Fluid Deficit Vs Excess

Fluid balance is a foundational nursing competency. Maintaining homeostasis requires precise management of fluid intake and output, electrolyte balance, and vascular volume. Fluid balance knowledge is used in virtually every clinical specialization — from cardiac and renal nursing to surgical care, obstetrics, and critical care. Body fluid compartments: - Total body water (TBW): roughly 50–60% of body weight in a typical adult (about 60% in non-elderly men and 50% in non-elderly women, and lower in older adults because lean mass falls with age); individual variation is substantial, and these proportions are approximations rather than measurements for one patient - Intracellular fluid (ICF): 2/3 of TBW — inside cells - Extracellular fluid (ECF): 1/3 of TBW — outside cells - Intravascular: plasma (within blood vessels), about one-quarter of the ECF - Interstitial: between cells and vessels (lymphatics), about three-quarters of the ECF - Transcellular: CSF, pleural, pericardial, peritoneal, synovial fluid Osmolality controls fluid movement: - Water moves from areas of low osmolality → high osmolality (osmosis) - Normal serum osmolality: approximately 275–295 mOsm/kg (the interval is laboratory-specific; use the range printed...