Red blood cell accumulation in a rat model of pulmonary ischemia/reperfusion injury

Red blood cell (RBC) accumulation in lung tissue during ischemia/reperfusion has not been studied extensively. A warm lung ischemia/reperfusion-injury model was developed to determine RBC trapping.

Twenty-four rats were randomized into 5 groups. In 4 groups, the left lung was submitted to 20 minutes of warm ischemia followed by reperfusion for 3, 10, 30 and 60 minutes. Subsequently, both lungs were flushed. Afterwards the heart-lung block was removed and fixed endoluminally. The fifth group was the sham group, in which lungs were flushed after 20 minutes of perfusion without induction of ischemia. RBC were counted in the hilar sectional plane and expressed in area%.

In the left reperfused ischemic lung, already 3 minutes after reperfusion, a significant accumulation of RBC was found in the capillaries. This accumulation was accompanied by a significant vascular congestion of these vessels. After in vivo perfusion, almost all RBC were flushed out the blood vessels of the non-ischemic lung (area%=0.082). In ischemic reperfused lungs, capillaries were densely packed with RBC. Significantly more RBC were counted after 3 (area%=1.572; P=0.002) and 10 minutes (area%=1.240; P=0.011) of reperfusion compared to the sham group. After 30 (area%=0.929; P=0.054) and 60 minutes (area%=0.435; P=0.404) no significant increase in RBC was observed compared to the sham group. In the right non-ischemic lungs, no differences in RBC accumulation were observed between the sham group and ischemia-reperfusion groups.

After warm ischemia/reperfusion, a significant early increase in accumulation of RBC was observed.