Use of liquid ventilation for the treatment of toxic pulmonary edema

Introduction. Toxic acute respiratory distress syndrome (ARDS) caused by pulmonary toxicants represents one of the most severe forms of respiratory injury and is characterized by progressive damage to the alveolar-capillary membrane, impaired gas exchange, and the development of the toxic pulmonary edema (PE). The development of experimental models that adequately reproduce the pathogenetic mechanisms of this process is a necessary condition for preclinical evaluation of new pharmacological and respiratory therapies.

The aim of the study is to substantiate the possibility of using instillation models as an alternative to inhalation models in the study of new methods of drug and respiratory therapy for toxic PE in small laboratory animals.

Materials and methods. The study was performed on adult male Wistar rats. Toxic lung injury was induced by inhalation of chlorine gas (Cl₂) at a concentration of 35 mg/l for 15 minutes and by intratracheal instillation of 0.2M hydrochloric acid (HCl) at a dose of 2.0 ml/kg. After exposure, animals were transferred to mechanical ventilation. Clinical signs, oxygen saturation (SpO₂), heart rate (HR), survival time, development of the alveolar stage of pulmonary edema, and necropsy findings were assessed.

Results. It was shown that both inhalation of chlorine gas and intratracheal instillation of HCl solution lead to the formation of a reproducible experimental model of toxic PE. In both models, marked hypoxemia was observed with a decrease in SpO₂ below 80% on average 25–30 minutes after the start of the experiment, tachycardia up to 280–309 beats/min, development of clinical signs of the alveolar stage of toxic pulmonary edema, and a lethal outcome. The mean overall survival time was 30.6±3.3 minutes in the instillation model and 41.6±3.0 minutes in the inhalation model; survival time in the alveolar stage was 12.5±1.1 and 13.5±4.5 minutes, respectively. Necropsy in all cases revealed a large amount of edematous fluid in the trachea and bronchi, pulmonary congestion, and absence of aerated lung areas.

Limitations. The study was conducted on a limited number of animals of a single species (Wistar rats), which may limit the extrapolation of the obtained results to other species and to humans. In addition, the modeling was performed under conditions of acute toxicant exposure and did not account for possible long-term effects. It should also be noted that the instillation route of administration does not fully reproduce the physiological features of inhalation exposure to the toxicant.

Conclusions. The developed inhalation and instillation models of toxic pulmonary edema, reproducing a severe form of toxic acute respiratory distress syndrome in Wistar rats, are pathogenetically substantiated, comparable in their main characteristics, and can be considered complementary approaches for experimental modeling of lung injury caused by pulmonary toxicants, with potential application in the preclinical evaluation of drug efficacy and respiratory therapy methods, as well as in the study of the pathogenesis of these conditions.

Ethics. The study was conducted in accordance with the ethical principles of the Declaration of Helsinki. The Clinical Study Protocol was reviewed at a meeting of the local Ethics Committee of Izmerov Research Institute of Occupational Health. Protocol No.4 of May 25, 2022.

Contribution:
Bonitenko E.Yu. — concept and design of the study, writing text, editing;
Isabekov N.R. — data collection and processing, text writing;
Tonshin A.A. — study design, development of an experimental sample of a liquid artificial lung ventilation device, text writing;
Blintsova N.V. — data collection and processing;
Krikunov O.V. — data collection and processing;
Gerasimidi S.K. — data collection and processing;
Tkachuk Y.V.— data collection and processing.

Funding. The work was performed within the framework of the state assignment, the subject code FGFE-2024-0003.

Conflict of interests. The authors declare no conflict of interests.

Received: 10.03.2026 / Accepted: 13.04.2026 / Published: 25.04.2026

1. Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing. State Report. On the State of the Sanitary and Epidemiological Welfare of the Population in the Russian Federation in 2021–2022. Moscow; 2023:145–164 (in Russian).

2. Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing. State report. On the state of sanitary and epidemiological well-being of the population in the Russian Federation in 2023. Moscow: Federal State Budgetary Institution "National Medical Research Center of Rospotrebnadzor"; 2023:150–173 (in Russian).

