TITLE: THE INITIAL DISTRIBUTION VOLUME OF GLUCOSE RATHER THAN PLASMA VOLUME AFFECTS CARDIAC OUTPUT FOLLOWING MAJOR SURGERY

AUTHORS: Hironori Ishihara, MD, Akiko Suzuki, MD, Hirobumi Okawa, MD, Toshihito Tsubo, MD, Akitomo Matsuki, MD
AFFILIATION: University of Hirosaki School of Medicine, Hirosaki, Japan.

Although blood volume or plasma volume determined by the indocyanine green (ICG) dilution method (PV-ICG) has become clinically available, fluid therapy is aimed to maintain cardiac output (CO) rather than maintain the total intravascular volume. The initial distribution volume of glucose (IDVG) has been found to consistently indicate the extracellular fluid volume of highly perfused tissues including heart and lungs in various pathologic conditions^{1, 2)} without significant effects of glucose metabolism. As the IDVG can be predicted simply and rapidly in the critically ill³⁾, the IDVG would be useful as a determinant of cardiac preload if the IDVG has a close linear correlation with CO. The present study was designed to test whether the IDVG rather than the PV-ICG affects CO during the early postoperative period following major surgery.
METHODS: Seventeen consecutive patients (age: 60.9±8.0 (SD) years, body weight: 61.3±10.9kg) following the radical operation for esophageal cancer were studied daily during the first three post-operative days (POD). No patient had previous history of cardiac diseases. The two volumes were calculated utilizing a one-compartment model by simultaneous administration of glucose 5g and ICG 25 mg as described previously¹⁾. Data were analyzed by ANOVA followed by New- man Keuls test. Regression analysis was also performed. A pvalue <0.05 identified statistically significant difference.
RESULTS: The IDVG, the PV-ICG and CO after surgery on the operative day were 6.16±1.26 (SD) L2.60±0.52 L and 5.4±1.3 L/ min, respectively. The two volumes increased on the 2nd and 3rd PODs compared with the operative day (p<0.05). Pulmonary artery wedge pressure (PAWP) remained less than 15 mmHg and statistically unchanged throughout the study period. CO increased on the 3rd POD compared with the operative day (p<0.05). Although the IDVG correlated linearly with the PV- ICG (r=0.72, n=68, p<0.001), CO correlated better with the IDVG (r=0.80) compared with the PV-ICG (r=0.63). No correlation was found between PAWP and CO (r=0.10).
CONCLUSIONS: Results indicate that the IDVG rather than the PV-ICG affects CO, suggesting that the IDVG has potential of a determinant of cardiac preload during the early postoperative period, even though intravenously administered glucose rapidly distributes into the extravascular space.
REFERENCES:

1.) Burns 1998; 24:525-531,

2.) Br J Anaesth 1998; 81: 193-197,

3.) Br J Clin Pharmacol 1999; 47: 361-364.