This book draws a pathway from metabolic assessment and nutrition support to advances in renal replacement therapy and organ support in critical care, underling the specific clinical aspect and focusing on medical clinical management in critical care. Metabolic alterations in critically ill patients have been studied for many years. Despite everything, the heterogeneity of critically ill patients, the duration and variable severity of the acute phase of the disease and the numerous confounding factors have hindered progress in this field. A cornerstone of metabolic care is nutrition, that is an essential part of the care for critically ill patients, although the optimal feeding strategy for patients in the intensive care unit is still debated and often remains a challenge for the intensive care team in clinical practice. In addition, acute loss of renal function interferes with the metabolism of all macronutrients, responsible for pro-inflammatory, pro-oxidative and hyper-catabolic situations. The physiological and biological modifications related to acute renal failure in critically ill patients, including the current use of continuous renal replacement therapies, have dramatically changed the type and importance of the metabolic and nutrition disturbances observed during treatment of renal failure. This book - addressed to healthcare providers working in intensive care units -  aims to provide a comprehensive synthesis and interpretation of the adult critical care nutrition and critical care nephrology literature, 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.