The use of gas-liquid artificial lung ventilation in acute inhalation chlorine poisoning (experimental study)
Authors: Isabekov Nikolay R. , Tonshin Anton A. , Krikunov Oleg V. , Bonitenko Evgenij Yu. 
Published: February 2025

Introduction. Currently, chlorine is widely used in industry and agriculture. There are thousands of industrial facilities located on the territory of the Russian Federation that have chlorine reserves in quantities that, in the event of an emergency, can lead to massive damage to people. Chlorine poisoning has stages of development of the toxic process with the development of toxic pulmonary edema (TPE). Respiratory therapy for TPE consists in the use of artificial lung ventilation (ALV) with positive pressure at the end of exhalation and an oxygen content in the inhaled mixture (FiO2) of at least 40%. Currently, scientists are actively developing methods of liquid artificial lung ventilation (LALV) using perfluorocarbon (PFC) liquids as an alternative to gas artificial lung ventilation (ALV), in particular, in the treatment of toxic pulmonary edema. This article shows the possibility of sequential cyclic use of liquid and gas (intermittent gas-liquid) artificial ventilation in combination with hypothermia in a model of acute inhalation chlorine damage in rats.
The study aims to evaluate the prospects of using intermittent gas-liquid artificial lung ventilation combined with hypothermia for the treatment of severe inhaled chlorine lesions.
Materials and methods. The authors have conducted a study on male Wister rats aged 4 months and weighing 192.1±2.3 g. Toxic pulmonary edema was initiated by 15-minute inhalation of chlorine at an estimated dose of 35 mg/l. The animals were anesthetized and then randomized into two groups, control and experimental (6 individuals each) based on inclusion criteria: decreased oxygen saturation (SpO2)<80 and increased heart rate (HR)>240 beats/min. The scientists performed artificial lung ventilation throughout the study in the control group. The animals of the experimental group were subjected to hypothermic liquid ventilation for an hour, after which they were switched to gas ventilation, and when SpO2 and heart rate dropped below acceptable values, the cycle was repeated. At the same time, the authors continued to ventilate with gas until the end of the experiment. Scientists used perfluorodecalin as a PFU liquid. They recorded heart rate, SpO2, rectal temperature, overall survival, and life expectancy.
Results. After inhalation, the researchers observed severe chlorine damage in all animals. 10 minutes after the start of ventilation in the animals of the control group, the authors observed an increase in saturation to 90% and a decrease in heart rate to 220–240 beats per minute, followed by 20–25 minutes. They also observed a rapid decrease in SpO2 to extremely low values and an increase in heart rate, which indicated inefficiency of ventilation and caused the development of adverse outcomes. In turn, in the experimental group, during the first 5 minutes after the start of liquid artificial lung ventilation (LALV), the researchers recorded a sharp decrease in heart rate to 104±3.5 beats/min. and an increase in SpO2 to 94±2.4%.
After switching to gas artificial lung ventilation (AVL), the time for lowering the controlled parameters below the permissible values was 45±7.9 minutes. 5 minutes after the start of the second liquid artificial ventilation session, all animals showed an increase in SpO2 and a decrease in heart rate, while the values of these indicators did not differ from the values recorded during the first session.
After the 2nd transfer to a gas ventilator, there was a short-term improvement in the studied indicators, followed by a deterioration that ended in an unfavorable outcome.
When studying survival, the authors found that the average duration of survival in the experimental group was 4.57 times longer than in the control group, and amounted to 190.0±6.3 and 41.6±3.0 minutes, respectively (p<0.001).
When assessing the amount of edematous fluid released during liquid artificial lung ventilation, the researchers found that during the experiment, that during the experiment, an average of 5.9±1.8 ml/kg was aspirated in animals of the experimental group. The average body temperature of the animals in the control group was 36.2±0.3°C. In turn, the animals of the experimental group showed a sharp decrease in temperature during the first 30 minutes of liquid artificial ventilation, by an average of 6.1±1.2°C. After that, the temperature stabilized and was in the range of 30–31°C until the death of the animals.
A pathoanatomic examination revealed that in the animals of the control group, a large amount of edematous fluid and foam was found in the respiratory tract and lungs, while in the experimental group, edematous fluid prevailed in the upper respiratory tract, and perfluorodecalin in the lower.
At the same time, the mass coefficients of the lungs of the control and experimental groups were 1.89±0.08% and 2.70±0.03%, respectively.
Limitations. There are quantitative restrictions on the presence of animals in the sample, as well as qualitative restrictions in experiments with animals with pulmonary edema after inhalation chlorine poisoning.
Conclusion. Inhalation seeding with chlorine in a 200-liter chamber with an estimated dose of 35 mg/l for 15 minutes leads to the lightning-fast development of toxic pulmonary edema in small laboratory animals (bypassing the stage of primary clinical manifestations and the latent period). The use of liquid artificial ventilation with PFDs makes it possible to evacuate edematous fluid from the lungs in case of toxic edema caused by severe inhalation chlorine poisoning, and thereby preserve gas exchange in the lungs. The use of intermittent hypothermic gas-liquid ventilation makes it possible to maintain gas exchange in the lungs in the case when conventional mechanical ventilation is ineffective and thus significantly (p<0.001) increase the survival time of laboratory animals by 4.57 times. The results obtained indicate the prospects for further development of respiratory support methods based on hypothermic ventilation as a treatment for severe forms of acute respiratory distress syndrome, in the case when traditional ventilation is no longer effective.
Ethics. Studies involving laboratory animals were conducted in compliance with the following regulations: the Helsinki Declaration of 2000. "On humane treatment of animals", Order of the USSR Ministry of Health 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.