[Hepatic venous and mixed venous O2 saturation during catecholamine therapy in patients with septic shock]

Mixed venous O2-saturation (SvO2) reflects the ratio of global O2 supply to O2 consumption. However, in septic shock, there may be alterations in the ratio of regional O2 supply to O2 consumption, particularly in the splanchnic region. The aim of the study was therefore to investigate the relation between SvO2 and hepaticovenous O2-saturation (ShvO2) in septic shock with different catecholamine regimens. METHOD. Following approval of the ethics commission at our hospital, SvO2 and ShvO2 were measured simultaneously in 29 patients (7.5-F pulmonary arterial catheter). RESULTS. SvO2 and ShvO2 showed a considerable inter-individual difference with values between 1.3 and 36.9% and a mean of 14.7 +/- 9.3%. Alterations of ShvO2 were only tendentially reflected in alterations of the SvO2. Under different catecholamines SvO2 and ShvO2 showed the same changes but varying in extent (Table 1; Fig. 2). After switching the catecholamine therapy from dobutamine to epinephrine, SvO2 decreased only from 76.7 +/- 3.6 to 76.1 +/- 2.3 but ShvO2 from 61.4 +/- 8.1 to 54.2 +/- 10.3%. When the therapy was switched from dobutamine to norepinephrine, SvO2 decreased from 74.8 +/- 4.9% to 68.5 +/- 4.8%, ShvO2 decreased from 61.9 +/- 12.9% to 49.2 +/- 12.8%. When dopamine was added to norepinephrine, SvO2 increased from 68.6 +/- 4.3% to 73.6 +/- 4.4%, ShvO2 increased from 52.6 +/- 12.7% to 63.7 +/- 9.8%. When dopexamine was added to dobutamine, SvO2 increased from 74.6 +/- 4.5% to 76.9 +/- 2.5%, while ShvO2 increased from 57.6 +/- 11.5% to 58.8 +/- 13.4%. DISCUSSION AND CONCLUSION. The results presented show that SvO2 does not provide sufficient information about the venous O2 saturation of the splanchnic region. The intraindividually variable differences between SvO2 and ShvO2 during therapeutic interventions demonstrate that a selective alteration of blood supply to or O2 consumption of the splanchnic region has taken place, which is insufficiently reflected by the SvO2.