COMPUTERIZED TOMOGRAPHY

COMPUTERIZED TOMOGRAPHY – Reference Values, Purposes, Indications, General Instructions, Nursing Considerations, Nursing Care Before the Procedure, Procedure, Nursing Care After the Procedure, Interfering Factors and Contraindications

Computed tomography (CT) scan provides cross-sectional views of the chest by passing and X-ray beam from a computerized scanner through the body at different angles and depths. The CT scan provides a three-dimensional image of the lungs, allowing the doctor to visualize the abnormalities.

Contrast agents sometimes used to highlight blood vessels and to allow greater visual discrimination. By using computer to regulate the layers or slices of tissue examined, the camera rotates in a circular pattern and three-dimensional assessment of the thorax (or other body area) is possible. Still photographs are taken at each level. CT is able to visualize most abnormalities but small early lesions may be missed

REFERENCE VALUES

• Normal size, position, and shape of chest organ tissue and structures; no tumors, cysts, infection or inflammation, aneurysm, enlarged lymph nodes or fluid accumulation

PURPOSE

• Often CT studies are done before and after the intravenous administration of a contrast containing a radioactively
• CT scans are particularly helpful in identifying peripheral (pleural) or mediastinal disorders
• Spiral or helical CT scan of the chest is an alternative to the lung scan for identifying pulmonary emboli

INDICATIONS

• Configuration of the trachea or major bronchi and evaluate masses or lesions
• Tumors and abscesses
• Abnormal lung shadows

GENERAL INSTRUCTIONS

• Computerized tomography scans highlight differences in bone and soft tissue
• The images are generated by computerized synthesis of X-ray data obtained in many different direction in a cross-sectional plane or slice
• The computerized data are assembled as three-dimensional images
• CT is used to identify space-occupying lesions (masses) and shifts of structures caused by neoplasm’s, cysts, focal inflammatory lesions and abscesses of chest
• To distinguish normal tissue from abnormal masses, a contrast medium (dye) may be administered
• The CT-scan can be performed quickly, within 20 minutes

NURSING CONSIDERATIONS

• Before a CT-scan, make sure that the client has given informed consent and answer any questions about the procedures
• Explain the fasting usually is not required for a CT scan of the chest, but ask whether or not the client becomes nauseated easily; if so, adjust foot and fluid intake accordingly
• Inform the client, placed in supine. The technician moves the table from a control room to direct the study to different areas
• Inform the client, he can expect to hear mechanical noises coming from scanner
• Some clients may feel claustrophobic during the test, but assure them that it is possible to communicate with the technician
• Emphasize that the client must remain still during the scan. Unable to comply, sedation is needed
• After the test, assess the client for reactions to the contrast agent, and the quality of pulses in the limb used for injection of the contrast agent
• The client may be resume normal activities unless additional diagnostic tests are planned

NURSING CARE BEFORE THE PROCEDURE

• Inform the client that the study takes about 30 minutes to 1 hour
• Obtain a history that includes cardiac and pulmonary assessment findings, known or suspected pulmonary conditions, and results of associated laboratory tests and diagnostic procedures

PROCEDURE

• The scanner takes images at different levels and angles of the chest region, from the neck to the waist instead of the whole body
• Contrast-enhanced studies are performed by the IV administration of an iodinated contrast medium for vessel evaluation or by oral administration of a contrast medium for esophageal evaluation

NURSING CARE AFTER THE PROCEDURE

Monitor vital signs if the client has a acute or chronic cardiac or pulmonary condition

INTERFERING FACTORS

• Inability of client to remain still during procedure
• Metal objects such as jewelry within the examination field

CONTRAINDICATIONS

• Pregnancy, unless the benefits of performing the study greatly outweigh the risks to the fetus
• Allergy to iodine, if an iodinated contrast medium is to be used
• Extreme obesity
• Unstable medical status, i.e. vital signs or dehydration
• Extreme claustrophobic response that prevents the client from remaining still during procedure, unless medications are given before the study