Alyssa, Amanda, Heather, Lynn,
Sarah, Tamara, & Tracy
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60% of a person’s weight consists of fluid (water and
electrolytes)
Located in two compartments:
o Intracellular space
o Extracellular space
Intracellular space:
o Intracellular fluid (ICF) – fluid in the cells
• Extracellular space:
o Extracellular fluid (ECF) – fluid outside the cells
o Intravascular, interstitial and

transcellular
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Electrolytes in body fluids are active cells that
consist of positively charged chemicals, cations,
and negatively charged chemicals, anions.
Major cations in the body are Na, K, Ca, Mg,
and H.
Major anions in the body are Cl, HCO3, PO3-4,
SO2-4, and Proteinate.
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Each major cation and anion are present in
varying degrees in the extracellular fluid of the
cells.
In the intracellular fluid, K, Mg, and Na are the
only cations present, and all of the major
anions are accounted for.
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Electrolyte concentration in the body :
mmol/L (millimole per litre) – 1/1000 of a
mole dissolved in one litre of solution
mEq/L (milliequivalent per litre) - one
thousandth of 1 equivalent of a specific
substance dissolved in 1 L of solution or
plasma.
mOsm/L (milliosmoles per litre) – 1/1000
milliosmoles dissolved in one litre of solution
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Intracellular fluid
o
o
o
o
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Potassium – 150 mmol/L
Magnesium – 40 mmol/L
Sodium – 10 mmol/L
Phosphates – 150 mmol/L
Extracellular fluids
o
o
o
o
o
o
Sodium – 142 mmol/L
Potassium – 5 mmol/L
Calcium – 5 mmol/L
Magnesium – 2 mmol/L
Chloride – 103 mmol/L
Bicarbonate – 26 mmol/L
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Electrolyte solution
Moves freely between the intravascular
compartment and interstitial spaces
Sterile water with added electrolytes
Approximate the mineral content of human
plasma
Isotonic, hypertonic and hypotonic
Long shelf life
Ex: 0.9%NaCl (Normal Saline) & Lactated
Ringer’s
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Plasma proteins
Molecules are too large to pass through the
capillary membranes
Expand intravascular volume, by pulling fluid
into the intravascular space
Sterile water and electrolytes but a component
of a colloidal substance
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Does not freely pass the semipermeable
membrane
Ex: dextran & Albumin
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Colloids have a longer duration of action
 Molecules remain within the intravascular compartment
longer
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Colloids are more expensive
 Some organizations have restrictions on the use of colloids
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There is no difference in life or death
Crystalloids reduce serum protein
concentrations and packed red cell volume
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increased risk of tissue edema.
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Solutions that have between 250 – 350
mOsm/L
Total osmolality close to ECF – therefore cells
do not shrink or swell
Expand the ECF volume – 1L fluid expands
ECF by 1 L
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Only expands plasma by 0.25 L
Need 3 L of isotonic fluid to replace 1 L of
blood
Because fluid diffuses quickly into ECF
compartment (w/in approx. 1 hr of admin)
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Na+ 154 mEq/L + Cl- 154 mEq/L (308
mOsm/L)
Expands ECF……so?
