Sputum Examination

A sputum sample can be obtained by expectoration, tracheal suction, or bronchoscopy (discussed later). In addition to the analysis of the amount, quality, and color of the sputum (previously discussed in Chapter 2, page 44), the sputum sample may be examined for (1) culture and sensitivity, (2) Gram stain, (3) acid-fast smear and culture, and (4) cytology.

For a culture and sensitivity study, a single sputum sample is collected in a sterile container. This test is performed to diagnose bacterial infection, select an antibiotic, and evaluate the effectiveness of antibiotic therapy. The turnaround time for this test is 48 to 72 hours. The Gram staining of sputum is performed to classify bacteria into gram-negative organisms and gram-positive organisms. The results of the Gram stain tests guide therapy until the culture and sensitivity results are obtained. Box 8-1 presents common organisms associated with respiratory disorders. All but the viral organisms can be seen on a Gram stain.

The acid-fast smear and culture is performed to determine the presence of acid-fast bacilli (e.g., Mycobacterium tuberculosis). A series of three early morning sputum samples is tested. Cytology examination entails the collection of a single sputum sample in a special container with fixative solution. The sample is evaluated under a microscope for the presence of abnormal cells that may indicate a malignant condition.

The amount, color, and constituents of the sputum are often important in the assessment and diagnosis of many respiratory disorders, including tuberculosis, pneumonia, cancer of the lungs, and pneumoconiosis. For example, yellow sputum indicates an acute infection. Green sputum is associated with old, retained secretions. Green and foul-smelling secretions are frequently found in patients with anaerobic or Pseudomonas infection. Thick, stringy, and white or mucoid sputum suggests bronchial asthma. Brown sputum suggests the presence of old blood. Red sputum indicates fresh blood.

Skin Tests

Skin tests are commonly performed to evaluate allergic reactions or exposure to tuberculous bacilli or fungi. Skin tests entail the intradermal injection of an antigen. A positive test result indicates that the patient has been exposed to the antigen. However, it does not mean that the disease is actually present. A negative test result indicates that the patient has had no exposure to the antigen. A negative test result also may be seen in patients with a depression of cell-mediated immunity (anergy), such as that which develops in human immunodeficiency virus (HIV) infections.

A bronchoscopy is a well-established diagnostic and therapeutic tool used by a number of medical specialists, including those in intensive care units, special procedure rooms, and outpatient settings. With minimal risk to the patient—and without interrupting the patient’s ventilation—the flexible fiberoptic bronchoscope allows direct visualization of the upper airways (nose, oral cavity, and pharynx), larynx, vocal cords, subglottic area, trachea, bronchi, lobar bronchi, and segmental bronchi down to the third or fourth generation. Under fluoroscopic control, more peripheral areas can be examined or treated (Figure 8-1). Bronchoscopy may be diagnostic or therapeutic.

A diagnostic bronchoscopy is usually performed when an infectious disease is suspected and not otherwise diagnosed or to obtain a lung biopsy sample when the abnormal lung tissue is located on or near the bronchi. A diagnostic bronchoscopy is indicated for a number of clinical conditions, including further inspection and assessment of (1) abnormal radiographic findings (e.g., question of bronchogenic carcinoma or the extent of a bronchial tumor or mass lesion), (2) persistent atelectasis, (3) excessive bronchial secretions, (4) acute smoke inhalation injuries, (5) intubation damage, (6) bronchiectasis, (7) foreign bodies, (8) hemoptysis, (9) lung abscess, (10) major thoracic trauma, (11) stridor or localized wheezing, and (12) unexplained cough.

A videotape or colored picture of the procedure may also be obtained to record any abnormalities. When abnormalities are found, additional diagnostic procedures include brushings, biopsies, needle aspirations, and washings. For example, a common diagnostic bronchoscopic technique, termed bronchoalveolar lavage (BAL), involves injecting a small amount (30 mL) of sterile saline through the bronchoscope and then withdrawing the fluid for examination of cells. BAL is commonly used to diagnose Pneumocystis carinii pneumonia.

Therapeutic bronchoscopy includes (1) suctioning of excessive secretions or mucous plugs, especially when lung atelectasis is forming, (2) the removal of foreign bodies or cancer obstructing the airway, (3) selective lavage (with normal saline or mucolytic agents), and (4) management of life-threatening hemoptysis. Although the virtues of therapeutic bronchoscopy are well established, routine respiratory therapy modalities at the patient’s bedside (e.g., chest physical therapy, intermittent percussive ventilation [IPV], postural drainage, deep breathing and coughing techniques, and positive expiratory pressure [PEP] therapy) are considered the first line of defense in the treatment of atelectasis from pooled secretions. Clinically, therapeutic bronchoscopy is commonly used in the management of bronchiectasis, lung abscess, smoke inhalation and thermal injuries, and lung cancer (see Bronchopulmonary Hygiene Therapy Protocol 9-2, page 120).