Chapter 7
Nursing Care of Clients with
Alterations in Fluid, Electrolyte, or
Acid-base Balance
Fluid Balance in the Body

Functions of fluid in the body
– medium for transport and exchange of
nutrients
– medium for metabolic reactions
– regulates body temperature
– form for body/cell structure and shock
absorber
– provides insulation and lubrication
Fluid Compartments
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Intracellular - fluid within the cells
extracellular - fluid outside of the cells
– interstitial - in the spaces between the cells
– intravascular - within the ateries and veins
– transcellular - urine, digestive secretions
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Third-spacing - trapped extracellular
fluid
Edema - accumulation in interstitial
spaces
ICF and ECF
ICF- fluid within the cells accounts for about 40% of total body
weights. Electrolytes, glucose and oxygen.
 Extracellular fluid- Fluid outside of the cells. About 20% of total
body weight. Found in 3 compartments:
 - Interstitial fluid- Spaces between most of the cells of the body
15% of total body weight.
Intravascular fluid or plasma- In the arteries, veins and
capillaries. About 5% of body weight.
Transcellular fluid- cerebrospinal fluid, urine, digestive
secretions, perspiration and small amounts of fluid found within
organs and joints. Less than 1% of body weight.
ECF- Transports oxygen and nutrients to cells and waste away.
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Distribution
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Electrolytes are found in both fluid compartments, although the
concentration or amount of individual electrolytes in the ICF and
ECF differs.
Na+, chloride (CL), and bicarbonate (HCO3) are plentiful in
extracellular fluid.
Potassium (K+), magnesium (Mg+), and phosphate
(PO4) are plentiful in the intracellular fluid.
The cell membrane and capillary walls separate the body
fluid compartments. Water and solutes move across these
membranes by the processes of osmosis, diffusion,
filtration and active transport.
Membrane Transport Processes

Osmosis - water moves across a
membrane that is permeable to water
but not to solutes,
Osmosis
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Osmosis is responsible for water
movement between the ICF and ECF
compartments.
Water moves toward a higher solute
concentration!
Membrane Transport Processes
Diffusion - when molecules move from an area of high
concentration to an area of low concentration to become
evenly distributed
Diffusion

Molecules move across a
semipermeable membrane from an area
of higher solute concentration to an
area of lower concentration.
Filtration
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Process in which water and solutes move across
capillary membranes driven by fluid pressure. This
pressure is created by the pumping action of the
cardiac muscle and gravity.
A balance between filtration and osmosis regulates
the movement of water between the intravascular
and interstitial spaces in the capillary beds of the
body.
Membranes are selectively permeable, they allow
water and some solutes o2, co2, electrolytes and
glucose to cross. Block proteins and large molecules.
Membrane Transport Processes
Active transport - molecules are moved, carried across a cell
membrane, usually large water soluble molecules - glucose
Regulatory Mechanisms
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Thirst - primary regulator of water
intake, fluid balance prevent dehy.
Kidneys - Renin-AngiotensinAldosterone Mechanism
– regulate fluid volume and electrolyte
balance

Antidiuretic Hormone Mechanism (ADH)
– secreted by pituitary, acts on kidney to
increase water absorption, decrease.
Regulatory Mechanisms
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The kidneys, by selectively reabsorbing
water and electrolytes maintain the
volume and osmolality of body fluids.
Renin-Angiotensin-Aldosterone
System-Maintains the intravascular fluid
balance and blood pressure.
Antidiuretic Hormone- Regulates water
excretion from the kidneys.
Renin-Angiotensin-Aldosterone
System
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A fall in blood flow to the kidneys (decreased fluid
volume), stimulates receptors in the kidney to
produce renin (an enzyme). Renin coverts
angiotensinogen in the blood into angiotensin one.
The lungs then convert angiotension one to
angiotension two by ACE.
Angiotension TWO constricts blood vessels which
raises blood pressure, it also stimulates thirst,
releases aldosterone from the adrenal cortex and
acts directly on the kidneys, causing them to retain
sodium and water, thus restoring blood volume.
Antidiuretic Hormone
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Regulates water excretion from the kidneys.
Receptors in the hypothalamus detect changes in
osmolality and blood volume stimulating ADH
production and release as needed.
When ADH is present more water is reabsorbed in
the kidney; urine output falls, blood volume is
restored and serum osmolality drops as the water
dilutes body fluids.
See disorders: diabetes insipidus, inappropriate ADH
secretion (SIADH).
Thirst
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The thirst center in the brain is stimulated when the blood
volume drops because of water losses or when the solute
content of body fluids increases.
The thirst mechanism declines with age, so older adults are
more vulnerable to dehydration.
Clients with impaired consciousness or who are unable to
respond to thirst also are at risk
Osmosis and fluid volume
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Isotonic solutions such as normal saline 0.9% sodium
chloride solution have the same concentration of
solutes as blood plasma. Cells placed in an isotonic
solution do not gain or lose water.
Hypertonic solutions such as 3% sodium chloride
solution have a greater concentration of solutes than
plasma. A cell placed in a hypertonic solution shrinks
as water is drawn out of it into the solution.
Hypotonic solutions such as 0.45% sodium chloride
have a lower solute concentration than plasma. A cell
placed in a hypotonic solution swells as water moves.
Dehydration - Fluid Volume
Deficit
The Client With Fluid Volume
Deficit
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Patho - excessive fluid losses,
insufficient fluid intake or a combination
of both; vomiting, diarrhea or GI suction.
Multisystem effects
– Neurological
– Integumentary
– Cardiovascular
• hypotension
– Urinary
– Musculosketel
Fluid Volume Deficit
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Interdisciplinary Care
– Fluid Challenge
• obtain base line vs, give fluid bolus, re-eval vs
– IV solutions
• isotonic - .9% n.s. or Ringer’s Lactate tx
hypotension
• hypotonic - .45% n.s. - maintenance solutions
Nursing Care: Fluid Volume
Deficit
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Assessment of factors contributing to
abnormal fluid loss
Assess intake and output, daily wt
Assess vital signs
– hypotension and tachycardia
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Assess for dehydration
Adm. po and IV fluids
Assess labs: LOC, Urine output
Fluid Volume Excess

