Rom J Morphol Embryol 2019, 60(1):125–131 ISSN (print) 1220–0522 ISSN (online) 2066–8279 ORIGINAL PAPER Co-morbidities in the multiple victims of the silent killer in carbon monoxide poisoning CAMELIA-OANA MUREŞAN 1) , ROXANA EUGENIA ZĂVOI 2) , RALUCA OANA DUMACHE 1) , CRIS VIRGILIU PRECUP 3) , VERONICA CIOCAN 1) , OVIDIU ŞTEFAN BULZAN 3) , CHAROULA FLOROU 4) , ALEXANDRA ENACHE 1) 1) Discipline of Legal Medicine, Bioethics, Deontology and Medical Law, “Victor Babeş” University of Medicine and Pharmacy, Timişoara, Romania 2) Discipline of Legal Medicine, University of Medicine and Pharmacy of Craiova, Romania 3) Discipline of Anatomy and Legal Medicine, Faculty of Medicine, “Vasile Goldiş” Western University of Arad, Romania 4) Department of Forensic Pathology, Faculty of Medicine, University of Thessaly, Greece Abstract Carbon monoxide (CO) remains an insidious and silent killer due to its physical and chemical properties; its lethal effects are encountered in cases of household accidents, occupational hazards or suicide. Deaths due to CO poisoning were studied retrospectively in the period 2000–2018 at the Institute of Forensic Medicine, Timişoara, Romania. These cases represent 1.75% of all the autopsies and 0.63% of all violent deaths. There have been cases of single deaths and cases with multiple victims – concomitant deaths. The analysis of lethal CO intoxication cases that occurred in different circumstances (incomplete burning with CO accumulation, fires – associated with burns, death in the fountain – due to fossil fuel pump failure, suicide due to exhaust gases) was based on the examination of 298 autopsy files. In this type of poisoning, the forensic examination of the body is marked by the non-specific character of most of the macroscopic and microscopic changes. Although inconstant, these types of changes (e.g., red discoloration of livor mortis) raise the suspicion of death by CO poisoning; the essential contribution to establishing cause of death resides in the determination of carboxyhemoglobin (COHb) concentration by spectroscopy. In all cases, the cerebral and cardio-pulmonary modification and their contribution to the cause of death were studied. Co- morbidities interfere with the cause of death in cases with average COHb concentrations, in the 20–50% range, where CO blood levels alone are not reason enough to explain the onset of death. Keywords: carbon monoxide poisoning, multiple victims, co-morbidities.  Introduction Data published in the last years show that carbon monoxide (CO) intoxication is the number one cause of death due to intoxications in Romania, while in the US is responsible for more than half of the lethal intoxications [1], although the number of deaths decreased with more than 50% [2], from 3500 to 1319 [3–5]. Because of its physical and chemical properties and its non-specific symptomatology CO is called “the silent killer” [6]. CO is a colorless, odorless and tasteless gas that contains 57.13% oxygen and 42.83% carbon (1 kg of CO contains 0.428 kg C and 0.5713 kg O 2 ), with a molecular weight of 28.01. CO is less dense than air, which makes it rise to the upper parts of enclosures. Because of its density, CO easily diffuses through porous walls, even through thin, overheated, iron or cast iron walls of coal or wood-burning stoves [7]. It has high affinity for O 2 , a strong reducing character [8] and 2–6 months half-life in the atmosphere [9]. The toxic properties of CO derive from its capacity to rapidly combine with hemoglobin, thus forming carboxy- hemoglobin (COHb). Due to its incapacity to transport O 2 , COHb diminishes the blood content of O 2 and it diminishes tissular oxygenation because it is a much stable compound than HbO 2 [10]. The effects of CO intoxication on the human body are called oxycarbonism, which can be acute or chronic, depending on the quantity and length of exposure to the gas. The most affected organs are the most sensitive to lack of O 2 (brain, heart), or those with intensive metabolic activity (the liver), where the hypoxic or toxic factor manifests before the onset of clinical symptoms [7]. The external sources of CO are the metallurgical and chemical industry and the household appliances. An often-neglected source of CO is methylene chloride, an aliphatic halogenated hydrocarbon, with sweet taste, resembling chloroform [11]. It is a usual component of paint removers and other solvents [12]. Methylene chloride is absorbed in the lungs, digestive tract and through the skin. Inhaling is, however, the main gate into the human organism [11]. The metabolism of methylene chloride to CO is complex, especially considering the possibility of concomitant exposure to CO [13]. Possible household sources of CO include: clogged chimneys; improperly ventilated fireplaces, gas or wood-burning stoves; non- ventilated, fuel heaters; faulty gas exhaustion pipes; fuel- based engines running in closed spaces; coal barbeques burning in closed spaces; gas water heaters or other improperly ventilated devices [14]. The result of the massive increase in the numbers of cars was a rapid increase of CO emissions, even more so in urban areas R J M E Romanian Journal of Morphology & Embryology http://www.rjme.ro/