Analysis of the effect of inert gas on alveolar/venous blood partial pressure by using the operator splitting method

This study aims to investigate how inert gas affects the partial pressure of alveolar and venous blood using a fast and accurate operator splitting method (OSM). Unlike previous complex methods, such as the finite element method (FEM), OSM effectively separates governing equations into smaller sub-problems, facilitating a better understanding of inert gas transport and exchange between blood capillaries and surrounding tissue. The governing equations were discretized with a fully implicit finite difference method (FDM), which enables the use of larger time steps. The model employed partial differential equations, considering convection-diffusion in blood and only diffusion in tissue. The study explores the impact of initial arterial pressure, breathing frequency, blood flow velocity, solubility, and diffusivity on the partial pressure of inert gas in blood and tissue. Additionally, the effects of anesthetic inert gas and oxygen on venous blood partial pressure were analyzed. Simulation results demonstrate that the high solubility and diffusivity of anesthetic inert gas lead to its prolonged presence in blood and tissue, resulting in lower partial pressure in venous blood. These findings enhance our understanding of inert gas interaction with alveolar/venous blood, with potential implications for medical diagnostics and therapies.

Helium Suicide, a Rapid and Painless Asphyxia: Toxicological Findings

Suicide by helium inhalation has become increasingly common in the last few decades in Europe and the US because it produces a quick and painless death. Inhaled-gas suicides can easily be assessed through death scene investigation and autopsy. However, helium is a colorless and odorless inert gas that unfortunately cannot be detected using standard toxicological analysis. A successful gas analysis was performed following the suicide of a 17-year-old female. For the detection of helium, central/peripheral blood samples and gaseous samples from the esophagus, stomach, and upper and lower respiratory airways (from the trachea and the primary left and right bronchia) were collected with a gastight syringe, ensuring minimal dilution. Qualitative analyses were positive in all gaseous samples. Quantitative analyses were performed using a special gas-inlet system with a vacuum by which the sample can be transferred to a mass spectrometer, reducing the risk of contamination. Helium concentrations were 20.16% from the trachea, 12.33% from the right lung, and 1.5% from the stomach. Based on the high levels of helium, the cause and manner of death were assessed as asphyxia suicide by inhalation of helium. Therefore, toxicological analyses should always be applied in order to gain evidence of inhaled gas in gaseous samples.

Samobójstwo przy użyciu helu – opis przypadku

W ostatnich latach obserwuje się wzrost liczby samobójstw z wykorzystaniem helu. Zgony z użyciem tego gazu są szybkie i nie towarzyszy im uczucie duszności. W niniejszej pracy przedstawiono wyniki badania pośmiertnego kobiety, która popełniła samobójstwo poprzez inhalację helu. Sekcja zwłok nie wykazała żadnych zmian pourazowych, natomiast badanie TK wykazało obecność dużej ilości gazu w naczyniach żylnych i tętniczych całego ciała oraz w jamach serca. W ocenie obrazów PMCT uwzględniono także zmiany wynikające z procesów rozkładowych. Rezultaty przeprowadzonej diagnostyki potwierdzają wyniki wcześniejszych doniesień, które wskazywały, iż wdychanie dużych ilości helu prowadzi do śmierci nie tylko (jak wcześniej sądzono) w mechanizmie wypierania tlenu, ale także poprzez powstawanie zatorów gazowych. Suicidal helium inhalation – case report A significant increase in the number of suicides with the use of helium has been observed in recent years. Deaths with its use are quick and are not accompanied by a feeling of breathlessness. This paper presents the results of a post-mortem examination of a woman who committed suicide by inhaling helium. Conventional postmortem examination did not reveal any post-traumatic changes, while a computed tomography (CT) scans showed the presence of a large amount of gas in the veins and arteries of the whole body and in the heart chambers. In the assessment of postmortem computed tomography (PMCT) images, changes resulting from putrefaction were also taken into account. The results of the diagnostics carried out confirm the results of previous reports, which indicated that inhalation of large amounts of helium leads to death not only (as previously thought) in the oxygen displacement mechanism, but also through the formation of gas embolisms.

Detection of helium in a fire victim: A case report

We report here detection of helium in specimens derived from a burn autopsy case. A male was found in a burnt bedroom. Part of a heat-denatured plastic bag, sealing tape, and flexible tubing remained on his head and neck. In addition, five helium tanks were found near him. His history in conjunction with the discovery conditions suggested a suicide attempt by inhalation of helium. The body had extensive first to fourth degree burns caused by heat. A small amount of soot was deposited in the respiratory tract. Except for the thermal burns, no other injuries were found. Toxicologically, the blood carboxyhemoglobin saturation levels were less than 6%, while combustion-derived volatile hydrocarbons such as benzene or toluene were detected in the blood. In addition, tracheal gas, gastric gas, headspace gas of lung tissue, brain, and heart blood were collected during autopsy for detection of helium. Analysis was performed using headspace gas chromatography with a thermal conductivity detector. Helium was detected in all of the samples tested. Etizolam at a low limit of therapeutic concentration or less was detected in the blood. Neither ethanol nor other drugs of abuse were detected in his blood or urine. Autopsy findings and experiments suggest that the victim inhaled helium and was still alive when a fire broke out. The cause of his death was diagnosed as death from fire and flames. The present result suggests that helium may remain in a burned body and that investigation of helium in cases of fire-related deaths is informative for determination of the cause of death or confirmation of the ante mortem involvement of helium.

Helium suicide - A suffocation or a barotrauma?

Helium is a chemically inert gas present in atmospheric air that is used in various branches of industry and in medicine. In the case of its improper use, various complications may occur, affecting mainly the respiratory tract and, in extreme cases, even result in death. Helium has also been used for committing suicide. Helium suicide is a method that does not leave characteristic macro- and microscopic post-mortem changes. A large amount of information on how to commit suicide with the use of helium can be found on the internet, which contributes to the popularization of this method in the world. In the case of incompetent use of the equipment theoretically dedicated to such suicide, death may occur not because of the suffocation, which is the most common mechanism in such cases, but because of a pressure injury of the respiratory tract, resulting in rapid damage to the alveoli in the rupture mechanism, causing massive bleeding. Helium dissipates quickly in the ambient air, and usually, its presence cannot be detected either in the blood or in the tissues. Thus, even if the material for toxicological tests is handled properly, detection of the presence of helium in a relatively short period of time after death is usually impossible or very difficult. If death due to inert gas inhalation is suspected during an autopsy, samples of biological material can be collected to be tested later by gas chromatography combined with mass spectrometry (GC-MS), but the results of the investigations are usually not helpful from the point of view of a forensic pathologist.