Pathologic synergy in cardiovascular and respiratory compensation with cirrhosis and sepsis. A manifestation of a common metabolic defect?

Multivariable physiologic studies of cardiovascular, respiratory, and metabolic functions were performed in 341 patients (884 studies). Eighty patients had cirrhotic liver disease, 64 had sepsis, 87 had nonseptic cariogenic syndromes, and 110 had nonseptic general surgical or traumatic injury. The group with cirrhosis had the highest cardiac index and ejection fraction. When compared with the group with nonseptic surgery or trauma, vascular tone was reduced in the patients with cirrhosis or sepsis and was lowest in patients with both conditions. Ventricular function was good in the groups with cirrhosis or sepsis, due to the additive effect in reducing vascular tone that allowed ejection fraction to increase, but caused the ratio of alveolar ventilation to perfusion (VA/QT) to fall, resulting in a greater perfusion of a decreased pulmonary vascular bed. The falls in vascular tone and VA/QT in patients with cirrhosis or sepsis result from the reduced oxygen consumption that occurs due to metabolic imbalance (B state). This B state seems to reflect a hepatic inability to metabolize aromatic amino acids, so that levels of tyrosine, phenylalanine, and the false neurotransmitter octopamine increase. These mechanisms are pathologically synergistic when sepsis and cirrhosis occur together.