The effects of increasing oxygen delivery (DO2) on oxygen consumption (VO2) in eight patients with septic shock and five patients with hypovolemic shock were studied during fluid resuscitation. In the septic shock group, DO2 increased from 315 +/- 29 to 424 +/- 25 ml/min/m2 (p less than 0.01) and VO2 increased from 134 +/- 8 to 151 +/- 7 ml/min/m2 (p less than 0.01). In the hypovolemic shock group, DO2 increased from 239 +/- 26 to 386 +/- 48 ml/min/m2 (p less than 0.01) and VO2 increased from 96 +/- 9 to 135 +/- 6 ml/min/m2 (p less than 0.01). There was no significant difference in either the increase in DO2 or VO2 between the septic shock and hypovolemic shock patients. We conclude that increasing DO2 by fluid resuscitation increases VO2 during both hypovolemic and septic shock.