Lecture 5: IV Fluids

Lecture 5: IV Fluids Body Fluid · 60% of body fluid/weight is water · Intracellular Fluid (ICF) = 40% · Extracellular Fluid (ECF) = 20% ↳ interstitial: 16% ↳ plasma: 4% · water travels freely through the compartments by osmosis, but larger particles require active transport · recommended fluid intake/day = 2.5L fluid (including food) · Major electrolytes: Sodium, potassium, magnesium, phosphate, chloride, calcium Osmolality · dependent on number of dissolved solutes in a fluid: sodium, glucose, urea · expected osmolality of blood: 275-295 mOsm/kgH20 · changes in osmolality causes fluid shifts via osmosis ↳ dehydration = increases osmolality ↳ overhydration = decreases osmolality - Tonicity · a relative measurement of IV fluid's osmolality · tonicity dictates the movement of fluids between compartments · main solutes: sodium & dextrose · categories: ① Isotonic = same as plasma ② Hypertonic = higher than plasma ③ Hypotonic = lower than plasma Homeostasis IV Fluids ① Colloids (protein based) Primarily used to expand blood volume · aka: plasma expanders · supply large proteins into ECF · stays in circulation + draws fluids towards it · tx for hypovolemic shock (low volume shock) ↳ contra. in most other cases b/c fluid overload ↳ renal workload, high cause of allergy · eg. Plasbumin, Aburet ② Crystalloids (water based) · supplies H20, electrolytes, and other solutes (eg. glucose) · can more between ECF & ICF ↳ tonicity directs fluid movement ↳ especially sodium & dextrose amounts Less effective in expanding blood volume In the 'Bag' VS. in the 'Body' · high protein content = although isotonic in the "bag” they are suddenly “hypertonic” in the body eg. Albumin 5% (isotonic colloid behaves hypertonic due to protein) · high dextrose = in the body dextrose is quickly utilized and the remaining fluid becomes isotonic or hypotonic eg. D5 NS (mildly hypertonic in bag, becomes isotonic in body) Fluid Terminology · fluid maintenance: meeting body requirements (PO, IV, SC) · fluid resuscitation: replacing deficits ↳ oral if minor, IV if concerning (goal is adequate perfusion) · fluid restriction (may be due to high BP) · NPO: nothing by mouth, fluids given by IV Fluid Maintenance · 35ml/kg/day of water · potassium, sodium, and chloride · 50-100g/day of glucose to limit 'starvation' Ketosis · "4/2/1" Rule (pediatrics) ↳ 4 ml/kg/hr for 1st 10kg ↳ 2 ml/kg/hr for 2nd 10 kg ↳ 1 ml/kg/hr for remaining kgs for emergency volume replacement w/o Isotonic Fluids Good fluid shifting into diff compartments · Lactated Ringers (LR) ↳ Na (130 mEq), Potassium (4 mEq), Calcium (2.7 mEq), Chloride (109 mEq), Lactate (28 mEq) ↳ S/e: hyperkalemia, no dextrose ↳ contra for kids b/c of high electrolytes · NS (0.9% ) ↳ 154 mEq Na + 154 mEq Cl ↳ #1 resuscitation fluid for adults ↳ long-term s/e: hypokalemia, no dextrose! · 5% albumin (Colloid) isotonic, but hypertonic in the body · Dextran 40 (Colloid) Hypertonic Fluids Fluid out of cells · high glucose, high sodium, or both (or colloid) · D5NS Hypertonic, but isotonic in the · D5LR body when dextrose is used up · D10W · D5 0.45% NaCI (D5 1/2 NS) ↳ hypertonic in bag, becomes isotonic in body Hypotonic Fluids Fluid into cells ↳ Na (77mEq), Cl (77 mEq), Dextrose (50 mEq) · Low NaCl, low dextrose: ↳ s/e: hyponatremia ↳ 0.45% NaCl (1/2 NS) ↳ pediatrics #1 choice for maintenance, check K + ↳ 3.3% dextrose, 0.3% sodium (2/3 1/3) · 3%. NaCI (3% NS) → treats hyponatremia · Isotonic/hypotonic fluids · 25% Albumin (colloid) ↳ D5 0.2% NaCl ↳ 25% albumin, up to 160 mEq Na ↳ D5W ↳ caution! · IV volume expander · 25% albumin IV = 3.5 times volume of additional fluid into circulation in 15 mins Blood Loss TX · RBC · Whole blood ↳ not 1st choice, allergenic · Platelets · FFP (fresh frozen plasma) ↳ provides clotting factors Sodium Issues: 135-145 · Hyponatremia < 135 mEq/L ↳ cause: loss of sodium via GI or GU, or sweating ↳ eg. diuretic drugs, dehydration - hyponatremic ↳ Tx: D5NS · Hypernatremia > 145 mEq/L ↳ cause: renal failure, high Na intake, diarrhea ↳ Tx: restrict salt intake, diuretics to remove Na, IV fluids Potassium Issues 3.5-5 · Hypokalemia K < 3.5 mEq/L ↳ cause: drugs (potassium wasting diuretics, eg. furosemide), N&V ↳ Tx: KCL (IV or PO) · Hyperkalemia K > 5 mEq/L ↳ cause: drugs (potassium sparing diuretics), renal disease ↳ Tx: Kayexalate (PO, NG) · binds K + in intestines to excrete via stool Extra IV Notes: · Fluid losses occur constantly by excretion, primarily in stool or urine ↳ 1000mL urine, up to 200mL stool, 400 mL respiration · basic fluid requirement is 35mL/kg/day ↳ "4/2/1"rule for pediatrics · general rule: fluids high in sodium or glucose are hypertonic · patients should not remain NPO for extended periods of time *** · hypotonic fluids: diabetic Ketoacidosis, hypernatremia, dehydration · hypertonic fluids: cerebral edema, severe hyponatremia, hypervolemic shock · resuscitation fluids: 1st choice NS or LR, 2nd choice Colloids · maintenance fluid in pediatrics ideally requires electrolytes and dextrose ↳ D5. 45% NS with KCI (20 mEq/L) ** A More IV Notes: * AD • fluid losses occur constantly by excretion primarily in stool and urine - 1000-1200 mL in urine - 100-200 mL in stool - 400 mL respiration • Adult maintenance fluids should be LR, NS, or D5NS • Children maintenance fluids is D5 1/2 NS • In dehydration and vomiting or diarrhea patients you want to administer isotonic fluids like LR or NS