Liquid respiratory desaturation is a new method of preventing decompression sickness

Introduction. According to the literature data, the method of liquid ventilation for the prevention of decompression sickness (DCS) was proposed only with the condition of its initiation before compression, that excluded the physical basis of the disease — an excess of metabolically indifferent gas in the tissues. However, as the analysis shows, in most cases, the evacuation of the crew of an emergency submarine is aggravated by being in gases’ increased pressure environment. So the casualty tissues become obviously saturated with indifferent gas.

Experimental confirmation of the possibility of rapid tissues’ desaturation of nitrogen during respiration by denitrogenizated and oxygenated in a normal conditions respiratory fluid (hereinafter — the method of liquid respiratory desaturation) was obtained on the biological model of DCS of Syrian hamsters.

The study aim is an experimental substantiation of the possibility to use liquid respiratory desaturation as a method of preventing the development of decompression disorders.

Materials and methods. Scientists have performed a study on 24 mature male Syrian hamsters weighing 165–185g, aged four months, using an experimental laboratory hyperbaric stand for temporary maintenance of small laboratory animals under high pressure of a gas or liquid medium with the possibility of switching from one medium to another in isobaric conditions.The research methodology is based on the assessment of the clinical presentation of decompression disorders and the results of ultrasound examination of gas formations in the heart, large veins and liver after the fast non-stop decompression, in the background of preliminary saturation of the animal's body with indifferent gas (nitrogen) by staying in the air under the pressure 0.6 MPa (60 MWC) for six hours. The effect on experimental groups animals deferens from the control group by the period of immersion and spontaneous breathing in the respiratory fluid (20, 30 and 40 minutes) before decompression.

Results. The authors analyzed the clinical picture of acute decompression disorders. The degree of gas formation in small laboratory animals was assessed by researchers using ultrasound using a semi-quantitative method. Spontaneous breathing with the prepared liquid, lasting 30 minutes or more, made it possible to remove excess nitrogen from the body of animals of experimental groups, providing etiopathogenetic prevention of DCS before decompression. The article presents the data of morphological studies.

Conclusion. Liquid respiratory desaturation is a method of preventing decompression disorders based on the removal of metabolically indifferent gases from the body during liquid respiration, in the presence of a stress gradient from tissues into the respiratory fluid. The method allows the metabolically indifferent gases' rapid desaturation from the body by liquid ventilation before/or during decompression, thereby creating conditions of ultra-fast decompression modes without the risk of decompression 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 of 12.08.1977 "Rules for carrying out work using experimental animals", Order of the Ministry of Health and Social Development of Russia No. 199n of 01.04.2016 "On approval of the rules of laboratory practice". The protocol of the study was approved by the Ethics Committee of the Izmerov Research Institute of Occupational Health.

Contribution:
Kotsky M.A. — the concept and design of the study, data collection and processing, writing the text, editing;
Bonitenko E.Yu. — the concept and design of the study, writing the text;
Tonshin A.A. — the concept and design of the study, editing;
Rodchenkova P.V. — data collection and processing, conducting ultrasound research;
Muravskaya M.P. — data collection and processing;
Tkachuk Yu.V. — data collection and processing;
Kanibolotsky A.A. — conducting pathomorphological studies;
Kochoyan A.L. — conducting pathomorphological studies.

Funding. The study was funded by the Advanced Research Foundation, Moscow, Russian Federation.

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

Received: 17.12.2022 / Accepted: 01.01.2023 / Published: 29.01.2023

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