Cardiovascular changes in sepsis.

The hyperdynamic circulation characteristic of severe sepsis is not likely due to peripheral arteriovenous shunts since in skeletal muscle, at least, capillary blood flow is increased and varies directly with cardiac index. The finding that flow is normal in some septic patients who are severely ill and close to death suggests that blood flow can no longer be considered the critical factor explaining the death of the septic patient. Clearly, the commonly accepted sequence of low blood flow, tissue hypoxia, lactacidosis, and death does not apply to all patients dying from shock. The hyperdynamic circulatory state and the metabolic changes associated with severe sepsis may be related. Skeletal muscle capillary blood flow was increased in fasting normal subjects and septic postoperative patients, both of whom were catabolic. Therefore, elevated blood flow, which is characteristic of severe sepsis, may be a response to the catabolism of body protein required for energy production. If this concept of sepsis is accepted, it follows that treatment which heretofore has been aimed at increasing blood flow and blood pressure should be redirected to therapy which provides energy substrates and alters hormonal patterns to favor anabolism.