Remodeling of soft tissue in the extremities during acute ischemia-reperfusion in the context of acute hemorrhage

Abstract

Histological and morphometric investigation of the soft tissues of the femur in white rats was conducted following acute 2-hour limb ischemia induced by the application of a tourniquet under conditions of acute blood loss. Morphological changes in the soft tissues were examined two hours after the tourniquet application without reperfusion. Tissue examination was carried out at various intervals after the elimination of ischemia: in 2 hours, 1 day, 2 days, 7 days, and 14 days. The early postischemic period model was represented by groups of animals with reperfusion changes at 1 hour, 2 hours, and 1 day after the removal of the tourniquet, while the late postischemic period model comprised groups examined on the 7th day and the 14th day after the removal of the tourniquet.
 Pathological lesions in muscle tissue were evident as edema, structural and integrity impairments in myocytes, and leukocyte infiltration of endo- and perimysium. The lesions of microcirculatory bed were manifested by microarchitectonic damage, stasis, diapedesis hemorrhages, and perivascular cell infiltrates. The most pronounced changes in soft tissues due to reperfusion-ischemic syndrome under acute blood loss conditions were observed on the first day. During this period, the average diameter of muscle fibers ((43.66±0.41) μm) exceeded the corresponding control group indicator ((40.63±0.24) μm) by 6.94% (P < 0.01). Subsequently, there was a gradual normalization of indicators, with the diameter on the 14th day ((40.83±0.36) μm) not significantly differing from the control (P > 0.05).
 The revealed patterns can be used to develop new approaches and methods for the correction of structural and functional disorders of soft tissues in lower extremities by different types of acute ischemic trauma under conditions of acute blood loss.