Lung injury induced by the pulmonary instillation of povidone-iodine in rats

Purpose Povidone-iodine (polyvinylpyrrolidone iodine, PI), which is commonly used as a pre- and postoperative oral antiseptic, has been reported to cause pneumonia secondary to its pulmonary aspiration. Because no studies have yet investigated the underlying mechanisms of PI-induced pneumonia, we conducted an animal study to analyze the effect of PI on the lung following its pulmonary instillation. Methods The lungs of 61 male Sprague–Dawley rats (150–250 g) were instilled with varying volumes of either phosphate-buffered saline or PI solutions varying in strength from 0.01% to 10%. The lungs were harvested from the rats 1 h or 1, 3, 5, 7, 14, or 21 days after instillation for radiologic examination, macroscopic and light and scanning electron microscopic assessment, and an assessment of pulmonary toxicity using an MTT-based cytotoxicity assay. Results Macroscopically, atelectasis was the primary pulmonary lesion after PI instillation. The primary light and scanning electron microscopic findings were an initial inflammatory phase with edema, alveolar rupture, and leukocyte infiltration into the pulmonary interstitium, which progressed into a phase of lung parenchyma loss, and then resolved itself with scar tissue formation. Lung tissue viability following 1-day exposure to 0.01%, 0.1%, 1%, or 5% PI progressively decreased in a significant dose-dependent manner. Conclusions PI aspiration can cause lung injury, including pulmonary fibrosis.