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CHAPTER 11
IGGY-PG 148-173
Assessment and Care of
Patients with Fluid and
Electrolyte Imbalances
Copyright © 2016, 2013, 2010, 2006, 2002 by Saunders, an imprint of Elsevier Inc.
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Describe basic concepts of fluid and electrolyte balance
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Define ways fluids and electrolytes maintain homeostasis
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Identify nursing interventions to promote fluid, electrolyte
balance and how to correct.
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Describe pathophysiology of selected fluid and electrolyte
imbalances
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Identify key electrolytes and their normal lab values
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Identify considerations related to the older adult
OBJECTIVES
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Proper functioning of all body systems; requires fluid and
electrolyte balance
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Extracellular fluid (ECF)
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Intracellular fluid (ICF)
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Interstitial fluid
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Transcellular fluids
HOMEOSTASIS
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Movement of fluid through cell or blood vessel membrane
because of differences in water pressure (hydrostatic
pressure)
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This is related to water volume pressing against confining
walls
FILTRATION
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“Water-pushing pressure”
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Force that pushes water outward from a confined space
through a membrane
Amount of water in any body fluid space determines
pressure
Example: Blood pressure
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Moving whole blood from the heart to capillaries where
filtration occurs to exchange water, nutrients, and waste
products between the blood and tissues
HYDROSTATIC PRESSURE
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Develops with changes in normal hydrostatic pressure
differences
CLINICAL SIGNIFICANCE:
EDEMA
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Free movement of particles (solute) across
permeable membrane from area of higher to
lower concentration
Important in transport of most electrolytes; other
particles diffuse through cell membranes
Sodium pumps
Glucose cannot enter most cell membranes
without help of insulin
DIFFUSION
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Act together at capillary membrane to maintain normal
ECF and ICF volumes
Thirst mechanism is example of how osmosis helps
maintain homeostasis
Feeling of thirst caused by activation of brain cells
responding to changes in ECF osmolarity
OSMOSIS & FILTRATION
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Closely linked to/affected by electrolyte
concentrations
Fluid intake
Fluid loss
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Minimum urine amount needed to excrete toxic
waste products = 400 to 600 mL/day
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Insensible water loss – Through skin, lungs, stool
FLUID BALANCE
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Aldosterone
Antidiuretic hormone
Natriuretic peptides
https://www.khanacademy.org/science/healthand-medicine/circulatorysystem/blood_pressure_control/v/aldosteroneraises-blood-pressure-and-lowers-potassium
HORMONAL REGULATION
OF FLUID BALANCE
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Blood (plasma) volume and intracellular fluid most important
to keep in balance
Kidneys are major regulator of water and sodium balance;
maintain blood and perfusion pressure to all tissues/organs
When the kidneys sense a low parameter, they secrete renin
Renin-angiotensin II pathway is greatly stimulated with
shock, or when stress response is stimulated
SIGNIFICANCE OF FLUID BALANCE:
RENIN-ANGIOTENSIN II PATHWAY
11
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Disrupt renin-angiotensin II pathway by reducing
amount of ACE produced
With less angiotensin II, less vasoconstriction and
reduced peripheral resistance
Greater excretion of water and sodium in urine
By locking angiotensin II receptors, blood
pressure lowers
Patients with hypertension often take ACEinhibitor medications
ACE INHIBITORS
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Fluid intake/retention does not meet body’s fluid
needs; results in fluid volume deficit
Assessment
History
Physical assessment/clinical manifestations:
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Cardiovascular
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Respiratory
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Skin
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Neurologic
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Renal
DEHYDRATION:
COLLABORATIVE CARE
13
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1 L of water weighs 2.2 lb, equal to 1 kg
Weight change of 1 lb = fluid volume change of
about 500 mL
FACTS TO REMEMBER...
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Assessment
Patient safety
Pulmonary edema
Drug therapy
Nutrition therapy
Monitoring of intake and output (I&O)
FLUID OVERLOAD:
COLLABORATIVE CARE
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Can occur in healthy people as result of changes in fluid
I&O
Can be life threatening if severe; can occur in any setting
ELECTROLYTE IMBALANCE
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Normal level: 136-145 mmol/L
“Where sodium goes, water follows”
Hyponatremia
Hypernatremia
SODIUM
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Normal level: 3.5-5.0 mEq/L
Some control over intracellular osmolarity and
volume
Hypokalemia
Hyperkalemia
POTASSIUM
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Normal level: 9.0-10.5 mg/dL
Absorption requires active form of vitamin D
Stored in bones
Parathyroid hormone
Thyrocalcitonin
Hypocalcemia
Hypercalcemia
CALCIUM
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HYPOCALCEMIA
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Normal level: 3.0-4.5 mg/dL
Found in bones
Activates vitamins and enzymes; assists in cell
growth and metabolism
Plasma levels of calcium and phosphorus exist in
a balanced reciprocal relationship
Hypophosphatemia
Hyperphosphatemia
PHOSPHORUS
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Normal level: 1.3 to 2.1 mg/dL
Critical for skeletal muscle contraction,
carbohydrate metabolism, ATP formation, vitamin
activation, cell growth
Hypomagnesemia
Hypermagnesemia
MAGNESIUM
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Normal level: 98 to 106 mEq/L
Imbalance occurs as a result of other electrolyte
imbalances
Treat underlying electrolyte imbalance or acidbase problem
CHLORIDE
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At risk for most electrolyte imbalances from agerelated organ changes
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Have less total body water than younger adults;
more at risk for fluid imbalances; more likely to
be taking drugs affecting fluid or electrolyte
balance
Extra help/resource:
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https://quizlet.com/51866323/nursing-fluidelectrolyte-flash-cards
CONSIDERATIONS FOR OLDER
ADULTS
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