Experimental studies on the hemodynamic changes after thoracic impact injury

Hemodynamic changes were monitored in eight dogs subjected to blunt impact (velocity = 19m/s) in the cardiac region. There was a transitory cardiac arrest for 1 to 2 seconds in some animals after trauma. The heart rate decreased markedly at 30 minutes after trauma, and recovered at 4 hours. At 15 minutes after trauma, the cardiac index, stroke volume index, left ventricular stroke work index, and mean artery pressure were much lower than that before trauma (p < 0.05 or p < o.o1). However, the mean pulmonary artery pressure, pulmonary capillary wedge pressure, and central venous pressure at 30 minutes after trauma were higher than that before trauma (p < 0.05). The above changes recovered generally at 8 to 16 hours after trauma. The pathological results showed that superficial spotty or flat hemorrhages and ecchymoses were most common in the injured heart. Severe contusion on the anterior wall of the left or right ventricle was also seen.