Venous admixture in human septic shock. Comparative effects of blood volume expansion, dopamine infusion and isoproterenol infusion on mismatching of ventilation and pulmonary blood flow in peritonitis

Abstract

A hemodynamic study with blood gas analysis was performed so we could observe changes induced by blood volume expansion, dopamine infusion and isoproterenol infusion in 20 adult patients suffering from peritonitis complicated with septic shock and acute respiratory failure. Blood volume expansion increased cardiac index (from 2.6 ± 1.21/min/m2 to 3.4 ± 1.3 l/min/m2; p<0.001), but also enhanced venous admixture (Q̇S/Q̇T) from 27 ± 14% to 36 ± 13%; p<0.01). Dopamine infusion increased cardiac index (from 2.6 ± 0.9 l/min/m2 to 3.4 1 l/min/m2; p<0.001), but also enhanced venous admixture (from 25 ± 11% to 31 12%, p<0.001). Isoproterenol infusion increased cardiac index (from 2.6 ± 0.9 l/min/m2 to 3.6 ± 1.1 l/min/m2; p<0.001), but also enhanced venous admixture (from 27 ± 12% to 33 ± 11%; p<0.001). This worsening in mismatching of ventilation and blood flow is correlated with the enhancement pulmonary blood flow obtained by these three therapeutic procedures.