Fluids & Electrolytes Flashcards
Major cation intracellular and extracellular
outside: Na+
inside: K+
Main anions in body fluids
PO4, Cl, bicarb
What makes up total body water volume?
ICF
ECF: interstitial (80%) + plasma (20%)
Water makes up what percent of body?
60%
What is colloid typically composed of?
5% albumin in water
Replace blood with ________.
blood
Resuscitate with what fluid replacement?
isotonic fluid or colloid
Replace ECF depletion with ________.
isontonic (NS or LR)
Rehydrate with _________.
hypotonic (D5W)
Net effect of IV normal saline
increase water and volume in the vascular and intersititial spaces, but NOT the intracellular space
Net effect of IV whole blood
ONLY increase intravascular volume space; RBCs can’t across compartments
Net effect of IV colloid (5% albumin)
increase water and volume in the vascular and intersititial spaces, but NOT the intracellular space
- same as NS, but stays in intravascular space a little longer
Net effect of IV Dextrose 5%
small increase in ICF and ECF fluid
behaves like pure water flowing freely across all compartments
Examples of hyperosmotic fluids that pull water from interstitial AND intercellular spaces to balance osmolality
Mannitol, D50, 25% albumin
Do not use ______ for resuscitation.
hypotonic fluids
Which type of fluids pull fluids from ICF to ECF to balance tonicity?
hypertonic fluids (3% saline)
4cc, 2cc, 1cc rule for fluids
4 cc for the first 10 kg
2 cc for the next 10 kg
1 cc for each kg after
What is cc/hr rate of fluids for a 70 kg adult who is euvolemic?
4 cc for the first 10 kg = 40cc
2 cc for the next 10 kg = 20cc
1 cc for each kg after = 50cc
110 cc/hr
How to calculate daily maintenance fluid requirements?
0-10 kg: 100 ml/kg
10-20 kg: 1000 ml + 50 ml/kg for each kg over 10
20 kg: 1500 ml + 20 ml/kg for each kg over 20
What are daily maintenance requirements of sodium, chloride, and potassium?
Na+ 3 meq/kg
Cl- 5 meq/kg
K+ 2 meq/kg
A 70 kg male is 2 days post-colectomy. He is euvolemic, and he is NPO. His electrolytes are normal. His urine output is 63 ml/hour. He has a post-op drain with 100 ml serous output every 6-hours.
How much fluid does he need in the next 24 hours?
Insensible losses = 500 ml
63 ml/hr x 24 hours = 1500 ml
100 ml x 4 (four 6-hours in 24-hours) = 400 ml
His losses will be 2400 ml in 24 hours, so he needs 2400 ml, or 100 ml/hr
A 70 kg male is 2 days post-colectomy needs 2400 ml/day because his is NPO. His electrolytes are normal.
What do his losses look like?
Insensible - water
Urine – water and some electrolytes (~1/2NS)
Drain - serum
Which IV fluids have potassium?
LR and D51/2NS-20 K+
Which IV fluids have glucose?
D5W, D5NS, D51/2NS
cc in can of soda?
375 cc
Which fluid type and how much is bolus dosing amount?
use isotonic fluids
bolus is 10-20 ml/kg in hypovolemia
10 kg child = 100-200 ml, 100 kg adult = 1-2 L
Why do bolus dosing?
rapidly increase intravascular volume when there is evidence of dehydration and hypoperfusion
How to treat hypokalemia?
Non-life threatening (K less than 2.5) or asymptomatic: oral KCl 20-40 mmol q4-6 hrs x 4 doses, redraw next morning
Life-threatening: IV KCl 40 mmol over 2 hrs via central catheter, redraw every 30 min
How to treat hyperkalemia?
“C-Big-Kay-Di”
C – Calcium gluconate (stabilizes cardiac membrane)
B – Beta-2 agonists like nebulized albuterol or Bicarbonate (both shift K into cells)
IG – Insulin + Glucose (insulin shifts K into cells + glucose to avoid hypoglycemia)
K – Kayexalate (binds K in gut, excreted in feces lowering total body K stores)
DI – DIuretics (lasix) or DIalysis (if refractory to all other treatment options)
Etiology of hyponatremia with hypovolemia and low FE Na and sodium urine output?
vomiting, diarrhea, fluid loss (third spacing)
Etiology of hyponatremia with hypovolemia and high FE Na (> 1%) and sodium urine output?
Diuretics
Aldosterone deficiency
Renal tubular dysfunction
Etiology of hyponatremia with hypervolemia and low FE Na?
CHF
Cirrhosis
Renal failure
When to use hypertonic saline?
severe life-threatening symptoms of euvolemic hyponatremia - seizures, coma, impending respiratory distress
Etiology of euvolemic hyponatremia?
Polydipsia if low urine osmolality
SIADH if high urine osmolality
How to treat hyponatremia?
Hypovolemic - NS
Hypervolemic - treat underlying cause (eg. CHF)
Euvolemic - restrict water intake, NS or hypertonic saline
Why must sodium levels be corrected slowly?
avoid central pontine myelinolysis (cerebral edema)
Treatment of hypernatremia
NS if hemodynamically unstable
Hypotonic fluid if stable - drink water, IV fluids
Rate of correction for acute vs chronic hypernatremia
Acute 1 mmol/L/h
Chronic 0.5 mmol/L/h
How to manage hyperglycemic syndromes?
Fluids: crystalloids, add glucose when 250-300 mg/dL
Regular insulin
Electrolytes: K if less than 3.3 mmol/L
What glucose range is the goal for hyperglycemic patient who is critically illness?
140-180 mg/dL
Give _____ for hyperkalemia with ECG changes.
calcium
Limit increase in serum Na to _______ in first 24 hours in symptomatic hyponatremia.
8-12 mmol/L
Patients with hypernatremia and hemodynamic instability should have __________ administered.
normal saline
Potassium should be added to fluids in hyperglycemic syndromes as soon as K ________ and urine output is adequate.
K less than 5 mmol/L
Why should D5W (hypotonic) not be given to infants or patients with a head injury?
may cause cerebral edema
