Intrathoracic pressure variations in an anthropomorphic dummy exposed to air blast, blunt impact, and missiles.

Experiments with an anthropomorphic dummy for blast research demonstrated that pressures recorded in the lung model of the dummy could be correlated to primary air blast effects on the lungs of experimental animals. The results presented here were obtained with a dummy of the type mentioned above, but with the lung model modified to improve geometric similarity to man. Blast experiments were performed in a shock tube, and impact experiments in a special impact machine. Experiments with nonpenetrating missiles were performed with small-caliber firearms and the dummy protected by body armor. Severity indices derived from the blast experiments were related to established criteria for primary lung injury in man. Impacts delivered in the impact machine and by nonpenetrating missiles are compared. Relationships between severity of impact based on experiments with animals and primary lung injury in man are discussed.

Dynamic factors influencing the production of lung injury in rabbits subjected to blunt chest wall impact.

Anesthetized rabbits were exposed to blunt impact on the right chest wall. The controlled impact was delivered with a special machine equipped with a captive piston driven by a freely falling weight. Chest wall deflections were recorded in order to study the effects of magnitude and rate of deformation of the thorax on the resulting lung injury. The ranges of magnitude and rate of deformation corresponded to an inward deflection of the chest wall of about 5-60% of the lateral diameter of the chest, and to a velocity of the chest wall of about 2-20 m/s. Impulses delivered to the chest and intrathoracic pressures were also studied. Severe hemorrhages in the lungs were produced at velocities of the chest wall exceeding about 10 m/s. For velocities of the chest wall below about 5 m/s, lethal injuries were produced without severe hemorrhages in the lungs.