Figure 5.
Relationship between oxygen delivery and consumption. O2 delivery is a product of blood flow and arterial O2 content. When O2 delivery decreases below a critical point, O2 consumption is compromised leading to anaerobic metabolism and lactic acidosis. The driving force for O2 into mitochondria is PO2. Increased mitochondrial PO2 can lead to reactive oxygen species formation, while hypoxia can exacerbate pulmonary vasoconstriction. The optimal target range encompasses oxygenation that guarantees an oxygen delivery higher than the critical point so that oxygen consumption is not dependent on delivery, while also avoiding oxygen toxicity. Hb: hemoglobin; SaO2: arterial oxyhemoglobin saturation (Copyright Satyan Lakshminrusimha).