Fluid, Electrolyte, and AcidBase Balance
Reference
Taylor, C., Lillis, C., & LeMone, P.
(2005). Fundamentals of nursing (5th
ed.). Philadelphia, PA: Lippincott
Williams & Wilkins.
Chapter 46
Competencies for Ch 46:
Fluid, Electrolyte, & Acid-Base Balance
By the end of the unit, the student will:
1.
Describe the anatomy and physiology
related to body fluids, fluid & electrolyte,
and acid-base balance
2.
Describe age-related differences in body
fluid content and effect on fluid balance
status
3.
Describe how to promote and maintain fluid
& electrolyte, and acid-base balance
Competencies for Ch 46:
Fluid, Electrolyte, & Acid-Base Balance
(continued)
By the end of the unit, the student will:
4.
Describe specific variables that may
influence fluid & electrolyte, and acid-base
balance
5.
Teach clients about specific conditions that
can lead to fluid & electrolyte imbalance,
and acid-base imbalance
6.
Describe care for clients at risk for or with
actual problems related to fluid &
electrolyte, and acid-base balance
Functions of Water in the Body




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
Transporting nutrients to cells and wastes from cells
Transporting hormones, enzymes, blood platelets,
and red and white blood cells
Facilitating cellular metabolism and proper cellular
chemical functioning
Acting as a solvent for electrolytes and
nonelectrolytes
Helping maintain normal body temperature
Facilitating digestion and promoting elimination
Acting as a tissue lubricant
Two Compartments of Fluid in
the Body


Intracellular fluid (ICF) — fluid within
cells (70%)
Extracellular fluid (ECF) — fluid
outside cells (30%)

Includes intravascular and interstitial
fluids
Variations in Fluid Content


Healthy person — total body water is
50% to 60% of body weight
An infant has considerably more body
fluid and ECF than an adult


More prone to fluid volume deficits
Sex and amount of fat cells affect body
water

Women and obese people have less
body water
ELECTROLYTES

Terminology

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




Ions
Electrolytes
Cations
Anions
Non-electrolytes
Solvents
Solutes
Electrolytes

Ions



Cations — positive charge
Anions — negative charge
Homeostasis — total cations equal to
total anions
Fluid Balance


Solvents — liquids that hold a
substance in solution (water)
Solutes — substances dissolved in a
solution (electrolytes and nonelectrolytes)
MORE ELECTROLYTES
Measurement
Based on chemical activity
Regulation
Water distribution
Acid-base balance
Neuromuscular excitability
COMMON ELECTROLYTES
Sodium (Na++)
Functions

Regulates volume of body fluids

Maintains water balance

Regulates ECF

Influences ICF

Generation and transmission of nerve
impulses

Sodium-Potassium pump

POTASSIUM (K+)



Major cation in ICF
Reciprocal to sodium
Functions




Regulates cellular enzyme activity and water
content
Transmission of nerve and muscle impulses
Metabolism of proteins and carbohydrates
Regulation of acid-base balance by cellular
exchange with H+
CALCIUM (Ca++)


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

Most abundant electrolyte in body
99% found in bones and teeth
Functions
Nerve impulse transmission and blood
clotting
Catalyst for muscle contraction
Thickness and strength of of cell
membranes
MAGNESIUM (Mg++)


Second most important cation in ICF
Functions





Metabolism of carbohydrates and proteins
Vital enzyme actions
Protein and DNA synthesis
Maintaining intracellular levels of Potassium
Maintain electrical activity in nervous tissue and
muscle tissue membranes
CHLORIDE (Cl-)


Chief extracellular anion
Functions




Works with sodium to maintain osmotic
pressure of blood
Regulates acid-base balance
Buffering action during O2/CO2 exchange
Production of Hydrochloric acid in
digestion
BICARBONATE (HCO3-)



Major chemical base buffer
Found in ECF and ICF
Function

Essential for acid base balance. Works
with carbonic acid to make up the body’s
acid base buffer system
PHOSPHATE (PO4-)



Major anion in body cells
Buffer in ICF and ECF
Functions



Maintains body’s acid-base balance
Cell division and transmission of heredity
Chemical reactions use of Vit B, CHO
metabolism, nerve and muscle action
OTHER ELECTROLYTES

Sulfate




Anion
ICF
Excreted in the kidney
Lactic acid


Anion
Facilitates diffusion to and from
capillaries
FLUID AND ELECTROLYTE
MOVEMENT

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Osmosis – Fluid passes from areas of low
solute concentration to areas of high solute
concentration
Diffusion – tendency of solutes to move freely
from areas of high concentration to low
concentration (down hill)
Active Transport – requires energy to move
through a cell membrane from area of lesser
concentration to one of greater concentration
Filtration – passage of fluid through a
permeable membrane. Movement is from high
to low pressure
Osmolarity of a solution



Isotonic — same concentration of
particles as plasma
Hypertonic — greater concentration of
particles than plasma
Hypotonic — lesser concentration of
particles than plasma
Filtration


Colloid osmotic pressure
Hydrostatic pressure
Source of Fluids for the Body



Ingested liquids
Food
Metabolism
Fluid Losses


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
Kidneys — urine
Intestinal tract — feces
Skin — perspiration
Insensible water loss
Fluid Imbalances




Involves either volume or distribution of
water or electrolytes
Hypovolemia — deficiency in amount of
water and electrolytes in ECF with near
normal water/electrolyte proportions
Dehydration — decreased volume of
water and electrolyte change
Third-space fluid shift — distributional
shift of body fluids into potential body
spaces
Fluid Volume Excess



