Introduction. The rapid development of the chemical industry in the Russian Federation is accompanied by an increase in the production and storage of highly toxic substances belonging to the group of pulmonotoxicantsare able to induce lung injury, the most severe form of which is toxic pulmonary edema (TPE). The treatment of TPE includes medication and respiratory therapy, but such a combination turns out to be insufficient, and therefore the development of new methods of treatment of the alveolar stage is an important task of modern medicine. One such approach is the use of therapeutic hypothermia, which can reduce the severity of TPE in general and the alveolar stage in particular. Recently, the use of various options for liquid ventilation of the lungs with perfluorocarbon (PFC) liquids for the induction of therapeutic hypothermia has attracted increasing attention from specialists. This article will present the results of an experimental assessment of the effect of hypothermia induced by BAL with PFC fluids on the course of the alveolar stage of toxic pulmonary edema.

The study aims to determine the effect of hypothermia induced by bronchoalveolar lavage with a pre-cooled PFC liquid on the course of the alveolar stage of toxic pulmonary edema.

Materials and methods. The authors conducted a study on male Wistar rats aged 4 months, weighing 200–220 g. TPE was modeled by intratracheal administration of 0.1 m HCl solution at a dose of 2 ml/kg. Specialists pre-injected atropine into the animals, then anesthetized, intubated with cannulas, injected a model substance and connected to a ventilator. After that, the animals were randomized by weight into two groups of 6 individuals each. In animals of the experimental and control groups, with a decrease in oxygen saturation (SpO2) below 80%, the researchers performed 2 procedures of bronchoalveolar lavage (BAL) with PFC liquid in a single dose of 2.0 ml / kg, with different temperatures. Perfluorodecalin was used as a PFC liquid. In the experimental group, the temperature of the PFC liquid during BAL was 0.5°C, in the control group — 38.0°C. Specialists recorded heart rate (HR), oxygen saturation, rectal temperature (Trect) and duration of survival.

Results. Immediately after instillation of 0.1 M HCl solution, all animals showed a sharp decrease in SpO2 (from 97±1.3 to 64±11.5) and heart rate (HR), (from 269±8.7 to 123±24.5). Recovery of indicators was observed after administration of atropine sulfate. Over the next 25–30 minutes, the following signs appeared and subsequently intensified: a decrease in SpO2 below 80%, an increase in heart rate (HR) to 302±11.4 beats/min, the presence of wet wheezing in the lungs and the release of exudate from the endotracheal catheter. In response to the BAL, all animals showed an increase in SpO2 and a decrease in heart rate. So, in the control, in response to the BAL, SpO2 increased by 8.0±2.5%, and heart rate decreased by 21.0±5.4 beats /min. While in the experimental group there was an increase in SpO2, which was 11.0±3.1%, and a decrease in heart rate by 57.0±10.2 beats/min. At the same time, during the experiment, the researchers observed an increase in temperature in the control group by 0.08±0.02°C, and in the experimental group — its decrease by 0.70±0.07°C. The average survival time of animals in the control and experimental groups was 64.8±2.2 minutes and 91.2±5.9 minutes, respectively.

Conclusion. The use of BAL PFC liquids with a low temperature makes it possible to increase the survival time of small laboratory animals in the alveolar stage of TPE due to the development of local and general hypothermia. The development of local hypothermia during BAL of the lungs makes it possible to remove a significant amount of edematous fluid, which, in turn, manifests itself in less pronounced respiratory and systemic hemodynamic disorders.

Ethics. Studies involving laboratory animals were conducted in compliance with the following regulations: Helsinki Declaration of 2000 «On humane treatment of animals», Order of the Ministry of Health of the USSR No. 755 dated 08/12/1977 «Rules for carrying out work using experimental animals», Order of the Ministry of Health and Social Development of Russia No. 199n dated 04/01/2016 «On approval of the rules of laboratory practice». The research protocol was approved by the Ethics Committee of the Izmerov Research Institute of Occupational Health (Protocol No. 4 dated May 25, 2022).

Contribution:Isabekov N.R. — research concept and design, data collection and processing, text writing, editing;Tonshin A.A. — concept and design of the study, editing;Bonitenko E.Y. — concept and design of the study, editing;

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

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

Received: 17.05.2024 / Accepted: 20.05.2024 / Published: 20.06.2024