Mechanism of Fatal Chest Injury by Baseball Impact

This study describes the development of an animal model to characterize the mechanism of death by baseball impact of the chest in children. Sixteen anesthetized animals were subjected to midsternal, blunt chest trauma by a baseball accelerated to 95 mph (42.8 m/s). At this speed, death occurred by traumatic arrhythmia and apnea. The animals were divided into two groups: 10 were breathing spontaneously and six underwent controlled ventilation. All animals developing ventricular fibrillation as the initial arrhythmia died regardless of ventilatory status. Survival related to the use of ventilatory support. Four of the six (66.7%) ventilated animals survived, as opposed to two of 10 (20.0%) animals breathing spontaneously (χ2 = p < 0.06). Necropsy revealed minor myocardial contusions but none sufficient to cause death. The study has generated a reproducible model of pediatric cardiac arrest induced by high-speed baseball impact and emphasizes the role of ventricular fibrillation and adequate ventilatory support.