Intravenous administration of hyperoxygenated solution attenuates pulmonary edema formation in phosgene-induced acute lung injury in rabbits

Abstract

Background: The aim of this study was to investigate the post-treatment effect of intravenous hyperoxygenated solution (HOS) on pulmonary parameters in rabbits whole-body-exposed to the toxic gas phosgene.

Materials and methods: Twenty-four New Zealand rabbits were divided into four groups randomly: rabbits were exposed whole-body to either filtered room air or 539 ppm phosgene for 5 minutes followed by room air washout for 5 minutes. Phosgene-exposed group (exposed to phosgene without treatment, PH group); Control group (exposed to air, Control group); Lactate Ringer's solution (LRS)-treated group (intravenous infusion of LRS by 30 ml·kg-1 after phosgene exposure, LRS group); Hyperoxygenated solution (HOS)-treated group (intravenous infusion of HOS after phosgene exposure by 30 mL·kg-1, HOS group). Arterial blood was collected for blood gas analysis at 1, 3, 8, and 12 hours after phosgene or air exposure. Rabbits were put to death 12 hours after exposure. Lung edema was assessed gravimetrically by measuring tissue wet/dry weight ratio (W/D) and lung coefficient (LC). Bronchoalveolar lavage (BAL) was performed and fluid was analyzed for total maloaldehyde (MDA), glutathione peroxidase (GSH-Px), and protein concentration. Lungs were perfused with saline to remove blood, snap-frozen in liquid nitrogen (N2), analyzed for tissue reduced glutathione (GSH) and oxidized glutathione (GSSG). Parts of lung tissues were reserved for histopathology examination.

Results: In the PH, LRS, and HOS groups, phosgene inhalation caused serious lung edema, W/D and LC, lung tissue GSSG, BALF MDA, and protein content increased significantly. Meanwhile, PaO2, lung tissue GSH, and BALF GSH-Px decreased markedly. However, after HOS treatment in the HOS group, PaO2 was clearly higher than that in the PH group and LRS group at 3, 8, 12 hours (P < 0.01). W/D and LC, lung tissue GSSG, BALF MDA, and protein content in the HOS group were apparently lower than that in the PH group and LRS group (P < 0.01). In the HOS group, lung tissue GSH and BALF GSH-Px increased compared with both PH and LRS group, respectively. There was no difference on lung tissue GSH among the PH, LRS, and HOS groups (P > 0.05).

Conclusions: Intravenous HOS infusion after phosgene exposure can clearly lessen phosgene-induced lung edema formation, lipid peroxidatic reaction, and ameliorate hypoxemia associated with phosgenismus; it is a safe, simple, and effective measure to protect animals from phosgene-induced lung injury.