhale and exhale.

c. Bronchoscopy is the direct visualization of the larynx, trachea, and bronchi through an instrument called a bronchoscope. Bronchoscopes may be flexible or rigid. The bronchoscope is used not only to examine, but also to diagnose bleeding sites, to excise lesions, to remove obstructions or secretions, and to collect specimens for biopsy, cytologic, or bacteriologic study.