Cardiac output in early phase of blast injury in rabbits.

Abstract

Changes in cardiac output measured by the direct Fick method were studied in rabbits which had been exposed to high explosive shock waves in a detonation chamber. The maximum reflection overpressure in the shock waves ranged between 3.5 and 11 atm. for the different weights of charge used. In all exposed animals there was a decrease in cardiac output already 5 minutes after the detonation. The degree of reduction of the output of the heart is directly proportional to the weight of charge used, i.e. of the force of the detonation. The cardiac output and the lung hemorrhages seem to be two parallel effects of the pressure of the shock wave with no mutual interference between the two. The cause of the reduction seem to be complex, but the direct action of the shock wave on the heart is supposed to play a significant role. The bradycardia existing during the 1st minute after the detonation was found to be of no importance for the reduction of the output of the heart.