Page 502 - Clinical Small Animal Internal Medicine

470 Section 6 Gastrointestinal Disease

Intraluminal Contrast Agents our knowledge regarding barium peritonitis is from
VetBooks.ir Barium Sulfate human medicine but the small number of reported reac­
tions in small animals seem to be similar. If large amounts
Barium sulfate suspension is the most commonly used
contrast agent for gastrointestinal radiographic studies of barium are spilled into the peritoneal cavity, profound
hypovolemia can develop secondary to exudation of
in veterinary medicine. Barium sulfate is a white crystal­ large quantities of fluid associated with the chemical
line powder, which is inert and does not support bacte­ peritonitis. Furthermore, bacterial contamination may
rial growth. Coating of the mucosa of the gastrointestinal lead to sepsis and shock within hours. If a barium leakage
tract or opacification of the lumen of the gastrointesti­ occurs, immediate treatment should be started, includ­
nal tract can require different barium formulations. ing intravenous fluid therapy and antibiotic adminis­
Throughout the gastrointestinal tract, the pH, type, and tration due to the commonly associated bacterial
amount of mucus and type of mucosa vary and therefore contamination. Once the patient is stabilized, abdominal
optimal coating in one segment does not necessarily surgery is commonly performed. However, barium can
result in optimal coating in another segment. be difficult to remove surgically as new barium formula­
Aspiration of small amounts of barium formulations is
of very little clinical significance. Barium within the tra­ tions can adhere strongly to the peritoneum.
chea and main bronchi is usually cleared within 30 min­
utes. If barium aspiration is more extensive, it is retained Negative Contrast Agents
within the interstitium of the lungs and a very slow Air is one of the cheapest contrast agents for gastrointes­
decrease of barium in the lungs might be noted over sev­ tinal studies. In veterinary patients, it is most commonly
eral months to years (Figure 48.1). If diffuse extensive used to outline the colon, especially in patients where a
alveolar infiltration of barium occurs throughout the small intestinal foreign body is suspected. Another appli­
lungs, though, this can lead to death of the patient. cation is in double contrast studies of the gastrointestinal
Therefore, if major concerns for aspiration exist before tract; the most common application of this technique is
the study, nonionic iodinated contrast agents should be in evaluating the stomach for the presence of a foreign
considered. body or to identify the location of the colon and differen­
Hypersensitivity reactions to barium have not been tiate the colon from small intestine in cases of intestinal
reported in veterinary medicine, but have been reported obstruction.
rarely in human medicine.
Barium leakage into the peritoneal cavity can occur Iodinated Contrast Agents
due to a preexisting perforation of the gastrointestinal Water‐soluble, iodine‐containing contrast agents are
tract or secondary to a procedure such as a barium most commonly used for gastrointestinal imaging when
enema. In veterinary medicine, it is commonly accepted esophageal or gastrointestinal perforations are sus­
that the suspicion of gastrointestinal perforation is a pected. However, the role of water‐soluble iodinated
contraindication for barium studies in patients. Most of contrast agents and the merit of these compounds for

(a) (b)

Figure 48.1 Left lateral (a) and ventrodorsal (b) radiographs of the thorax of a dog illustrating a previous aspiration of barium
contrast agent, which occurred during a contrast radiographic study performed six years before. The barium is persistently present
in the parenchyma of the right and left caudal as well as accessory lung lobes. Barium has localized to the tracheobronchial lymph
nodes (arrows), which has no clinical significance.