Septic Shock Question

[jenndavis]

My class is preparing for a SIM Lab dealing with Septic Shock and Multiple Organ Dysfunction. I think I'm on the right track for a question, but I'm not sure.....

The Question:

Explain why myocardial depression is almost always present in a patient with septic shock despite an initial rise in cardiac output.

My Answer:

In septic shock there is a release of vasoactive substances due to the inflammatory response. This leads to vasodilation. This vasodilation decreases systemic vascular resistance and leads to a high cardiac output because of the decrease in peripheral resistance. Despite the elevated CO, abnormalities exist in oxygen extraction in the tissues. As shock continues, compensatory mechanisms, which were previously maintaining adequate perfusion of organs, become ineffective. There will be a decrease in coronary perfusion which leads to a decrease is CO.

Am I on the right track? Thank you for your help.

[MunoRN, RN]

That's actually a pretty impressive answer given the general lack of understanding regarding hemodynamic and cardiac effects of sepsis. While I can't begin to guess what your instructors are looking for, a couple of things to consider; we still don't know the exact mechanism of Sepsis that produces myocardial depression, although the best guess seems to be that it is due to the negative inotropic effects of various cytokines (mainly TNF alpha), and actually, global ischemia isn't considered to be a strong contributor: Sepsis and the Heart

Negative inotropic effects of cytokines:Negative inotropic effects of cytokines on the heart... [science. 1992] - PubMed - NCBI

The Role of Inflammatory Mediators in the Failing Heart - Google Books