engleski

Carboxyhemoglobin as an indicator of entrance gunshot wound

The handling of gunshot wound cases inevitably encompasses determination of direction of fire, i.e. distinguishing entrance from exit wound, as well as the range of fire. In many cases, features of the wounds are quite typical, enabling forensic medicine expert to reliably answer both of those questions. On the contrary, appearance of the gunshot wound can be unusual, thus challenging the knowledge and experience of the examiner. Apart from recognizing particular wound type on the basis of its gross appearance at the autopsy, there are many additional methods developed to strengthen the conclusion on the type of wound. Microscopic searching for powder particle remains and chemical methods which aim to detect the elements in the primer are among of them. The presence of cherry-red discoloration of the blood and muscles surrounding the entrance wound is mentioned by many standard textbooks in the field. This observation is usually listed without the quoting of relevant reference data. Starting from the hypothesis that contact and possibly close-range discharges may cause entering of propellant gases into the wound in amounts sufficient to cause production of carboxyhemoglobin (CO-Hb) and/or carboxymyoglobin around the entry site, we examined practical applicability of that phenomenon. We examined 15 consecutive cases of firearm fatalities. Shots were fired from contact or near contact range. CO-Hb level was determined from the blood samples taken from the entrance and exit wound. In non-penetrating wounds, the latter sample was taken where the missile was found. Blood from femoral vessels was also taken for CO-Hb determination, representing the control samples. There were 13 cases of suicide and 2 homicides, 11 contact and 4 near contact wounds. Pistol was the weapon of discharge in 12 cases, followed by revolver (2 cases) and shotgun (1 case). CO-Hb at entrance wound was found positive in 14 out of 15 (93%) cases, values ranging from 2 to 20%. As opposed to that, only 5 of 15 (33%) cases were positive for CO-Hb at exit wound or bullet site. In that “exit-positive” group, the level of CO-Hb was lower than at the entrance site in 4 cases. All the control samples were negative. Above results confirmed that blood sampling for CO-Hb in cases of gunshot injuries is simple, quick and easy-to-read ancillary method in determining the entrance wound. Additionaly, knowing the chemical stability of CO-Hb, we anticipate that it could be of particular usefulness in decomposed corpses, where appearance of the wound is usually altered, thus making the interpretation difficult.

gunshot wounds; entrance vs. exit wound; range of fire; carboxyhemo

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