Fluoroscopy

In fluoroscopy, a continuous stream of X-rays passes through the patient, casting shadows of the heart, lungs, and diaphragm on a fluorescent screen. Because fluoroscopy reveals less detail than standard chest radiography, it's indicated only when diagnosis requires visualization of physiologic or pathologic motion of thoracic contents ­for example, to rule out paralysis in patients with diaphragmatic elevation.

Purpose

• To assess lung expansion and contraction during quiet breathing, deep breathing, and coughing
• To assess movement and paralysis of the diaphragm (sniff test)
• To detect bronchial obstructions and pulmonary disease

Patient preparation

• Explain to the patient that this test assesses respiratory structures and their motion.
• Describe the test, including who will perform it, where it will take place, and its expected duration (usually 5 minutes).
• Tell the patient that he'll be asked to follow specific instructions - for example, to breathe deeply and cough ­while X-ray images depict his breathing.
• Instruct him to remove all jewelry within the X-ray field.

Procedure and posttest care

• If necessary, assist with positioning the patient.
• Move cardiac monitoring cables, I.V. tubing from subclavian lines, pulmonary artery catheter lines, and safety pins as far from the X-ray field as possible.
• During the test, the patient's cardiopulmoniry motion is observed on a screen. Special equipment may be used to intensify the images, or a videotape recording of the fluoroscopy may be made for later study.

Precautions

• Fluoroscopy is contraindicated during pregnancy.
• If the patient is intubated, check that no tubes have been dislodged during positioning.
• To avoid exposure to radiation, leave the room or the immediate area during the test; if you must stay in the area, wear a lead-lined apron.

Normal findings

Normal diaphragmatic movement is synchronous and symmetrical. Normal diaphragmatic excursion ranges from ¾" to 1 5/8 " (2 to 4 cm).

Abnormal findings

Diminished diaphragmatic movement may indicate pulmonary disease. Increased lung translucency may indicate loss of elasticity or bronchial obstruction. In elderly patients, the lowest part of the trachea may be displaced to the right by an elongated aorta.

Diminished or paradoxical diaphragmatic movement may indicate paralysis of the diaphragm; however, fluoroscopy may not detect such paralysis in patients who compensate for diminished diaphragm function by forcefully contracting their abdominal muscles to aid expiration.

Interfering factors

• Failure to remove all metal objects within the X-ray field (possible poor imaging).