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Hypervolemia — excessive retention
of water and sodium in ECF
Overhydration — above normal
amounts of water in extracellular
spaces
Edema — excessive ECF accumulates
in tissue spaces
Interstitial-to-plasma shift —
movement of fluid from space
surrounding cells to blood
Electrolyte Imbalances

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Hyponatremia and hypernatremia
Hypokalemia and hyperkalemia
Hypocalcemia and hypercalcemia
Hypomagnesemia and
hypermagnesemia
Hypophosphatemia and
hyperphosphatemia
Nursing Assessments



Identify patients at risk for imbalances.
Determine a specific imbalance is
present and its severity, etiology, and
characteristics.
Determine effectiveness of plan of
care.
Parameters of Assessment

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Nursing history and physical
assessment
Fluid intake and output
Daily weights
Laboratory studies
Lab Studies to Assess for
Imbalances

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Complete blood count
Serum electrolytes
Urine pH and specific gravity
Arterial blood gases
Risk Factors for Imbalances

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Pathophysiology underlying acute and
chronic illnesses
Abnormal losses of body fluids
Burns
Trauma
Therapies that disrupt fluid and
electrolyte balance
Nursing Diagnoses Related to
Imbalances

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
Excess fluid volume
Deficient fluid volume
Risk for imbalanced fluid volume
Expected Outcomes

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
Maintain approximate fluid intake and
output balance (2500mL intake and
output over 3 days)
Maintain urine specific gravity within
normal range (1.010 to 1.025)
Practice self-care behaviors to
promote balance
Implementing

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Dietary modifications
Modifications of fluid intake
Medication administration
IV therapy
Blood and blood products replacement
TPN
Administering Medications

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Mineral-electrolyte preparations
Diuretics
Intravenous therapy
Intravenous Therapy

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Vascular access devices
Peripheral venous catheters
Midline peripheral catheter
Central venous access devices
Implanted ports
Vein Site Selection

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Accessibility of a vein
Condition of vein
Type of fluid to be infused
Anticipated duration of infusion
Administering Blood and Blood
Products
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Typing and cross-matching
A, B, AB, and O type blood
Rh Factor
Selecting blood donors
Initiating transfusion
Transfusion reactions
HOMEOSTASIS
PROCESS OF MAINTAINING
A STABLE STATE UNDER
VARIABLE CONDITIONS
MECHANISMS OF
HOMEOSTASIS

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Kidneys
Cardiovascular system
Lungs
Adrenal Glands
Thyroid Gland
Parathyroid Gland
Gastrointestinal tract
Nervous system
Primary Organs of
Homeostasis



Kidneys normally filter 170 L plasma,
excrete 1.5 L urine.
Cardiovascular system pumps and
carries nutrients and water in body.
Lungs regulate oxygen and carbon
dioxide levels of blood.
Primary Organs of
Homeostasis, continued


Adrenal glands help body conserve
sodium, save chloride and water, and
excrete potassium.
Thyroid gland increases blood flow in
body and increases renal circulation.
ACID – BASE BALANCE

Acid contains hydrogen atoms that can be
released


Base accepts hydrogen atoms



Acidosis too many circulating H+ ions
Alkalosis not enough H+ ions in the ECF
pH is the unit of measure used to describe
acid base balance
Buffer prevents ECF from becoming too
acidic or too alkaline
BUFFER SYSTEMS



Carbonic Acid-Sodium Bicarbonate
System
Phosphate Buffer System
Protein Buffer System
IMBALANCE IN ACID –
BASE BALANCE

Respiratory Alkalosis


Respiratory Acidosis


Excess in carbonic acid in the ECF
Metabolic Alkalosis


Deficit in carbonic acid in the ECF
Excess of bicarbonate in the ECF
Metabolic Acidosis

Deficit of bicarbonate in the ECF
EXERCISE #1

For the patient with hyperkalemia related to
decreased renal excretion secondary to
potassium conserving diuretic therapy” an
appropriate expected outcome would be
which of the following?
a)
b)
c)
d)
Bowel motility will be restored within 24 hours
after beginning supplemental K+
ECG will show no cardiac arrhythmias within 48
hours after removing salt substitutes, coffee, tea
and other K+ rich foods from the diet
ECG will show no cardiac arrhythmias within 24
hours after beginning supplemental K+
Bowel motility will be restored within 24 hours
after eliminating salt substitutes, coffee, tea, and
other K+ rich foods from the diet
EXERCISE #2

Which of the following nursing diagnoses
would you expect to find based on the
effects of fluid and electrolyte imbalance on
human functioning?
a)
Constipation related to immobility
Pain related to surgical incision
Altered thought processes related to cerebral
edema, including mental confusion and
disorientation
Health risk for infection related to inadequate
personal hygiene
b)
c)
d)
EXERCISE #3

a)
b)
c)
d)
A nurse who diagnoses a patient as having
“fluid volume excess” related to
compromised regulatory mechanisms
(kidneys) may have been alerted by which
of the following symptoms?
Muscular twitching
Distended neck veins
Fingerprinting over sternum
Nausea and vomiting
EXERCISE #4

a)
b)
c)
d)
Pumping uphill would describe which of
the following means or transporting
materials to and from intercellular
compartments?
Osmosis
Diffusion
Filtration
Active transport