This book describes deleterious inter-organ crosstalk and its mechanistic concepts, underlying the specific clinical aspect and focusing on medical clinical management in critical care. Homeostasis and health of multicellular organisms with multiple organs depends on inter-organ communication. Tissue injury in one organ disturbs this homeostasis and can lead to disease in multiple organs, or multi-organ failure. Many routes of inter-organ crosstalk during homeostasis are relatively well known, but inter-organ crosstalk in disease still lacks understanding. Particularly, how tissue injury in one organ can drive injury at remote sites and trigger multi-organ failure with high mortality is poorly understood. Mechanistically, inter-organ crosstalk after tissue injury could involve soluble mediators and their target receptors, cellular mediators, in particular immune cells, as well as newly identified neuro-immune connections. The book - addressed to healthcare providers working in intensive care units - aims to provide a comprehensive synthesis and interpretation of organ crosstalk, with a particular focus on continuing practice gaps and areas with new data, to assist clinicians in making practical, yet evidence-based decisions regarding nutrition management during the different stages of critical illness.