In septic shock, what happens to the delivery of oxygen to the tissues?

In septic shock, the delivery of oxygen to the tissues typically becomes compromised due to a combination of factors associated with the underlying physiological changes of sepsis. While the initial thought may be that oxygen delivery could be increased due to elevated cardiac output, the reality is more complex.

In septic shock, systemic inflammatory response leads to widespread vasodilation and increased capillary permeability. This can cause a relative hypovolemia even in the presence of increased cardiac output, often leading to poor tissue perfusion despite apparently adequate or even elevated heart rates and stroke volumes. Additionally, tissues may also experience reduced oxygen utilization due to cellular dysfunction, which occurs when cells are unable to properly utilize oxygen for metabolism, known as mitochondrial dysfunction.

The interplay of these factors usually results in decreased effective oxygen delivery to tissues, even if you consider the theoretical increases in blood flow from elevated cardiac output. Hence, the correct understanding is that oxygen delivery to tissues is compromised, leading to increased risk of organ dysfunction due to insufficient oxygenation.