mitochondrial dysfunction and altered cell death mechanisms, on the development of organ dysfunction are also being unravelled. Insights have been gained into interactions between key organs (such as the kidneys and the gut) and organ–organ crosstalk during sepsis. The important role of the microcirculation in sepsis is increasingly apparent, and new techniques have been developed that make it possible to visualize the microcirculation at the bedside, although these techniques are only research tools at present.
Key points
Although dysfunction can occur in any organ in patients with sepsis, dysfunction in some organs, such as the gastrointestinal tract, is difficult to quantify.Six organ systems for which dysfunction has severe consequences or in which dysfunction is readily detectable (namely ,
the cardiovascular, respiratory , renal, neurological, haematological and hepatic systems) are usually monitored in clinical practice. For each organ, the signs or diagnostic characteristics that are widely used to indicate dysfunction are listed.FiO2, fraction of inspired oxygen; PaO2, arterial partial pressure of oxygen.
Pathophysiology of acute kidney injury in patients with sepsis
Multiple factors can combine to induce cellular damage in the kidneys during sepsis, including altered renal perfusion that leads to cellular hypoxia and the release of various mediators that lead to altered cellular metabolism. Cellular hypoxia might also be aggravated by anaemia, which
can be caused by multiple factors, such as inflammation, blood loss and/or haemodilution. Furthermore, acute kidney injury in sepsis might, in part, be iatrogenic as a consequence of administration of nephrotoxic drugs or iodinated contrast agents that are used for imaging.
Microvascular and cellular alterations in sepsis
Multiple mechanisms are involved in the development of sepsis- related microvascular dysfunction, among which endothelial dysfunction (related partly to circulating host- derived and pathogen- derived mediators as well as to reactive oxygen species (ROS)) and an altered glycocalyx have
major roles. The glycocalyx is a thin layer of glycosaminoglycans that covers the endothelial surface, facilitating the flow of red blood cells and limiting the adhesion of leukocytes and platelets to the endothelium. As the glycocalyx may be substantially altered during sepsis, interactions between the vascular endothelium and circulating cells(for example, leukocytes and platelets) are impaired, and leukocyte rolling and adhesion
to the endothelium may occur. Activation of coagulation and the generation of microthrombi might also participate in sepsis- induced microvascular alterations, as well as alterations in erythrocyte deformability and/or their adhesion to the endothelium. All these phenomena might cause heterogeneity in microvascular blood flow , with a decrease in vascular density and non- perfused capillaries, resulting in an increased diffusion distance for oxygen and in alterations in oxygen extraction. vWF, von Willebrand factor.
Complications associated with hypovolaemia and hypervolaemia in sepsis
Inadequate fluid administration can lead to an increased incidence of complications,mostly due to reduced tissue perfusion, whereas excessive fluid administration is also associated with further complications, mostly due to tissue oedema. CVA ,cerebrovascular accident. Figure adapted from REF. CC BY 4.0.
Interplay between the gut and other organs in sepsis
Various factors can result in gut dysfunction during sepsis, and functional disruption of the gut (for example,gut microbiome dysbiosis) can lead to tissue damage and dysfunction in other organ systems. PAMPs, pathogen- associated molecular patterns.
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