Objective      To study the significance of venoarterial carbon dioxide difference/arterial-venous oxygen difference P(v-a)CO

2

/C(a-v)O

2

ratio in guiding the fluid resuscitation in patients with sev

ere sepsis and septic shock.       Methods      A retrospective study of 40 patients with severe sepsis and septic shock was enrolled in this study. The patients underwent resuscitation through early goal directed therapy (EDGT). The blood lactate and P(v-a)CO

2

/C(a-v)O

2

ratio before resuscitation (0 h)

and at 6 h and 24  h after resuscitation were measured and calculated

and their correlation was statistically analyzed. Blood lactate and P(v-a)CO

2

/C(a-v)O

2

ratio before and after resuscitation were compared

and the effect of P(v-a)CO

2

/C(a-v)O

2

ratio on the prognosis was analyzed.       Results      There was significant correlation between blood lactate and P(v-a)CO

2

/C(a-v)O

2

ratio at 0

6 and 24 h (r=0.737

P0.01; r=0.841

P0.01; r=0.785

P0.01). Compared with those at 0 h

the blood lactate and P(v-a)CO

2

/C(a-v)O

2

ratio at 6 and 24 h were significantly decreased

blood lactate: (5.2±1.9 vs 6.9±1.6 mmol/L

P0.01) and (5.3±2.0  vs 6.9±1.6 mmol/L

P0.01); P(v-a)CO

2

/C(a-v)O

2

ratio: (1.8±0.6 vs 2.5±0.6

P0.01) and (1.9±0.7 vs 2.5±0.6

P0.01). The P(v-a)CO

2

/C(a-v)O

2

ratio of ICU survivors was lower than that of nonsurvivors at 0

6 and 24 h (P0.01).       Conclusion      There is significant correlation between blood lactate and P(v-a)CO

2

/C(a-v)O

2

ratio

and P(v-a)CO

2

/C(a-v)O

2

ratio can reflect the tissue hypoxia and patients’ prognosis

and guide the fluid resuscitation in the patients with severe sepsis and septic shock.