2020 Volume 32 Issue 02 Pages 99-103
Contrast agent aspiration is an established complication of upper gastrointestinal and videofluoroscopic swallow studies (VFs). Barium sulfate (Ba) suspension is the most widely used contrast agent for VFs. The molecular biological mechanisms underlying acute and chronic responses to contrast agent (CA) aspiration in the respiratory organs remain unclear. We examined these mechanisms underlying the acute and chronic responses to three kinds of CA aspiration in the lung and studied the effects of different barium concentrations on the respiratory organs. Eight-week-old male Sprague Dawley rats were used for animal models of aspiration. We elucidated the mechanisms underlying these effects induced by CA aspiration, including Ba, ionic iodinated CA (ICA), and non-ionic iodinated CA (NICA). In the acute phase, Ba caused severe histopathologic changes and more prominent inflammatory cell infiltration in the lungs than the two other iodinated CAs. Increases in the expression of inflammatory cytokines were observed in the Ba and ICA aspiration rats. NICA did not cause any obvious histologic changes or the expression of inflammatory cytokines and fibrosis-related genes in the lungs. In the chronic phase, Ba particles remained after 30 days and caused histopathologic changes and inflammatory cell infiltration. Iodinated ICA and NICA did not result in any perceptible histologic changes. Furthermore, both low-Ba and high-Ba aspiration caused inflammatory cell infiltration in the lung at two days post aspiration with an increase in the expression of inflammatory cytokines. At 30 days post-aspiration, small quantities of barium particles remained in the lung of the low-Ba group without any inflammatory reaction. Chronic inflammation was recognized in the high-Ba group up to 30 days post aspiration. Ba caused significantly more acute and chronic lung inflammation in our rodent model than ICA or NICA. Aspirated Ba particles did not clear from the lung within one month and caused mild chronic pulmonary inflammation. Even with a small amount of low-concentration Ba aspiration (30% [w/v]), Ba particles can remain in the lung for over a month, causing sustained late effects. NICA did not cause any discernible inflammatory response in the lungs, suggesting it may be the safest contrast agent for VFs.
