Biliary Tract and Upper Gastrointestinal System II . Body Habitus.
In addition to body habitus, other factors that may affect the position of the stomach include stomach contents, respiration, body position (erect vs. recumbent), previous abdominal surgeries, and age. Because the upper stomach is attached to the diaphragm, whether one is in full inspiration or expiration affects the superior extent of the stomach. All abdominal organs tend to drop 1 to 2 inches (2.5 to 5 cm) in an erect position, or even farther with age and loss of muscle tone. As a technologist, correct localization of the stomach and other organs for different body types in various positions comes with positioning practice.
Hypersthenic. Generally shorter in height, with broad shoulders and hips and short torso (less distance between lower rib cage and iliac crest). Abdominal cavity is widest at upper margin.
Sthenic. Near average in height, weight, and length of torso (may be somewhat heavier than average, with some hypersthenic characteristics).
Hyposthenic/asthenic. Generally tall and thin, with long torso. (This example is somewhere between hyposthenic and asthenic.) Abdominal cavity is widest at lower margin for a true asthenic.
A second similarity is that the initial stage of each radiographic examination of the alimentary canal is carried out with fluoroscopy. Fluoroscopy allows the radiologist to
(1) observe the GI tract in motion,
(2) produce radiographic images during the course of the examination
(3) determine the most appropriate course of action for the complete radiographic examination. To view organs in motion and isolate anatomic structures is absolutely essential for radiographic examination of the upper GI tract. The structures in this area assume a wide variety of shapes and sizes, depending on body habitus, age, and other individual differences.
A third similarity is that radiographic images are recorded during, and frequently after, the fluoroscopic examination to provide a permanent record of the normal or abnormal findings. A postfluoroscopy “overhead” radiograph is being readied for exposure by the technologist after performance of fluoroscopy for an upper GI series
With increased use of digital fluoroscopy, the number of postfluoroscopy radiographs has diminished greatly. Some departments rely strictly on the digital image produced during fluoroscopy rather than any additional postfluoroscopy radiographs.
The most common positive, or radiopaque, contrast medium used to visualize the gastrointestinal system is barium sulfate (BaSO4), which is commonly referred to as just barium. Barium sulfate is a powdered, chalklike substance. The powdered barium sulfate is mixed with water before ingestion by the patient.
A mixture of barium sulfate and water forms a colloidal suspension, not a solution. For a solution, the molecules of the substance added to water must actually dissolve in the water. Barium sulfate never dissolves in the water. In a colloidal suspension, however (such as barium sulfate and water), the particles suspended in the water may tend to settle out when allowed to sit for a time.
Most barium sulfate preparations are pre-packaged, water is added to the cup and then mixed. Some barium sulfate preparations come in a liquid form, which does not require water to be added. Most of these preparations contain finely divided barium sulfate in a special suspending agent, so they tend to resist settling out and therefore stay in suspension longer. Each suspension must be well mixed before use, however. Various brands may have different smells and different flavors, such as chocolate, chocolate malt, vanilla, lemon, lime, or strawberry. Some commercial brands of barium sulfate come in a liquid form, which must be shaken thoroughly before the procedure is performed.
One drawback to the water-soluble materials is their bitter taste. Although these iodinated contrast media sometimes are mixed with carbonated soft drinks to mask the taste, they often are used “as is” or diluted with water. The patient should be forewarned that the taste may be slightly bitter.
The technologist should be aware that water-soluble contrast agents travel through the GI tract faster than barium sulfate. The shorter transit time of water-soluble contrast agents should be kept in mind if delayed images of the stomach or duodenum are ordered.
Warning: Water-soluble iodinated contrast media should not be used if the patient is sensitive to iodine, or if the patient is experiencing severe dehydration. The water-soluble contrast agent often will further dehydrate the patient.
The radiolucent contrast medium is either room air or carbon dioxide gas. To introduce room air, small pinprick holes are placed in the patient's straw. As the patient drinks the barium mixture, air is drawn into the body.
One of the best ways to reduce worker dose during fluoroscopy is to apply the following three “Cardinal Principles of Radiation Protection.” If these principles are applied correctly, dose to both the fluoroscopist and the technologist can be reduced greatly.
Shielding: Follow all shielding precautions described above, including correct use of the lead drape shield, the Bucky slot shield, and lead gloves.