The textbook "Occult Hypoperfusion Following Cardiac Surgery: Markers and Outcome" offers a comprehensive analysis of the risks associated with inadequate perioperative oxygen supply in patients after heart surgeries. It explains how the imbalance between oxygen delivery and consumption can lead to a series of events culminating in multiple organ failure (MODS). This not only affects the length of stay in the intensive care unit or hospital but also has implications for associated healthcare costs and resource consumption. The book critiques the conventional practice of considering the normalization of vital signs as the endpoint of resuscitation, highlighting that this may not accurately reflect actual tissue perfusion. Alternative markers such as central venous oxygen saturation and lactate levels are presented, which can be used in various clinical situations to assess perfusion adequacy. The combination of these markers is discussed as a promising tool for evaluating the incidence of occult hypoperfusion and the adequacy of resuscitation.