Fluid volume excess
– overhydration - excess intake
– excessive sodium intake
– disease process; CHF, liver cirrhosis
• Kidney failure, drugs Na retention, high Na
foods, Na containing fluids

Clinical Manifestations
– Tachycardia, bounding
pulse,tachypnea,crackles in lungs
– Of edema fluid into sub Q tissue- eyes,dep.
Clinical Manifestations

Respiratory
– cough
– SOB, crackles and wheezes, orthopnea
– pleural effusion

Cardiovascular
– elevated B/P, full and bounding pulses
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Abdominal
– ascities
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Neurological- Fatigue, altered LOC
Pulmonary edema
What has happened here?
Nursing Care: Fluid Volume
Excess
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Assessment - I & O, V.S. heart sound
S3 (gallop), daily wt
Administer fluids cautiously
Client teaching
– sodium and fluid restriction- Na retention.
– meds and side effects
– signs of fluid retention
– symptoms to report
Electrolytes
Electrolyte Disorders -Sodium
Na+ 136 - 148 normal range
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Hyponatremia - sodium level; Acid Base
<136mEq/L. Maintains ECF volume, bal
Causes
– burns, excessive sweating, G.I. losses
– diuretics, Addison’s disease, renal disease
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Treatment
– .9% N.S. 3%N.S
– loop diuretics
– fluid restriction
Electrolyte Imbalances
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Hypernatremia - > Na+ 148mEq/L
Causes
– too much Na+ in excess water
– loose too much water and not enough
sodium

Treatment - correct slowly over 2 days
– D5W or .45% N.S. hypotonic soln to
correct water deficit
– low Na+ diet
K+
packs a punch
primary intracellular cation. Vital
Electrolyte Disorders - Potassium
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K+ 3.5 to 5.0 mEq/L normal range
vital intercellular cation - helps
determine cell contractility nerve and
muscle cells, must be replaced
Every day!
Hypokalemia - K+ <3.5
– Causes
• urinary loss
• G.I. loss
Potassium imbalance

The kidneys eliminate potassium very
efficiently; even when potassium intake
is stopped, the kidneys continue to
excrete potassium.

Thus potassium must be replaced every
day!!!All foods contain K+, some more
plentiful than others. Which ones?
Electrolyte Disorders:
hypokalemia
– Clinical Manifestations
•
•
•
•
neuro- decrease in reflexes
cardio - dysrhythmias, cardiac arrest
G.I. - n/v, anorexia, diarrhea
musculosketel - weakness, leg cramps
– Treatment
• K+ replacement
– oral - need to dilute
– parental - DILUTE ALWAYS, pain at site, pump
dilute in IV fluids Is a must; or death!!!!!!!!!!!!!!
Electyrolyte Disorders:
Hyperkalemia
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K+ >5mEq/L
Causes
– inadequate excretion of K+ - Renal
disease
– Excessive intake of K+ - K+ sparing
diuretics, salt substitutes

Clinical Manifestations
– Neuromuscular activity - tremors, twitching
– Cardiac - dysrhythmias
Electrolyte Imbalance:
hyperkalemia

Treatment
– potassium loosing diuretics - lasix
– Insulin - D50 - sodium bicarb
• causes K+ to shift back into the cells
– Kayexalate - exchange resin (Na+ and
Ca+)
• oral, NGT, enema
– Sorbitol - promote bowel elimination
Fluid Balance, Lets Review

What are the causes of “Fluid Volume
Deficit?”

