Optimal oxygen delivery in critically ill patients.

Standard hemodynamic support in septic shock is to increase pulmonary capillary wedge pressure to above 15 mmHg by volume replacement and to give inotropic support if the mean arterial pressure (MAP) is not adequate. In an attempt to decrease mortality in critically ill patients, oxygen delivery (DO2) was increased by switching inotropic support from dobutamine alone or in combination with norepinephrine to dopamine alone, or by adding dopexamine, prostacyclin, or hypertonic saline to the treatment. DO2 increased significantly in all patients, but the increase in DO2 was accompanied by only a 10% increase in oxygen consumption (VO2). The increase in VO2 was similar in survivors and nonsurvivors and in patients with and without septic shock. The results indicate that if adequate volume and inotropic support is provided for critically ill patients, the detectable oxygen debt is small and has little effect on patient outcome. When DO2 is adequate, factors other than a tissue oxygen deficit seem to determine patient outcome.