Intravital microscopy of the microcirculation in man during and after experimentally controlled ischemia

In man, using a skin tube chamber technique, microvascular reactions during and after complete experimental ischemia was studied by intravital microscopy. During 1 and 2 hour ischemia the trapped blood cells did not adhere to each other or to the vascular walls except for RBCs which formed rouleaux. Reflow after 1 and 2 hour ischemia was rapid with a hyperemic reaction and a transient increase in WBC stickiness. Thus, a mild and reversible inflammatory reaction was provoked by the short ischemic insult. During 6 hour ischemia most of the blood cells maintained their integrity. However, in a few vessels the RCSs formed homogeneous masses indicating hemolysis of some of the RBCs. There was also marked diapedesis of RBCs and increased WBC stickiness, but the platelets did not react to form thrombi. After the 6 hour ischemia reflow occurred in all vessels and the homogeneous masses seemed to cause only a temporary hindrance to reflow. The final outcome of the 6 hour ischemic insult was uncertain since in one of the two experiments there was a complete circulatory standstill 24 hours after the ischemia while in the other there was an almost normal blood flow.