The Continuous Monitoring of Mixed Venous Oxygen Saturation for the Estimation of Cardiac Output Changes for Liver Transplantation in Dogs

Kang, Ki Chul; Lee, Kook Hyun; Oh, Yong Seok; Ham, Byung Moon; Kim, Kwang Woo

Abstract

BACKGROUND: In the management of liver transplantation, massive blood loss, interruption of venous retum to the heart, sudden infusion of acidic, cold and hyperkalemic blood from the graft, and uses of inotropic and vasoactive agents make cardiac output (CO) change unpredictably. We tried to find convenient method to estimate the change of CO by mixed venous oxygen saturation (SvO2) which can be monitored by pulmonary artery catheterization with fiberoptic oximeter using a spectrophotometer, By adapting the equation of oxygen transport and oxygen consumption(VO2), the equation CO=V/O2(Hbx0.134)x1/(SaO2-SvO2) can be obtained. If we assume the VO2 and hemoglobin concentration is constant and hypoxemia is excluded, CO might be proportional to I/(100-Sv O2). METHOD: For the management of orthotopic liver transplantations in 5 mongrel dogs, we continuously monitored Sv O2 with fiberoptic pulmonary catheter and intermittently measured the CO by thermodilution method according to operative phases. The Pearsons correlation coefficients between CO and mean arterial pressure, CO and S vO. and CO and 1/(100 SvO2) were measured in each dog. RESULT: The correlation coefficients between CO and 1/(100 SvO2) are raging from 0.74 to 0.98 with a corrected mean of 0.847 and significant in all dogs (p<0.05), and the correlation coefficients between CO and SvO2 are ranging from 0.67 to 0.96 with a corrected means of 0.786 and significant in 4 of 5 dogs.
CONCLUSIONS
For the management of liver transplantation, the continuous monitoring of mixed venous oxygen saturation by a fiberoptic pulmonary catheter is helpful to detect changes of cardiac output.