Water Humans can live 1 month without food and only 6 days without water Muscle 60%, Fat 30%, Bone 10% water, with total weight 50-60%, infants 80% Regulation of fluid balance, aquaproteins. Albumin, Na, K, kidneys, cardia function Intracellular 65% of fluid, Extracellular 35% with Extracellular more easily lost

Extracellular Interstitial, fluid located between or around cells and used for transport Intravascular, fluid in blood vessels know as plasma, or without clotting factors serum Lymphatic, collects fluid outside the venous system and returns it to the heart Transcellular fluid, found in pericardium, pleural space, gastrointestinal

Absorption Total volume, 15L/d intestine, 5L/d in colon, or held in interstitial space as edema With trauma capillaries become permeable and lack of proteins off set osmotic pressure causing swelling Caused by DVT, heart failure, severe protein loss, and deadly in pulmonary and cerebral excess 80% of fluid comes from liquids, 20% from foods, with needs based on wt in Kg - 20kg + 1500ml, or KCALS/mL

Electrolytes Ions are charged elements, Na+ (cation), Cl- (anion) which form ionic bonds to form isotonic solutions With excess Na+, Cl- will shift fluid compartments to form balance, Na+ Extracellular, K+ Intracellular, HCO3- Intracelluar Minerals and proteins affect fluid balance by osmotic pressure, where solvents (H2O) crosses membranes and solutes don't Osmosis is the movement of solvents (H2O) across a semipermeable membrane by active or passive transport Active transport requires energy for Na/K pumps, while passive transport only needs hyper/hypo tonic elements

Osmolarity Passive movement of a solvent across a semipermeable membrane into a concentration of less particles Osmotic pressure is two concentrations both acting against each other on either side of a semipermeable membrane Osmolarity is the number of particles per volume of water, with serum blood at 275-295 mOsm/L Isotonic fluids are = blood osmolarity (D5W, 0.9% NaCl), less is hypotonic, more is hypertonic Water is hypotonic, milk is typically isotonic, and sodas are hypertonic

Regulation of Fluid Thirst occurs when 10% of the intravascular space is lost and when serum osmolarity rises Antidiuretic Hormone or Vassopressin, causes retention of fluid decreasing osmolarity and also increases PBH In diabetes insipidus (DI), ADH does not secrete and excess amount of fluid is lost Aldosterone retains sodium, which pulls fluid back into the body from the kidneys caused by hypotension

Water Balance Skim milk is 91%, EN formula is 70-80% hard water has Ca, Mg, and Fe+, soft water replaces these with Na 4 cups with food/d, mostly vegetables and metabolism produces 1 cup/d, except alcohol which requires H2O Sensible fluid loss is urine, emesis, and GI loss from stool that should count in total I/Os In extreme perspiration is >2L or 6-8% of UBW, with a L providing 40mEq Na, 3.9mEq K and 3.3 mEq Mg Hypoalbuminemia can cause < colloidal mOsm/L, resulting in third spacing or volume loss from the interstitial space

Water Balance At a minimum urine output must be >600ml/d to remove waste, typical output is 40-80ml/hr Gastric fluid loss is vomiting or NGT suction, decompression above the pylorus, pH< 6.8 Intestinal loss is diarrhea with 2-3L/d along with1L of bile Insensible loss is 1L from lungs, skin, and shivering which can be increased by illness, burns, fever

Water Balance 1L of fluid = 1kg, with mild loss 2-5%, moderate 5-10%, and severe >10%, causing hypotension I/Os should be equal, subtract diaper from fluid, or use a urinal for output Needs are wt/kg-20 +1500, in CHF 1400-1900ml, in ESRD 1000 + urine, mL/KCALS in obese

Water Balance OHT, should be hypotonic 200-310 mOsm/L, 2-3gm CHO, 45-90mEq Na, 20-25mEq K Hypertonic fluids should NOT be used, Gatorade, Juice >330 mOsm/L stays in the stomach, draws fluid out of the colon, cause diarrhea, reduces thirst For fluid overload 1000ml restriction, 2gm Na, and diuretics are typically used