Intrathoracic microvascular circulation in haemorrhagically shocked rats. Studies by fluorescence techniques

The microvascular circulation in the heart, lung and thymus was studied by fluorometry in 32 haemorrhagically shocked rats. Exsanguination to a blood pressure of 35 mmHg for 180 min did not result in any reduction of this circulation in the heart or lung, but in the thymus it was reduced by 52%. Retransfusion of shed blood caused no change in cardiac microcirculation, whereas the microcirculation in the thymus was increased by 59%. In the lungs a heterogeneous fluorescence pattern was observed after retransfusion, with large dark areas alternating with normal fluorescent ones and even some small intensively fluorescent areas. After retransfusion, maldistribution of blood flow seems to be a phenomenon of haemorrhagic shock in the lungs.