Study objective: We have reported that initial distribution volume of glucose (IDVG) measures the central extracellular fluid volume in the presence of fluid gain or loss without apparent modification of glucose metabolism. We hypothesized that IDVG has a close relationship with intrathoracic blood volume (ITBV). We examined whether IDVG can correlate with ITBV during hemodynamically unstable states early after esophagectomy.
Design: Prospective clinical study.
Setting: General ICU.
Patients or participants: Twelve consecutive hypotensive patients who required volume loading during the first 10 postoperative hours after admission to the ICU.
Interventions: Indexed ITBV (ITBVI) and cardiac index (CI) were measured by single transpulmonary thermodilution technique using 10 mL of cold saline solution. Indexed IDVG (IDVGI) was then determined by the administration of 5 g of glucose and calculated by applying a one-compartment model. Three sets of measurements were performed: immediately after admission to the ICU, during hypotension, and after subsequent volume loading.
Measurements and results: When hypotension developed, stroke volume index (SVI), central venous pressure, and ITBVI were decreased but IDVGI and CI were not. All these variables were increased after volume loading. IDVGI was correlated only slightly with either ITBVI (r2 = 0.23) or SVI (r2 = 0.38) but moderately with CI (r2 = 0.61).
Conclusions: Results does not support that IDVGI can be equivalently used as an alternative measure of ITBVI or SVI, but IDVG may be clinically relevant as a measure of the fluid volume affecting CI even during hemodynamically unstable states after esophagectomy.