Dead spot
As dead spots (medical- latin : Livores , Dead spots) is normally red-violet to blue-gray discoloration of the skin on the dependent parts of the body referred to, which occurs after death. The first death spots appear about 20 to 30 minutes after the cardiac arrest. They are therefore the earliest sure sign of death to appear .
Emergence
Livores arise from the gravitational sinking of the blood within the vessels of a corpse . This process is known as hypostasis and affects not only the blood, but all body fluids. Dead spots are the result of the hypostasis-induced excess of blood in the skin vessels. When a corpse is lying on its back , they can therefore be found on the back . If the body remains in an upright position after death, e.g. B. in death by hanging , then they can be found on the legs and hands. They do not develop in areas of the body where external pressure is exerted on the skin. For example, the resting areas or the areas with tight-fitting clothing are free of livores. Furthermore, the nipples and areola are spared.
First of all, the dead spots are recognizable as blotchy discolorations of the skin, which then become more intense in color and flow together (confluence). In the case of particularly intense dead spots, such as those that sometimes occur in the case of death from suffocation or drug deaths, there may be a few millimeter, dark blue-violet bleeding of the dead spots ( vibices ). These arise as a result of ruptures in the skin capillaries. Vibices therefore only occur in the area of the dead spots. If vibices are found in non-discolored areas, this suggests a postmortem change in the position with a shift in the dead spots.
Expression
In the deceased who remain in the supine position after death, the dead spots usually extend from the rear trunk wall to roughly the anterior axillary lines. Shoulder u. The buttocks area as well as the calf arches and heels are then often spared from the formation of the dead spots because the contact pressure is greater than the gravitational pressure of the sinking blood, so that the capillaries cannot fill. With severe blood loss (after external and internal bleeding ) or with chronic anemia , only sparse death spots are found.
Movability
The dead spots can be completely “relocated” up to six hours after death: If the position of the corpse is changed, the dead spots also move under the influence of gravity . If the corpse is turned over within a period of between six and twelve hours after death, the corpse stains can only be partially repositioned and can therefore be found both above and below.
Push-away
For a period of up to 36 hours, the Livores can still be pushed away at least partially under strong finger pressure, as part of the blood is still mobile within the veins and in them (pressure on the corpse stain, and the skin under the pressure point looks light again). Later on, so much serum has escaped from the vascular system that the blood has "thickened" and the dead spots can no longer be pushed away. But even beyond that, Livores can usually be pushed away at least partially at certain points, for example by applying forceful pressure with the back of a pair of tweezers.
colour
The initially reddish color of the blood changes into a bluish-livid hue as a result of the oxygen consumption in the agony , which is considered normal for dead spots. However, when a corpse is brought into a cold environment, the color of the dead spots changes to bright red over time; the same color is found in death from hypothermia. The most important differential diagnosis for bright red dead spots is carbon monoxide (CO) poisoning . In the case of hydrogen cyanide poisoning, light red dead spots can also occur, but their color is not as intense as in exposure to cold or CO poisoning. The color quality under the fingernails and toenails as well as on the palms of the hands and soles of the feet is an important criterion for differentiating the genesis of bright red dead spots during an inquest: While the dead spots there also appear bright red in the case of CO intoxication, they are usually blue-violet when exposed to cold. The cause of the change in color is the cold-induced shift to the left of the oxygen binding curve of hemoglobin : the cold makes the binding of oxygen to hemoglobin easier and makes it more difficult to release it to the tissue. Oxygen diffuses from the ambient air through the skin of the hypostatic areas and binds to hemoglobin there. The color qualities of light red dead spots after exposure to cold or in the event of CO intoxication are very similar and the spectral remission curves hardly differ. A gray-brown color occurs in the case of poisoning with nitrates or nitrites, which lead to an oxidation of the central iron atom in hemoglobin ( methemoglobin ). Hydrogen sulfide poisoning leads to the formation of sulfhemoglobin , which causes the dead spots to turn green.
literature
- M. Bohnert, W. Weinmann, S. Pollak: Spectrophotometric evaluation of postmortem lividity. In: Forensic Sci Int. 99, 1999, pp. 149-158.
- M. Bohnert, K. Schulz, L. Belenkaia, AW Liehr: Reoxygenation of hemoglobin in livores after postmortem exposure to a cold environment. In: Int J Legal Med. 122, 2008, pp. 91-96.
- L. Belenki, V. Sterzik, K. Schulz, M. Bohnert: Analyzing reflectance spectra of human skin in legal medicine. In: Journal Biomedical Optics. 18 (1), 2013 Jan, p. 17004.
- L. Belenki, V. Sterzik, M. Bohnert: Similarity analysis of spectra obtained via reflectance spectrometry in legal medicine. In: Journal of laboratory automation. Volume 19, Number 1, February 2014, pp. 110-118. doi: 10.1177 / 2211068213496089 , PMID 23897013 .
- B. Brinkmann, B. Madea (Ed.): Handbook for judicial medicine . Springer, Berlin / Heidelberg 2004.
- U. Hellerich, M. Bohnert, S. Pollak: Modification of the hypostasis findings in the nipple region. In: Arch Kriminol. 207, 2001, pp. 162-169.
- C. Henssge, B. Knight, T. Krompecher, B. Madea, L. Nokes: The estimation of the time since death in the early postmortem period . Arnold, London / Sydney / Auckland 1995.
- FJ Holzer: About peculiarities when the dead spots turn red. In: Z Medizinalbeamt. 2, 1934, pp. 65-72.
