The plasma and ISF are nearly identical except for the protein concentration and its attendant Gibbs–Donnan effect. The main fluid compartments are not these, but the intracellular fluid, interstitial fluid (ISF), and plasma, which can be obtained from the volumes of distribution of these markers. The plasma volume can be found using Evan’s blue dye as a marker, and. The extracellular volume can be determined by inulin as a marker, and it averages 20% of body weight. Total body water is marked by deuterium oxide and averages around 60% of body weight. This chapter describes the indicator dilution method for determining the volume of distribution of otherwise inaccessible fluid compartments. Moreover, the BIS, estimating the volume restoration of the different body compartments, may be helpful in evaluating the effectiveness of the pharmacological treatment.
The BIS, a simple, reliable, non invasive and cost effective methodical approach, estimating the distribution of body fluids, offers new possibility of the management of the hypertensive disease, to establish a more appropriate antihypertensive treatment. Our data confirm that the blood pressure increases are associated to TBW, and caused mainly by ICW increases. This difference was proportional to the difference of mean blood pressure values, reaching significance only as regards the stage II hypertensive subgroup (p < 0.03).
We found higher ICW values in hypertensive compared to normotensive subjects. They underwent anthropometric measurements, then extracellular (ECW) and intracellular water (ICW) were assessed using BIS.īoth mean weight and BMI of hypertensive patients resulted significantly higher than of the control group (p < 0.05). hypertensive patients (14 females, 14 males, mean age 47 +/- 5) and a sex- and age-matched control group of 37 healthy subjects (17 females and 20 males, mean age 45 +/- 8). We have estimated the compartmental distribution of body fluids by means of the Bioimpedance Spectroscopy (BIS) analysis in a hypertensive cohort compared to control subjects. There is a correlation between the fluid and ionic homeostasis and blood pressure but it is not known if these body fluid changes represent the cause or rather the effect of the blood pressure rise. It is found that changes in plasma fluid volume and composition are transferred to the ISF and from there to the intracellular fluid. The renal system accomplishes its task of regulating body fluid compartment size and composition by operating solely on the plasma. The presence of anionic proteins in the plasma that cannot equilibrate across the capillary wall sets up a slightly unequal concentration of diffusible ions across the capillary. The volumes of the various fluid compartments vary with age, gender, and body composition. The intracellular volume is the TBW minus the ECF, and the ISF volume is calculated as the ECF minus the plasma. These volumes can be calculated from the volume of distribution of marker substances that distribute themselves according to the total body water (TBW), extracellular fluid (ECF), or the plasma. In a normal young adult male, these comprise about 40%, 15%, and 5% of body weight, respectively. The body fluids consist of three major compartments that include the intracellular fluid, the interstitial fluid (ISF), and the plasma. The overall function of the renal system is to regulate the volume and composition of body fluids.