Contrast Agents for Swallow Studies

If you are looking for a GI tract leak—-use gastrograffin if you suspect a leak into the interstitial tissues.¬† Use Barium if you suspect a leak into the pulmonary system.

Gastrografin can cause a chemical pneumonitis in the lungs but is the contrast agent of choice if there is concern for an abdominal leak/fistula.  In contrast, barium is better tolerated by the lungs than the GI system and should be used to evaluate for airway fistulae.

Gastrografin  (Diatrizoate Meglumine)
Water-soluble iodine containing contrast medium
Water-soluble contrast agents also are absorbed rapidly from the mediastinum, so follow-up radiographic studies to assess the status of a leak are not compromised by residual contrast material in the mediastinum
Less caustic to the peritoneum and mediastinum
Believed to achieve lower level of musical detail due to its decreased opacity, may fail to reveal a significant portion of perforations or leaks
Osmolarity of gastrografin is 6-10 times that of plasma – may induce dangerous hypovolemia
Contraindicated in cases where a communication with tracheobronchial tree is suspected due to risk of chemical pulmonary edema

Barium
Inert in the lungs
Higher opacity allows for greater mucosal detail and may identify leaks not visualized with water soluble agents
Small theoretic risk that extravasated barium in the mediastinum may cause a granulomatous reaction with mediastinitis or mediastinal fibrosis, as previously shown in studies on laboratory cats

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