Clinical Manifestations?
– Neuro?
– Urinary?
Integ? Cardiovascular?
Muscular/skeletal?
Fluid Volume Excess

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What are the causes of “Fluid Volume
Excess?”
What are the clinical manifestations?
– Respiratory?
– Cardiovascular?
– Abdominal?
– Neurological?
Nursing Care - Fluid Volume
Excess
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What should you assess for? What
might you find?
What should you teach and why?
Electrolyte Disorders
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Hypokalemia K+ < 3.5
What are some of the causes?
Clinical Manifestations?
– Neuro?

Cardio?
Treatment?
G.I.? Musculo/skel?
Electrolyte Disorders
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Calium Disorders
Ca+ 8.8 - 10.0mg/dL normal range
– hyper and hypocalcemia
– secondary to other disease processes
– Hypercalcemia
• hyperparathyriodism - thyroid tumor, bone CA
– Hypocalcemia
• hypoparathyriodism, parathyroid surgery
Electrolyte Disorders
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Phosphorus
PO4 2.5 - 4.5mg/dL
– Hypophosphatemia
• TPN, high concentrated glucose soln
• GI loss, ETOH withdrawal
– Hyperphosphatemia
• Renal failure - builds up in blood stream
Electrolyte Disorders

Magnesium Mg+ 1.3 - 2.1mEq/L
– Hypomagnesium
• ETOH abuse
• GI disorders -impaired absorption-diarrhea
• Diuretics
– Hypermagnesemia
• Renal Disease
Acid base balance
Acid-Base Balance
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For optimal cell function acid base balance must
remain within the normal pH range of 7.35-7.45. 7 is
neutral.
Thus this would imply that the ratio of bicarbonate to
carbonic acid is about 20:1.
The hydrogen ion concentration of a solution is
measured as its pH.
As hydrogen ion concentration increases the pH falls,
and the solution becomes more acidic.
As hydrogen ion concentration falls, the pH rises, and
the solution becomes more alkaline or basic.
Acid Base
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Acids are continually produced by metabolic processes in the
body.
Two types of acids
1. Volatile – Which can be eliminated as a gas. Co2
2. Nonvolatile- Must be metabolized or excreted from the body
in fluid. Hydrochloric acid, lactic acid, phosphoric acid.
Three systems in the body work together to maintain a normal
pH despite continuous acid production: Buffers system,
respiratory system, and renal system.
Normal pH systems
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Buffer- Chemicals that prevent major changes in pH by
attaching to or releasing hydrogen ion. (hemoglobin, plasma
proteins, inorganic phosphates)
Respiratory system- Regulates carbonic acid in the body by
eliminating or retaining carbon dioxide. Acute increases in either
carbon dioxide or hydrogen ions in the blood stimulate the
respiratory center in the brain to increase the rate and depth of
respirations. This eliminates carbon dioxide from the body;
carbonic acid levels fall and the pH goes to a normal range.
Occurs within minutes; becomes less effective over time.
Alkalosis (pH above 7.45) depresses the respiratory center, the
rate and depth of respirations decrease and co2 is retained
Patients with chronic lung dx may have high co2 levels in blood
Normal pH systems
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Renal system- responds slowly(hrs to days). Longe
term regulation of acid-base balance.
The kidneys regulate bicarbonate levels in the ECF
and can either excrete or retain hydrogen ion as
needed.
When excess hydrogen ions are present and the pH
falls, the kidneys excrete hydrogen ions and retain
bicarbonate.
When bicarbonate levels are high(pH incr) the
kidneys retain hydrogen ion and excrete bicarbonate
to restore acid-base balance.
Assessment of Acid Base
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Acid-base balance is evaluated by measuring arterial blood gas.
ABG’s
Elements Measured:
PaCO2, PaO2, bicarbonate and the pH.
Arterial blood is used because it reflects acid-base balance
throughout the body and allows evaluation of oxygenation.
Pressure for at least 5 minutes after lab draw. RN, respiratory
therapist or lab tech with specialized training. Arteries are high
pressure vessles.
ABG’s are analyzed to identify acid-base disorders and their
probably cause, extent of the imbalance, monitor treatment.
Acid -Base Definitions
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Acid - a molecule that can contribute a
hydrogen ion
Base - a molecule that can accept or
remove a hydrogen ion
Buffer - substance that controls
hydrogen ion concentration in a soln by
absorbing H+ when acid is added or by
releasing H+ when base is added
Acid- Base Disorders
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Hydrogen Ion concentration pH 7.35 7.45
Classification of Acid-base Disorders
– Acidosis - pH <7.35
– Alkalosis - pH >7.45
– metabolic - buffer system releasing bicarb
– respiratory - control hydrogen ion
concentration by controlling resp rate
Metabolic Acidosis
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Causes
– severe diarrhea
– renal disease
– untreated diabetes
– starvation
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Treatment - fix underlying cause
– bicarbonate - IV or PO
– Resp increase rate and depth of respiration
Metabolic Alkalosis
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Causes
– Vomiting, loose acid.
– diuretics
– too much sodium bicarb

