Lack of oxygen supply dependency in patients with severe sepsis. A study of oxygen delivery increased by military antishock trouser and dobutamine.

BACKGROUND

During severe sepsis, the existence of a pathologic oxygen supply dependency remains controversial.

STUDY OBJECTIVE

To evaluate the relationship between oxygen delivery (DO2) and oxygen consumption (VO2) during severe sepsis and to compare, in this respect, survivors and nonsurvivors and patients with normal or increased concentration of plasma lactate.

STUDY DESIGN

Cohort analytic study.

SETTING

Three European ICUs in university hospitals.

PATIENTS

Seventeen mechanically ventilated patients with severe sepsis (six with high blood lactate levels) studied within the first day of diagnosis.

INTERVENTIONS AND MEASUREMENTS

Pulmonary elimination of carbon dioxide, or carbon dioxide production (VCO2) and VO2 were measured by indirect calorimetry before and after two interventions designed to increase DO2 (calculated from the Fick equation): inflation of a military antishock trouser (MAST) and infusion of dobutamine.

RESULTS

During MAST inflation, DO2 increased by 19% in patients with a normal concentration of plasma lactate (p < 0.01), but remained unchanged in patients with high lactate levels. During dobutamine infusion, DO2 increased in both groups by 16% (p < 0.01) and 20% (p < 0.05), respectively. In both groups, we found that the VO2 and VCO2 were not affected by either the MAST or the dobutamine-induced increase in DO2. There was no difference between survivors and nonsurvivors.

CONCLUSION

There was no evidence of a pathologic oxygen supply dependency in patients with severe sepsis, even in those who had an elevated concentration of plasma lactate and in those who ultimately died. These results do not favor the conclusion that maximizing DO2 is a primary therapeutic objective in such patients.