Plasma Volume Expansion Resulting from Intravenous Glucose Tolerance Test

Abstract

Objective. To quantify the degree of plasma volume expansion that occurs during an intravenous glucose tolerance test (IVGTT). Methods. Twenty healthy volunteers (mean age, 28 years) underwent IVGTTs in which 0.3 g/kg of glucose 30% was injected as a bolus over 1 min. Twelve blood samples were collected over 75 min. The plasma glucose and blood hemoglobin concentrations were used to calculate the volume distribution (V d) and the clearance (CL) of both the exogenous glucose and the injected fluid volume. Results. The IVGTT caused a virtually instant plasma volume expansion of 10%. The half-life of the glucose averaged 15 min and the plasma volume expansion 16 min. Correction of the fluid kinetic model for osmotic effects after injection reduced CL for the infused volume by 85%, which illustrates the strength of osmosis in allocating fluid back to the intracellular fluid space. Simulations indicated that plasma volume expansion can be reduced to 60% by increasing the injection time from 1 to 5 min and reducing the glucose load from 0.3 to 0.2 g/kg. Conclusion. A regular IVGTT induced an acute plasma volume expansion that peaked at 10% despite the fact that only 50–80 mL of fluid were administered.

Plasma volume expansion from the intravenous glucose tolerance test before and after hip replacement surgery

“…As seen in several previous studies, the size of body fluid space expanded by fluid ( V ) is remarkably low when being a part of glucose administration. In fact, V is more consistent with the plasma volume (here, 2.7-2.9 L) than with the size of the ECF space [8,10,16]. This is surprising, as the volume of distribution for the exogenous glucose ( V d ) was four times larger.…”

“…The clinician should be aware that injecting hypertonic glucose during an IVGTT induces an abrupt expansion of the plasma volume in all patients. Fortunately, the magnitude in elderly surgical patients is not greater than in younger healthy volunteers [ 8 ], but the hemodynamic consequences are naturally dependent on the cardiac reserves of the subject undergoing the test. For example, the volume load could elicit acute decompensation in patients with worsening heart failure.…”

“…Therefore, the T 1/2 of glucose is apparently a key factor for the duration of the plasma volume expansion following an IVGTT. Previous studies of young healthy volunteers have yielded a T 1/2 for glucose of between 11 minutes and 15 minutes [ 8 , 10 ], while during laparoscopic surgery in females at 40 years of age T 1/2 was 30 minutes [ 16 ]. The patients in the present study were almost 30 years older and had a T 1/2 of 30 minutes even before the surgical stress, which suggests that plasma volume expansion after an IVGTT becomes more long-lasting due to both age and surgery.…”

“…The hypertonicity translocates water from the intracellular (ICF) to the extracellular fluid (ECF) space, where it augments the plasma volume expansion [ 7 ]. The magnitude of the plasma volume expansion resulting from an IVGTT over time has previously been studied in young, healthy volunteers [ 8 ], although the test is usually performed in elderly patients. Moreover, plasma volume kinetics has not been studied in the perioperative setting.…”

Preoperative insulin resistance reduces complications after hip replacement surgery in non-diabetic patients

“…An IVGTT of 0.3 g/kg instantly expands the plasma volume by 10% [ 6 ], which might cause cardiovascular strain in the elderly. Therefore, the dose of glucose was reduced to 0.2 g/kg, and the intravenous injection time was increased from 1 to 4 min, as suggested previously [ 6 ].…”