Hemodynamic determinants of mortality in human septic shock

Abstract

To assess the relative importance of cardiac versus peripheral vascular failure in patients dying of septic shock, a series of 42 patients with documented septic shock was retrospectively evaluated. Patients were included in the study if serial hemodynamic and metabolic studies had been performed: the first one within 12 hours after onset of septic shock and the last one within 12 hours (median 2 hours; range 0.1 to 12 hours) before death in nonsurvivors. Nonsurvivors were included only if they died in shock. From the patient records the first, highest, and last measured cardiac indexes (CI) (t = 1, t = 2, and t = 3) with concomitant hemodynamic and metabolic variables were obtained. Group I (n = 21) consisted of survivors and group II (n = 21) of nonsurvivors. Group II was divided into three subgroups: group IIa (n = 4) consisted of nonsurvivors with liver cirrhosis, group IIb (n = 9) patients with final CI less than 4 1 X min-1 X m-2, and group IIc (n = 8) patients with final CI greater than 4 1 X min-1 X m-2. At t = 1 no significant differences in hemodynamic variables were found between groups I and II, and all patients, whether surviving or not, were able to increase CI to similar levels. At t = 3 group II showed a marked decrease in mean arterial pressure and systemic vascular resistance index compared with group I (p less than 0.001), whereas CI did not differ significantly. The nonsurvivors showed progressive lactic acidemia. Even group IIb patients showed persistent vasodilation despite a decrease in CI. Our data suggest that many patients in septic shock die as a result of peripheral vascular rather than cardiac failure, since persistent vasodilation, irrespective of CI, was a major hemodynamic determinant in nonsurvivors, of whom 57% maintained a high CI until shortly before death.