3. Malek R., Soufi S. Pulmonary edema. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. https://www.ncbi.nlm.nih.gov/books/NBK557611/

4. Ware L.B., Matthay M.A. Clinical practice. Acute pulmonary edema. N. Engl. J. Med. 2005; 353(26): 2788–2796. https://doi.org/10.1056/NEJMcp052699

5. Sureka B., Bansal K., Arora A. Pulmonary edema — cardiogenic or noncardiogenic? J. Family Med. Prim. Care. 2015; 4(2): 290. https://doi.org/10.4103/2249-4863.154684

6. Björkbom D.M., Brabrand M. Delayed pulmonary edema following toxic inhalation. Acute Med. 2018; 17(4): 456–462. https://doi.org/10.52964/AMJA.0732

7. Huynh Tuong A., Despréaux T., Loeb T. et al. Emergency management of chlorine gas exposure — a systematic review. Clin. Toxicol. (Phila). 2019; 57(2): 77–98. https://doi.org/10.1080/15563650.2018.1519193

8. Bercker S., Petroff D., Polze N. et al. ECMO use in Germany: An analysis of 29,929 ECMO runs. PLoS One. 2021; 16(12): 1–9. https://doi.org/10.1371/journal.pone.0260324

9. Marino P.L. The ICU Book. 2nd ed. Moscow; 2022: 522–529. ISBN 978-5-9704-1399-9 https://clck.ru/3T6f34 (in Russian).

10. Bonitenko E.Y., Kashuro V.A., Basharin V.A. Modeling issues in experimental toxicology. Russian Journal of Occupational Health and Industrial Ecology [Med. truda i prom. ekol.]. 2022; 62(11): 718–732. https://doi.org/10.31089/1026-9428-2022-62-11-718-732 (in Russian).

11. Pauluhn J. Acute nose‑only exposure of rats to phosgene. Part I: concentration × time dependence of LC50s, nonlethal‑threshold concentrations, and analysis of breathing patterns. Inhal Toxicol. 2006; 18(6): 423–435. https://doi.org/10.1080/08958370600563680

12. Leustik M., Doran S., Bracher A., Williams S., Squadrito G.L., Schoeb T.R. et al. Mitigation of chlorine‑induced lung injury by low‑molecular‑weight antioxidants. Am. J. Physiol. Lung. Cell. Mol. Physiol. 2008; 295(5): 733–743. https://doi.org/10.1152/ajplung.90240.2008

13. Yadav A.K., Doran S.F., Samal A.A. et al. Mitigation of chlorine gas lung injury in rats by postexposure administration of sodium nitrite. Am. J. Physiol. Lung Cell. Mol. Physiol. 2011; 300(3): 362–369. https://doi.org/10.1152/ajplung.00278.2010

14. Meulenbelt J., Dormans J.A., Marra M., Rombout P.J., Sangster B. Rat model to investigate the treatment of acute nitrogen dioxide intoxication. Hum. Exp. Toxicol. 1992; 11(3): 179–187. https://doi.org/10.1177/096032719201100306

15. Appelman L.M., Ten Berge W.F., Reuzel P.G. Acute inhalation toxicity study of ammonia in rats with variable exposure periods. Am. Ind. Hyg. Assoc. J. 1982; 43(9): 662–665. https://doi.org/10.1080/15298668291410387

16. Perkins M.W., Wong B., Tressler J., Coggins A., Rodriguez A., Devorak J. et al. Assessment of inhaled acute ammonia‑induced lung injury in rats. Inhal. Toxicol. 2016; 28(2): 71–79. https://doi.org/10.3109/08958378.2015.1136715

17. Lachmann B., Robertson B., Vogel J. In vivo lung lavage as an experimental model of the respiratory distress syndrome. Acta Anaesthesiol. Scand. 1980; 24(3): 231–236. https://doi.org/10.1111/j.1399-6576.1980.tb01541.x

18. Hartog A., Vazquez de Anda G.F., Gommers D., Kaisers U., Verbrugge S.J., Schnabel R. et al. Comparison of exogenous surfactant therapy, mechanical ventilation with high end‑expiratory pressure and partial liquid ventilation in a model of acute lung injury. Br. J. Anaesth. 1999; 82(1): 81–86. https://doi.org/10.1093/bja/82.1.81

19. Hou S., Ding H., Lv Q., Yin X., Song J., Landén N.X. et al. Therapeutic effect of intravenous infusion of perfluorocarbon emulsion on LPS‑induced acute lung injury in rats. PLoS One. 2014; 9(1): 1–9. https://doi.org/10.1371/journal.pone.0087826

20. Basoalto R., Damiani L.F., Bachmann M.C., Fonseca M., Barros M., Soto D. et al. Acute lung injury secondary to hydrochloric acid instillation induces small airway hyperresponsiveness. Am. J. Transl. Res. 2021; 13(11): 12734–12741. https://clck.ru/3T6fHa

21. Oliveira W.R., Silva I.D., Simões R.S. Fuchs L.F., Oliveira-Filho R.M., Oliveira-Júnior I.S. Effects of prone and supine position on oxygenation and inflammatory mediator in a hydrochloric acid‑induced lung dysfunction in rats. Acta Cir. Bras. 2008; 23(5): 451–455. https://doi.org/10.1590/s0102-86502008000500011