Treatment
– fix the underlying cause
– oral K+ supplements
Respiratory Acidosis

Causes: pH less than 7.35
– any condition that impairs gas exchange,
pneumonia, COPD, chronic bronchitis
• CO2 is retained, chest trauma
– rapid shallow breathing
– hypoventilation -brain stem injury, drug OD

Treatment
– Respiratory support - 02 - breathing tx ventilator
Respiratory Alkalosis

Causes: pH greater than 7.45
– hyperventilation
• asthma, high altitude
• excessive mechanical ventilation; Hyperven.
• anxiety attack
– CO2 deficiency secondary to hyperventilation

Treatment
– breath into paper bag
– re-breath CO2
Diagnostic Tests Acid Base
Balance
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Sodium (Na)- 135-145 mEq/L
Potassium (K+)- 3.5-5.3 mEq/L
Calcium (Ca)- 4.5-5.5 mEq/L
Magnesium (Mg+)- 1.5-2.5 mEq/L
Chloride (CL-)- 95-105 mEq/L
Bicarbonate (HCO3)- 24-28 mEq/L
Phosphate/Phosphorus- 1.7-2.6 mEq/L
Serum Osmolality- 280-300 mOsm/kg
Urine Specific Gravity – 1.005-1.030
NCLEX
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The primary electrolyte that controls the
water balance in the body is:
A. Na
B. K
C. chloride
D. magnesium
NCLEX
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Mr. Smith has recently been diagnosed with a kidney
dysfunction. He constantly complains of thirst.
Which of the following statements to the client best
indicates the nurse’s understanding of the thirst
mechanism?
A. “Thirst is the primary regulator of water intake.
When we are thirsty we drink.”
B. “Thirst is important in maintaining fluid balance
and preventing dehydration.”
C. “Thirst mechanisms decline with age, making the
older adult at risk for dehydration.”
D. “ A drop in blood volume stimulates the thirst center in the
NCLEX
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The mechanism of action for the antidiuretic hormone (ADH)
may be defined as:
A. kidneys reabsorb more water when the hormone is present
B. kidneys cease urine production when the hormone is present
C. blood osmolality increases as urine output decreases
D. the hypothalamus detects increased osmolality of the blood
and stimulates the release of ADH.
NCLEX
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Alice is a 2-year-old who has been suffering from vomiting and
diarrhea for three days. Temperature is 102 f and she appears
lethargic and exhausted. Her mother reports that Alice has not
been able to keep anything down. Based on this information,
Alice’s primary nursing diagnosis should be:
A. Activity intolerance
B. Deficient fluid volume
C. Altered nutrition: Less than body requirements
D. Risk for diarrhea
NCLEX
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Which electrolyte is most readily
excreted by the kidneys and will be lost
even when other electrolytes are
conserved?
A. K+
B. sodium
C. Magnesium
D. Calcium
NCLEX
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Which of the following statements is FALSE regarding the acidbase balance system?
A. Blood buffers react quickly but are limited
B. The respiratory system adjusts the acid-base balance by
either slowing or increasing respirations
C. The renal system is the slowest of the systems but is
responsible for long-term balance
D. When hydrogen ions and the pH in the blood increase, the
result is acidosis
NCLEX
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A client suffering from metabolic acidosis is most
likely to:
A. experience an increase in the blood pH
B. develop tachypnea
C. recover slowly, due to the kidney’s role in acidbase balance
D. be diagnosed with acute pneumonia
NCLEX
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Mr. Jacobs who was diagnosed with COPD 5 years ago has
been using his oxygen at home via nasal cannula. The flow rate
is set at 2L/minute. Mr. Jacobs respirations are 28/minute and
her complains of SOB after minimal exertion. His wife is
concerned that the amount of oxygen is “too low”. Your best
response should be:
A. I can’t change the flow rate without an order.
B. Okay, let’s increase the flow rate to 6L/minute and see how
he does.
C. increasing his oxygen may actually block his respiratory
center in the brain.
D. I will call the provider and let them know about your concerns