Studier av behind armor blunt trauma (BABT)

To study BABT, 30 experimental animals (pigs) were anesthetized and mechanically ventilated. The Swedish armed forces´ assault gun type 4 (Ak 4) was used, firing range was 10 meters using NATO standard 7,62 x 51 mm ammunition; Danish issue M/94. Animals had body armor (Swedish Procurement Agency [FMV] m/94) with a ceramic plate as additional protection, over the right thorax. In a pilot series, 5 animals with a body mass (BM) of about 20 kg were used, while the main series consisted of 25 animals with BM 45 - 80 kg. One of the smaller and 6 of the larger animals were randomised to be controls, and were consequently shot at using blank rounds. Size of body armor matched body size. Ten large animals had body armors stripped of their 14 layers of aramide. In all cases, the projectile was stopped by the body armor. Never the less, three out of 4 small animals died within 30 minutes after impact. There was no mortality among the larger pigs (observation time = 2 hours) having the complete body armor. In the group of animals with the stripped body armor, mortality was 40 %. EEG was registered in 22 animals subjected to live fireing. In 19 of these (3 small, 16 large) there were profound EEG changes, which in an awake human would have been a sign of unconsiousness during about 3 minutes after impact. There were also pathophysiologic effects on lung function and circulation. There were skin lesions, costal fractures, lung hematomas and damaged lung tissue. Control animals showed no changes in EEG, anatomy or physiologic parameters.