22. Oliveira‑Junior I.S., Maganhin C.C., Carbonel A.A., Monteiro C.M., Cavassani S.S., Oliveira-Filho R.M. Effects of pentoxifylline on TNF‑alpha and lung histopathology in HCl‑induced lung injury. Clinics. 2008; 63(1): 77–84. https://doi.org/10.1590/s1807-59322008000100014

23. Hu H., Chen J., Shao Y., Tang Y., Dun Y., Memet O. et al. Establishment of rat model for aspiration pneumonia and potential mechanisms. Exp. Med. 2025; 8(6): 1105–1118. https://doi.org/10.1002/ame2.12566

24. Hirschl R.B., Parent A., Tooley R. et al. Liquid ventilation improves pulmonary function, gas exchange, and lung injury in a model of respiratory failure. Ann. Surg. 1995; 221(1): 79–88. https://doi.org/10.1097/00000658-199501000-00010

25. Hirschl R.B., Tooley R., Parent A., Johnson K., Bartlett R.H. Evaluation of gas exchange, pulmonary compliance, and lung injury during total and partial liquid ventilation in the acute respiratory distress syndrome. Crit. Care Med. 1996; 24(6): 1001–1008. https://doi.org/10.1097/00003246-199606000-00021

26. Luo S., Trübel H., Wang C., Pauluhn J. Phosgene- and chlorine-induced acute lung injury in rats: comparison of cardiopulmonary function and biomarkers in exhaled breath. Toxicology. 2014; 326(2–3): 109–118. https://doi.org/10.1016/j.tox.2014.10.010

27. Ågren L., Elfsmark L., Akfur C., Hägglund L., Ekstrand‑Hammarström B., Jonasson S. et al. N-acetyl cysteine protects against chlorine-induced tissue damage in an ex vivo model. Toxicol Lett. 2020; 322: 58–65. https://doi.org/10.1016/j.toxlet.2020.01.006

28. Isabekov N.R., Tonshin A.A., Krikunov O.V., Bonitenko E.Yu. The use of gas-liquid artificial lung ventilation in acute inhalation chlorine poisoning (experimental study). Russian Journal of Occupational Health and Industrial Ecology [Med. truda i prom. ekol.]. 2025; 65(1): 4–17. https://doi.org/10.31089/1026-9428-2025-65-1-4-17 (in Russian).

29. Isabekov N.R., Tonshin A.A., Bonitenko E.Yu. Substantiation of the possibility of using bronchoalveolar lavage with perfluorocarbon fluids for the treatment of the alveolar stage of toxic pulmonary edema. Russian Journal of Occupational Health and Industrial Ecology [Med. truda i prom. ekol.]. 2024; 64(2): 105–110. https://doi.org/10.31089/1026-9428-2024-64-2-105-110 (in Russian).

30. Isabekov N.R., Tonshin A.A., Bonitenko E.Yu. Justification of the possibility of using liquid artificial lung ventilation for the treatment of acute respiratory distress syndrome of toxic genesis. Russian Journal of Occupational Health and Industrial Ecology [Med. truda i prom. ekol.]. 2024; 64(8): 506–517. https://doi.org/10.31089/1026-9428-2024-64-8-506-517 (in Russian).

31. Finney D.J. Probit Analysis. 2nd ed. New York: Cambridge University Press; 1952.

32. Prozorovsky V.B. Use of the least squares method for probit analysis of mortality curves. Pharmacol Toxicoly. 1962; 25(1): 115–119. https://elibrary.ru/zcogzr (in Russian).

33. Bailey N.T.J. Statistical Methods in Biology. Moscow: Mir; 1963 (in Russian).

34. Rebrova O.Y. Statistical Analysis of Medical Data Using STATISTICA. Moscow: Media Sfera; 2002. https://elibrary.ru/uiszqm (in Russian).

35. Hall J.E. Guyton and Hall Textbook of Medical Physiology. 13th ed. Philadelphia: Elsevier; 2015. https://clck.ru/3T6fpt

36. Barcroft J., Camis M. The dissociation curve of blood. J. Physiol. 1909; 39(2): 118–142. https://doi.org/10.1113/jphysiol.1909.sp001330

37. Ranieri V.M., Rubenfeld G.D, Thompson B.T. et al. Acute respiratory distress syndrome: The Berlin definition. JAMA. 2012; 307(23): 2526–2533. https://doi.org/10.1001/jama.2012.5669

38. Murray J.F., Matthay M.A., Luce J.M. et al. An expanded definition of the adult respiratory distress syndrome. Am. Rev. Respir Dis. 1988; 138(3): 720–723. https://doi.org/10.1164/ajrccm/138.3.720