Transcript Nutrition, Fluid & Electrolytes

Fluid & Electrolytes
FA 08
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Introduction
 Fluid, electrolyte, and acid-base balances
within the body are necessary to maintain
health and function of all body systems
 These balances are maintained by the intake
and output of water and electrolytes and
regulation by the renal and pulmonary
systems.
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 Water is the largest single component of the
body. 60% of the average adult’s weight is
fluid. 1 kg=1L
 A healthy mobile and well oriented adult can
usually maintain normal fluid, electrolyte and
acid/base balance.
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Distribution of body fluids
 Compartments
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Intracellular (ICF)—all fluid within body cells.
Extracellular (ECF)—all fluid outside a cell,
divided into smaller compartments
Interstitial fluid—between the cells and outside the
blood vessels
 Intravascular fluid—blood plasma
 Transcellular—found in the spaces of the GI tract,
cerebrospinal fluid and intraocular space

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Fluid Compartments in the Adult
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Body Water
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ECF check….
 When a person loses
water sweating, the
ECF volume is
decreased
 A message is sent to
the hypothalamus in
the brain
 Thirst center stimulated
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Composition of body fluids
 Water
 Electrolytes—minerals or salts
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Element or compound when melted or dissolved in water
separates into ions and is able to carry an electrical
current
Vital to body function
Value expressed as mEq/L-milli equivalents per liter, is
the number of grams of the specific electrolyte dissolved
in a liter of plasma
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Charge
 Negatively charged electrolytes are
Anions
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Chloride
Bicarbonate
Sulfate
 Positively charged electrolytes are
Cations
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Sodium
Potassium
Calcium
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Composition of body fluids
 Minerals
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Act as a catalyst in nerve response, muscle
contraction, and metabolism of nutrients in foods
Regulate electrolyte balance and hormone
production and strengthens skeletal structures
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Movement of body fluids
 Fluids and electrolytes
constantly shift from
compartment to
compartment to
facilitate body
processes—tissue
oxygenation, acid-base
balance, urine
formation
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Osmosis
 Osmosis—movement of a pure solvent thru a
semipermeable membrane from an area of lesser
solute concentration to an area of greater solute
concentration
 Osmotic pressure—drawing power for water and
depends on number o molecules in solution

Osmolarity—measure used to evaluate serum and urine
in clinical practice
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Osmosis: Water molecules move from
lower to higher concentrations
H2O
H2O
H2O
H2O
H2O
Solutes (Electrolytes)
Water Molecules
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Classification
 Isotonic—same osmolarity as blood plasma

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Expands the body’s fluid volume without
causing a fluid shift from one compartment to
another
0.9% Sodium Chloride = Normal Saline
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Classification
 Hypertonic—a solution of higher osmotic
pressure; pulls fluid from the cell (shrink)
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3% NS
5% NS
D5NS
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Classification
 Hypotonic—solution of lower osmotic
pressure; moves fluid into the cells causing
them to enlarge (swell)
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0.45% NaCl
0.5% NaCl
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Diffusion
 Process during which a solid in a fluid moves
from an area of higher concentration to an
area of lower concentration
 Even distribution
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Regulation of body fluids
 Regulated by fluid intake, hormonal controls,
and fluid output
 Homeostasis—physiological balance
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Fluid intake
 Regulated primarily through the thirst
mechanism
 Thirst control is located in the hypothalamus
 Thirst is the conscious desire for water
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Compensatory Mechanisms: Thirst
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Hormone Regulation
 ADH—antidiuretic hormone
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Water is saved in the kidneys thru the pituitary gland’s
secretion of ADH
 Aldosterone
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Water reabsorption is also regulated by aldosterone
produced by the adrenal cortex, which increases sodium
and water reabsorption in the body and decreases sodium
and water excretion in the urine
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Hormone Regulation
 Renin
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Secreted by the kidney
Responds to decreased renal perfusion secondary to
decrease in ECF
Angiotensin Ivasoconstriction
Angiotensin IImassive selective vasoconstriction
And stimulates release of aldosterone when Na+
concentration is low
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Fluid Regulation
 Kidneys 1200-1500
 Skin 500-600
 Lungs 400
 GI 100-200
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Fluid Regulation
 Kidneys
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Major regulatory organ of fluid balance
Receive approximately 180L of plasma to filter
each day and produce 1200-1500 ml of urine
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Fluid Regulation
 Skin
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Regulated by the sympathetic nervous system,
which activates sweat glands
Water loss from skin can by sensible or
insensible
Insensible—continuous/not perceived
 Sensible—through excess perspiration

