Therapy of shock based on pathophysiology, monitoring, and outcome prediction

High-risk patients who survived general (noncardiac) surgery were observed to have cardiac index (CI) values averaging 4.5 L/min.m2, oxygen delivery (DO2) greater than 600 ml/min.m2, and oxygen consumption (VO2) 170 ml/min.m2 during the first 2 or three days postoperatively. Patients who subsequently died maintained relatively normal CI, DO2, and VO2 values in this period. Values of other variables in survivors and nonsurvivors were not appreciably different. An index based on these observations correctly predicted outcome in 94% in a subsequent prospective study. Two hypotheses: a) that increased flow and oxygen transport represent compensatory physiologic responses to an earlier tissue oxygen debt, and b) that these survivors' values were appropriate therapeutic goals, were tested in prospective randomized clinical trials. The protocol group attained those therapeutic goals. This resulted in significantly reduced mortality and morbidity. Optimal goals were more easily attained with colloids, red cells, and an inotropic agent, dobutamine. Dobutamine was used because, in a prospective crossover clinical trial with dopamine at various doses, dobutamine produced greater increases in flow and flow-related variables. More importantly, it improved tissue perfusion as reflected by greater increases in VO2 and greater reductions in pulmonary and systemic vascular resistance.