Chapter 29
Fluids and Electrolytes
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Fluid Balance

Total body water


Composed of:
• Intracellular fluid (ICF)
• Interstitial fluid (ISF)
• Plasma volume (PV)
60% of adult human body is water
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Fluid Balance (cont’d)

Intravascular fluid (IVF)


Fluid inside blood vessels
Extravascular fluid (EVF)

Fluid outside blood vessels
• Lymph, cerebrospinal fluid
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Fluid Balance (cont’d)

Extravascular volume



Plasma
Interstitial fluid (ISF): fluid in space between cells,
tissues, and organs
Extracellular volume


ISF (interstitial fluid)
ICF (intracellular fluid)
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Distribution of Total Body Water
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Fluid Balance (cont’d)

Plasma proteins exert constant osmotic pressure



Colloid oncotic pressure (COP)
Normally 24 mm Hg
ISF exerts hydrostatic pressure (HP)

Normally 17 mm Hg
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Colloid Osmotic Pressure
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Fluid Balance (cont’d)



Edema
Dehydration and fluid loss
Acid-base balance
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Crystalloids



Solutions containing fluids and electrolytes that
are normally found in the body
Do not contain proteins (colloids)
No risk for viral transmission, anaphylaxis, or
alteration in coagulation profile
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Crystalloids (cont’d)


Better for treating dehydration rather than
expanding plasma volume
Used as maintenance fluids to:

Compensate for insensible fluid losses
 Replace fluids
 Manage specific fluid and electrolyte disturbances
 Promote urinary flow
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Crystalloids (cont’d)





Normal saline (0.9% sodium chloride)
Half normal saline (0.45% sodium chloride)
Hypertonic saline (3% sodium chloride)
Lactated Ringer’s
D5W
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Crystalloids (cont’d)

Indications include:

Acute liver failure
 Acute nephrosis
 Adult respiratory distress syndrome
 Burns
 Cardiopulmonary bypass
 Hypoproteinemia
 Renal dialysis
 Reduction of the risk for DVT
 Shock
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Crystalloids (cont’d)

Adverse effects

May cause edema, especially peripheral or
pulmonary
 May dilute plasma proteins, reducing COP
 Effects may be short-lived
 Prolonged infusions may worsen alkalosis or acidosis
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Colloids



Protein substances
Increase COP
Move fluid from interstitial compartment to
plasma compartment (when plasma protein
levels are low)



Albumin 5% and 25% (from human donors)
Dextran 40, 70, or 75 (a glucose solution)
Hetastarch (synthetic, derived from cornstarch)
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Colloids (cont’d)

Adverse effects

Usually safe
 May cause altered coagulation, resulting in bleeding
 Have no clotting factors or oxygen-carrying capacity
 Rarely, dextran therapy causes anaphylaxis or renal
failure
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Blood Products




Only class of fluids that are able to carry oxygen
Increase tissue oxygenation
Increase plasma volume
Most expensive and least available fluid
because they require human donors
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Blood Products (cont’d)

Increase COP and PV

Pull fluid from extravascular space into intravascular
space (plasma expanders)
 RBC products also carry oxygen
 Increase body’s supply of various products (such as
clotting factors, hemoglobin)
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Blood Products (cont’d)

Indications

Cryoprecipitate and plasma protein factors (PPF)
• Management of acute bleeding (greater than 50% slow blood
loss or 20% acutely)

Fresh frozen plasma (FFP)
• Increase clotting factor levels in patients with demonstrated
deficiency
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Blood Products

Indications (cont’d)

Packed red blood cells (PRBCs)
• To increase oxygen-carrying capacity in patients with anemia,
in patients with substantial hemoglobin deficits, and in
patients who have lost up to 25% of their total blood volume

Whole blood
• Same as for PRBCs, except that whole blood is more
beneficial in cases of extreme (greater than 25%) loss of
blood volume because whole blood also contains plasma
• Contains plasma proteins, which help draw fluid back into
blood vessels from surrounding tissues
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Classroom Response Question
A patient is taken to the trauma unit after a
motorcycle accident. It is estimated that he has
lost 30% of his blood volume and he is in
hypovolemic shock. The nurse anticipates a
transfusion with which blood product?
A. Packed red blood cells
B. Whole blood
C. Cryoprecipitate
D. Fresh frozen plasma
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Blood Products (cont’d)

Adverse effects
Incompatibility with recipient’s immune system
 Crossmatch testing
 Transfusion reaction
 Anaphylaxis
 Transmission of pathogens to recipient (hepatitis,
HIV)

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Electrolytes

Principal ECF electrolytes



Principal ICF electrolyte


Sodium cations (Na+)
Chloride anions (Cl−)
Potassium (K+)
Others

Calcium, magnesium, phosphorus
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Potassium




Most abundant positively charged electrolyte
inside cells
95% of body’s potassium is intracellular
Potassium content outside of cells ranges from
3.5 to 5 mEq/L
Potassium levels are critical to normal body
function
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Potassium (cont’d)

Potassium obtained from foods


Fruit and fruit juices (bananas, oranges, apricots,
dates, raisins, broccoli, green beans, potatoes,
tomatoes), meats, fish, wheat bread, and legumes
Excess dietary potassium excreted via kidneys

Impaired kidney function leads to higher serum levels,
possibly toxicity
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Potassium (cont’d)
Hyperkalemia: excessive serum potassium;
serum potassium level over 5.5 mEq/L





Potassium supplements
ACE inhibitors
Renal failure
Excessive loss from cells
Potassium-sparing diuretics




Burns
Trauma
Metabolic acidosis
Infections
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Potassium (cont’d)


