Varying degrees of purposeful activity are possible prior to death (91).
One study documented physical activity in only 21% of sharp-force fatalities (128). Survival times from 5 min to 42 h were seen in some victims, although activity was generally limited (e.g., ascending a staircase prior to collapse ). Another series showed that some physical activity was possible in fatal stab wound cases, based on reliable witness accounts (28). Suicide victims may anticipate a severe injury and can be more physically active than homicide victims, who are frequently taken by surprise (28). Ethanol intoxication does not necessarily affect activity and survival time (128).
Victims are more likely to die immediately when there is a penetrating injury of the heart; however, hemodynamic instability following cardiac injury depends on a number of factors (see Heading 8 and refs. 73 and 128). Other vascular injuries (e.g., aorta) can contribute to shock (73,129). Injury of a coronary artery can precipitate myocardial ischemia (73). The location of the pericardial defect may allow sealing by adjacent mediastinal structures. If the pericardial hole is small, blood is less likely to escape into the pleural cavity. Cardiac tamponade is significant when a volume of 150 to 200 mL is reached (128). A slit-like stab wound, compared with the gaping defect
of a gunshot hole, means the myocardium can contract and narrow the defect (Fig. 34; ref. 28). A hole in the ventricular myocardium less than 1 cm (about 0.5 in.) long can close spontaneously. Small perforations (0.7 to 1 cm; 0.25 to 0.5 in.) of the myocardium, compared with larger holes (up to 2 cm or 0.75 in.), are associated with a longer survival (28). Compared with gunshot wounds, survival time of victims from sharp-force trauma is longer and mortality lower (28,130). In a study of penetrating cardiac wounds, stabbing victims were more likely to reach the hospital (73). Despite a penetrating heart injury, even in the face of multiple injuries, purposeful activity is still possible for a short time (128). One case report described a suicidal stab wound to the chest that resulted in six stab wounds (0.5 to 1 cm or up to about 0.5 in. long) of the anterior left ventricle. Three hundred milliliters of blood collected in the pericar-dial cavity, and the left and right chest cavities contained 320 and 90 mL of blood, respectively. The 44-yr-old male victim was able to wash the knife, changed his bloody clothes, ate lunch in the presence of a relative and died 2 h later (131).
Transection of unilateral carotid and vertebral arteries leads to collapse within seconds, but if blood flow is not completely disrupted on one side, then physical activity is possible for several minutes (28). Exsanguination from a peripheral vein (e.g., great saphenous vein) is a rare event, and survival for several hours is possible (28). A 49-yr-old woman was found hanging after walking 100 m (330 ft) from a car where a knife was found. She had three chest wounds that punctured the lungs and incised her right internal jugular vein (132). Similarly, transection of peripheral arteries can be survived up to several hours (28).
Individuals can survive for hours with other multiple visceral injuries (liver, kidney, lungs), if the heart and great vessels are uninjured (128).
Internal bleeding may not be massive in victims dead at the scene; however, victims surviving longer can have considerable blood loss (128). Blood loss up to 1.5 L can be tolerated without unconsciousness (128). The amount of external blood loss can be estimated by weighing blood-soaked clothing and other linen articles and then reweighing them after washing (26). Evidence (e.g., DNA analysis) from these items takes priority.
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