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Fluid Regulation
 Lungs
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Change with rate and depth of respirations
 GI Tract
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3-6L of isotonic fluid is moved into GI tract and then
returns again to the extracellular fluid
Average loss is 100-200 ML of the 3-6L each day thru
feces
Diarrhea, GI tract may become a site of a large amount
of fluid loss.
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At risk population
 Infants, clients with
neurological or psychological
problems and some older
adults who are unable to
perceive or respond to the
thirst mechanism are at risk for
dehydration.
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Fluid & Electrolyte Homeostasis In Older Adults
Older Adults
 As percentage of body water decreases, less water is
present in interstitial spaces thus at risk for F&E
imbalances
 Renal changes associated with aging include a 50%
decrease in blood flow through kidneys (decreased
cardiac output) thus causing decreased ability to
concentrate urine and F&E imbalances
 Note, too, that elderly clients are at risk for dehydration
and F&E imbalances due to decreased oral intake of the
same
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Fluid & Electrolyte Homeostasis In Adults
Adults
 Young and middle adults have very responsive
regulatory mechanisms (aldosterone/ADH)
 Least susceptible to F&E imbalances due to ability to
evaluate own fluid needs
 Pregnant women are one exception: Increased blood
volume (30-50% near term) is associated with increased
aldosterone section which causes Na+ to be reabsorbed
and water retention, increased cardiac output is usually
able to keep swelling down (30% of preg. women
experience swelling)
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 Hypovolemia—loss of fluid (excess
vomiting, hemorrhage)
 Dehydration
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Skin turgor
Dryness of lips or oral cavity
Decreased daily intake of fluids
Concentrated urine (elevated specific gravity)
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Hydration Assessment
Hypovolemia
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Postural hypotension
Weight change 2-5% loss
Tachycardia
Dry mucous membranes
Poor skin turgor
Burns, diarrhea, diabetes, vomiting,
sweating, diuretics, laxatives
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Dehydration
 Water loss results in tachycardia
 Lowering of BP
 Decreased cardiac output
 Weakness
 Confusion/disorientation/personality changes
 Check labs
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Hemoconcentration of RBCs
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Hydration Assessment
Hypervolumia
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Excess water gain
Heart failure
Renal failure
High salt intake
Pancreatitis
Rapid weight gain, edema, HTN,
polyuria, NVD
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Interventions for Fluid
Overload
 Restrict intake
 Daily weight
 I & O record—divide fluids
 Oral care
 Education what is considered intake

Ice chips, gelatin, ice-cream
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Regulation of Electrolytes
 Cations + charge

Na
Most abundant cation
 Maintain water balance thru efforts on serum
osmolality, nerve impulse transmission, regulation of
acid-base balance

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Regulation of Electrolytes
 K+ Potassium
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Major electrolyte and principle cation in intracellular
compartment
Regulates metabolic activities
Necessary for glycogen deposits in liver and skeletal muscles,
nerve impulse transmission and conduction, normal cardiac
conduction and skeletal and smooth muscle contraction
Dietary intake/renal excretion
Release with injury
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 Calcium
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Stored in bones, plasma, and body cells (99% is
located in bones)
Necessary for bone and teeth formation, blood
clotting, hormone secretion, cell membrane
integrity, cardiac conduction, transmission of
nerve impulses and muscle contraction
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 Mg2+ Magnesium
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Essential for enzyme activities, neurochemical
activities, and cardiac and skeletal muscle
excitability
Regulated by dietary intake, renal mechanisms,
and actions of parathyroid hormone
50-60% in bone
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Anions
 Chloride
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Regulated by dietary intake and kidneys
 Bicarbonate
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Chemical buffer
Essential for acid-base balance
Regulated by kidneys
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 Phosphate
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Buffer in ECF
Acid-base
With Ca= develop and maintain bones/teeth
Neuromuscular action
GI tract
Diet, renal, intestinal
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Lab Values
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Know the ranges and abbreviations
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Phosphate
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Electrolyte Imbalance
 Na
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Hyponatremia—neuro, tachy, hypo
Hypernatremia—mucous membranes dry
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Flushed skin, thirst
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 K Potassium
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Hypokalemia decreased muscle tone, ventricular
dysarrhythmias and cardiac arrest
Hyperkalemia cardiac arrest, QRS widens, heart
block, bradycardia
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 Mg Magnesium
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Hypomagnesemia—muscle tremors, hyperactive
Deep Tendon Reflexes
Hypermagnesemia—hypoactive DTR’s, low BP,
decreased RR
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 Ca Calcium
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Hypocalcemia—muscle cramps, numbness and
tingling of fingers and tetany
Hypercalcemia—anorexia, lethargy, decreased
LOC
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Chovosteks
 Contraction of facial muscles with facial
nerve is tapped

Tetany, muscle cramps and muscle tremors,
dysrhythmias
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Trousseau
 Carpopedal spasm with hypoxia
 Seen with hypocalcemia or hypomagnesia
Muscle tremors, dysrhythmias, etc
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Specific Gravity
 Urine 1.010-1.025
 Weight of a substance compared to the
weight of an equal amount of water
 H2O specific gravity is 1.0
 Urine 95% water
5% solids
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Regulation of Acid-Base Balance
Chemical:
Biological:
Physiological
:
Occurs when
Carbonic acid
and
hydrogen ions
bicarbonate
are absorbed
buffer system or released by
cells
Buffers are
located in
lungs and
kidneys
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Disturbances in Electrolyte, Fluid,
and Acid-Base Balances
Electrolyte:
Fluid:
Acid-Base:
 Hyponatremia
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Hypernatremia
 Hypocalcemia
 Hypercalcemia
 Hypomagnesemia
 Hypermagnesemia
 Hypochloremia
 Hyperchloremia

Isotonic
 Osmolar
Respiratory
acidosis
 Respiratory
alkalosis
 Metabolic
acidosis
 Metabolic
alkalosis
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IV Therapy
 Crystalloids
 Vascular access devices
 Types of solutions
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IV Therapy
 Crystalloids
 Vascular access devices
 Types of solutions
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Blood Replacement
Colloids
 Plasma
 RBCs
 Platelets
 Blood group types
 Blood transfusions
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