Used for: hypovolemic states, resuscitative
efforts, shock, diabetic ketoacidosis, metabolic
alkalosis, hypercalcemia, mild Na + deficit
Supplies excess of Na+ and Cl-
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Only solution to be administered with blood
products
Can be mixed with 5% dextrose – BUT this is a
hypertonic solution
Can cause FVE and hyperchloremic acidosis in
excessive volumes ----more susceptible
patients: those with compromised renal fxn,
heart failure, or edema
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Composition is similar to plasma (274
mOsm/L)
Lacks Mg++ …….Provides 170 calories/L
Used for: tx of hypovolemia, burns, fluid lost as
bile or diarrhea
Lactate metabolized rapidly into HCO3Should not be used in lactic acidosis (inability
to convert lactate to bicarb)or renal failure (K+
will cause hyperkalemia)
Not to be given with a pH > 7.5 d/t HCO3- --would result in alkalosis
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No electrolytes - (252 mOsm/L)
Provides 170 calories/L and free water – aid in
renal excretion in solutes
Used for: tx of hypernatremia, fluid loss,
dehydration
Contraindicated in: excessive amts in early postop
period, tx of FVD (dilutes electrolytes), head
injury, fluid resuscitation (can cause
hyperglycemia),
Use with caution in pts with renal or cardiac
disease b/c of risk of fluid overload
Converts to hypotonic solution as dextrose is
metabolized. Over time can cause water
intoxication d/t intracellular FVE
Less than 250 mOsm/L
 Less osmotic pressure than ECF
– gives to cells
 Purpose: replace cellular fluid, provide free
water for excretion of body wastes
 Used to: treat hypernatremia and other
hyperosmolar conditions
 Excessive infusions of hypo solutions leads to:
intravascular fluid depletion, decreased BP,
cellular edema, cell damage
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Na+ 77 mEq/L + Cl- 77 mEq/L (154 mOsm/L)
Provides Na+,Cl- and free water
Free water aids kidneys in elimination of solute
Lacking in electrolytes other than Na+ & ClUsed to: tx hypertonic dehydration, Na+ & Cldepletion and gastric fluid loss
Not indicated for third-space fluid shifts (burns,
traumatic injuries, malnutrition, liver disease) and
increased ICP
Administer cautiously – causes fluid shifts into
cells – can result in CV collapse and increased ICP
Greater than 350 mOsm/L
 Greater osmotic pressure than ECF
– takes from cells
 Draws water from ICF to ECF and causes cells
to shrink
 Rapid admin or large volumes: may cause
extracellular FVE = circulatory overload and
dehydration
 Cautious administration – ONLY when serum
osmolality has decreased to dangerously low
levels
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Na+ 513 mEq/L + Cl- 513 mEq/L (1026
mEq/L)
Highly hypertonic solution
Used to: tx hyponatremia
**Admin slowly and cautiously – can cause
intravascular volume overload & pulm edema
Assists in removing ICF excess
No calories supplied
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Hypertonic – 559 mOsm/L
Used to: tx fluid volume deficit, for daily
maintenance of body fluids & nutrition
Temporary effect on ICF – takes from cells until
dextrose metabolized
Supplies 170 calories/L
Becomes isotonic once dextrose metabolized
Acts the same as NS but provides calories
What is the difference between a
Cation and an Anion?
A Cation is positively charged
An Anion is negatively charged
Is there more sodium in Intracellular
or Extracellular fluid?
Extracellular
142 mmol/L in the Extracellular
10mmol/l in the Intracellular
What is an example of a cystalloid?
0.9%NaCl (Normal Saline)
Lactated Ringer’s
What is an example of a colloid?
Dextran
Albumi
What is the range of osmolality of
each type of solution?
>350
Hypertonic: _______
mOsm/L
250 – 350 mOsm/L
Isotonic: _______
< 250 mOsm/L
Hypotonic: ______
What kind of solution would be used
to increase the ICF?
Hypotonic
What kind of solution would be used
to decrease the ICF?
Hypertonic
What pH level is a contraindication to
infusion of Lactated Ringer’s? Why?
pH > 7.5
Rationale: because lactate is converted
to bicarb and this would cause alkalosis
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David, K. (2007). IV fluids: Do you know what’s
hanging and why?. Modern Medicine.
Day , R. A., Paul, P., Williams, B., Smeltzer , S. C., &
Bare, B. (2007). Textbook of medical-surgical nursing:
Concepts and challenges in patient management.
Philadelphia : Lippincott-Raven .
Smeltzer, S.C, & Baie. (2004). Fluid and electrolytes:
Balance and Distribution. IN Q. McDonald & D.
McMahan (Eds.), Brunner & Suddarth’s Thextbook of
Medical-Surgical Nursing (10th ed., pp. 249-294).
Philadelphia. PA: Lippincott Williams & Wilkins.
http://www.merricks.com/electrotech.html
http://www.bem.fi/book/03/03.htm