The initial distribution volume of glucose rather than indocyanine green derived plasma volume is correlated with cardiac output following major surgery

Objectives: To determine whether the initial distribution volume of glucose (IDVG) rather than plasma volume or blood volume is correlated better with cardiac output during the 4 days following major surgery. Design and setting: Prospective clinical investigation in the general intensive care unit of a university hospital. Patients and methods: 31 consecutive patients who underwent radical surgery for esophageal carcinoma were enrolled. Continuous thermodilution cardiac output monitor was placed in the operating room. Indocyanine green (ICG; 25 mg) and glucose (5 g) were administered simultaneously to calculate IDVG and plasma volume determined using the ICG dilution method. Blood volume was also calculated from plasma volume ICG and hematocrit. Those volumes were measured on admission to the ICU and daily on the first 3 postoperative days. The relationships between each volume and cardiac index (CI), and between routine clinical variables and CI were evaluated. Results: IDVG had a linear correlation with CI in the early postoperative days (r = 0.71, n = 124, p < 0.000001). Measurements of neither the plasma volume nor the blood volume yielded a better correlation with CI than did IDVG (r = 0.45, n = 124, p < 0.000001, and r = 0.23, n = 124, p < 0.01, respectively). No correlation was found between pulmonary artery wedge pressure and CI or between central venous pressure and CI. Conclusions: Our results indicate that IDVG rather than intravascular volume is correlated with cardiac output. We suggest that IDVG has potential as an alternative indicator of cardiac preload following major surgery.