Hypokalemia: deficiency of potassium; serum
potassium level less than 3.5 mEq/L
Excessive potassium loss (rather than poor dietary
intake)







Alkalosis
Corticosteroids
Diarrhea
Ketoacidosis
Laxative misuse
Hyperaldosteronism
Increased secretion
of mineralocorticoids
 Burns
 Thiazide, thiazide-like,
and loop diuretics
 Vomiting
 Malabsorption
 Others
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Potassium (cont’d)

Hypokalemia, in the presence of digoxin therapy,
can cause digoxin toxicity, resulting in serious
ventricular dysrhythmias
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Potassium (cont’d)

Potassium is responsible for:

Muscle contraction
 Transmission of nerve impulses
 Regulation of heartbeat
 Maintenance of acid-base balance
 Isotonicity
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Classroom Response Question
Which condition does the nurse identify as a late
manifestation of hypokalemia?
A. Muscle weakness
B. Hypotension
C. Palpitations
D. Lethargy
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Potassium (cont’d)

Main indication


Treatment or prevention of potassium depletion when
dietary means are inadequate
Other therapeutic uses


Stop irregular heartbeats
Management of tachydysrhythmias that can occur
after cardiac surgery
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Potassium (cont’d)

Adverse effects



Oral preparations
• Diarrhea, nausea, vomiting, GI bleeding, ulceration
IV administration
• Pain at injection site
• Phlebitis
Excessive administration
• Hyperkalemia
• Toxic effects
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Potassium (cont’d)

Hyperkalemia manifestations


Muscle weakness, paresthesia, paralysis, cardiac
rhythm irregularities (leading to possible ventricular
fibrillation and cardiac arrest)
Treatment of severe hyperkalemia


IV sodium bicarbonate, calcium gluconate or calcium
chloride, dextrose with insulin
Sodium polystyrene sulfonate (Kayexalate) or
hemodialysis to remove excess potassium
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Classroom Response Question
A patient is hypokalemic and will be receiving
intravenous potassium. The patient is not on a
heart monitor. How should the nurse administer
the potassium replacement?
A. IV push
B. No more than 10 mEq/hr
C. No more than 20 mEq/hr
D. 40 mEq/hr
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Sodium



Most abundant positively charged electrolyte
outside cells
Normal concentration outside cells is 135 to 145
mEq/L
Maintained through dietary intake of sodium
chloride

Salt, fish, meats, foods flavored or preserved with salt
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Sodium (cont’d)

Hyponatremia: sodium loss or deficiency; serum
levels below 135 mEq/L

Symptoms
• Lethargy, stomach cramps, hypotension, vomiting, diarrhea,
seizures

Causes
• Same causes as hypokalemia; also excessive perspiration
(during hot weather or physical work), prolonged diarrhea or
vomiting, or renal disorders
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Sodium (cont’d)

Hypernatremia: sodium excess; serum levels
over 145 mEq/L

Symptoms
• Water retention (edema), hypertension
• Red, flushed skin; dry, sticky mucous membranes; increased
thirst; elevated temperature; decreased urine output

Causes
• Poor renal excretion stemming from kidney malfunction;
inadequate water consumption and dehydration
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Sodium (cont’d)

Sodium is responsible for:

Control of water distribution
 Fluid and electrolyte balance
 Osmotic pressure of body fluids
 Participation in acid-base balance
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Sodium (cont’d)

Main indication



Treatment or prevention of sodium depletion when
dietary measures are inadequate
Mild
• Treated with oral sodium chloride and/or fluid restriction
Severe
• Treated with intravenous normal saline or lactated Ringer’s
solution
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Sodium (cont’d)

Adverse effects


Oral administration
• Nausea, vomiting, cramps
IV administration
• Venous phlebitis
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Nursing Implications







Assess baseline fluid volume and electrolyte
status
Assess baseline vital signs
Assess skin, mucous membranes, daily weights,
I&O
Before giving potassium, assess ECG
Assess for contraindications to therapy
Assess transfusion history
Establish venous access as needed
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Nursing Implications (cont’d)



Monitor serum electrolyte levels during therapy
Monitor infusion rate, appearance of fluid or
solution, infusion site
Observe for infiltration, other complications of IV
therapy
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Nursing Implications (cont’d)

Parenteral infusions of potassium must be
monitored closely


IV potassium must not be given at a rate faster than
10 mEq/hr to patients who are not on cardiac
monitors. For critically ill patients on cardiac monitors,
rates of 20 mEq/hr or more may be used.
NEVER give as an IV bolus or undiluted
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Nursing Implications (cont’d)

Oral forms of potassium


Must be diluted in water or fruit juice to minimize GI
distress or irritation
Monitor for complaints of nausea, vomiting, GI pain,
or GI bleeding
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Classroom Response Question
A patient with a serum potassium of 6.0 mEq/L is
ordered polystyrene sulfonate (Kayexalate) via the
NG. When administering the medication the nurse
should
A. administer the drug with sorbitol.
B. administer the drug with water.
C. administer the drug with an antacid.
D. administer the drug with a laxative.
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Nursing Implications (cont’d)




Administer colloids slowly
Monitor for fluid overload and possible heart
failure
For blood products, follow administration
procedures closely
Monitor closely for signs of transfusion reactions
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Classroom Response Question
Which solution should the nurse administer with
packed red blood cells?
A. Lactated Ringer’s
B. 0.9% sodium chloride
C. D5W
D. 0.45% sodium chloride
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Nursing Implications (cont’d)

Monitor for therapeutic response

Normal lab values
• RBCs, WBC, H&H, electrolyte levels
 Improved fluid volume status
 Increased tolerance to activities

Monitor for adverse effects
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