Strangulation (cessation of respiratory gas exchange, leading)

Strangulation, cessation of respiratory gas exchange, leading to death, or asphyxia, is observed in many cases and depends on various conditions (see Asphyxia). In everyday life, it is difficult to adhere to such an extensive definition, as it may be incorrectly interpreted and cause misunderstandings. Therefore, in forensic medical practice, the term strangulation in the proper sense is understood to mean only cases of mechanical asphyxia. Obstructions to the entry of air into the lungs may occur throughout the entire respiratory tract. Often the openings of the mouth and nose are intentionally closed by hand, pillow, blanket, etc., in cases of infanticide, and sometimes accidentally, for example, by the mother's body ('overlaying'); in adults, this can occur, for example, when falling face down in mud while intoxicated. Access to air is often blocked by water (drowning), sometimes by loose bodies. Additionally, strangulation occurs from tamponade of the respiratory tract lumen when pieces of food or vomit accidentally enter; foreign bodies (nipples, bread crumbs, rags, newspaper) are introduced mainly for the purpose of infanticide and rarely by one's own hand in suicide. Similarly, the lumen of the respiratory tube can be closed by external pressure; this includes cases of hanging, strangulation by a loop, by hand. Finally, various obstacles to the respiratory excursions of the chest, diaphragm, and lungs lead to strangulation; thus, the chest and abdomen can be compressed by a knee and the weight of a human body in case of murder, then in cave-ins, in a crowd; the lungs - in bilateral traumatic pneumothorax due to air entering the pleural cavities. In determining death from strangulation, the following phenomena observed during autopsy are of essential significance: dark liquid blood in the vascular system, small hemorrhages (ecchymoses), mainly on the connective membranes of the eyes, on the skin in the areas of livor mortis, under the epicardium, more on the posterior surface of the heart, and under the pulmonary pleura (Tardieu spots), as well as congestion of internal organs. When evaluating the presented data, it must be remembered that the dark color is not caused exclusively by asphyxia, but is usual for cadaveric blood containing reduced hemoglobin; the liquid state of blood is also a sign observed in rapid death in general. Therefore, in cases of acute asphyxia, the blood is usually liquid; where asphyxia occurs more prolonged, with agony (incomplete closure of the respiratory openings), clots are present in the vessels. As for the small hemorrhages (ecchymoses), they, as is evident from experiments on animals, form during the convulsive period of asphyxia due to vasomotor spasm and increased blood pressure. Ecchymoses may also occur in other types of death (sepsis, phosphorus poisoning, etc.) when conditions exist for diapedesis phenomena. Congestive hyperemia of internal organs, especially the lungs, is often observed in mechanical forms of strangulation, but not always. Thus, none of the listed phenomena on the corpse has absolute diagnostic significance, but their combination is quite characteristic in general for asphyxia (see). A definite opinion about death from strangulation in the narrow sense can be given only in the presence of certain traces, signs of violence, which are observed in various types of mechanical asphyxia; often the mentioned specific signs may be absent if the openings of the mouth and nose are closed with soft objects. In such cases, on the basis of the picture of asphyxial death alone, it is impossible with certainty either to assert or to deny the possibility of strangulation; the latter can sometimes be established by the circumstances of the case, if they do not arouse doubts.