Regulation of fluid and electrolyte balance

An Investigation into Equations for Estimating Water Requirements and the Development of New Equations for Predicting Total Water Intake

“…Osmosis is the movement of water across a semipermeable membrane. Movement of water occurs from an area of low to high solute concentration (Louden, 2009). However, not all solutes are alike in their water-attracting ability (Grandjean et al, 2004;Guyton & Hall, 2006).…”

“…An isotonic solution has an osmolarity of 290milliosmoles/L (mOsm/L) (Whitmire). Thus, a cell placed in a hypertonic solution will shrink whereas a cell placed in a hypotonic solution will swell (Louden, 2009). …”

“…0.9% saline is isotonic to plasma, is the main ECF cation, and has a significant effect on effective osmolality. For this reason, a high level of sodium in the plasma is the main cause of the shifting of water out of the ICF to the ECF (Guyton & Hall, 2006;Louden, 2009). …”

“…Further, water losses must be replaced with water intake within a very short period of time in order for the individual to maintain water balance and avoid the inevitable and rapid development of dehydration (Louden, 2009). …”

“…Additionally, older adults are more likely than younger adults to be put on diuretic medication due to increased incidence of hypertension (Rosenthal, Shamiss, & Holtzman, 2001). Diuretic medications are meant to decrease hypertension by increasing water losses in the urine (Abdallah et al, 2009;Berl, 2008;Louden, 2009). Therefore the eligibility criteria in this study excluded individuals on diuretic medications.…”