FLUID, ELECTROLYTE,
AND ACID-BASE BALANCE
NUR 102 - Chapter 14
Body fluids
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Extracellular fluids (ECF)
• Interstitial fluid - fills the spaces between most
•
cells of the body
Intravascular fluid - plasma (WBC, RBC and
platelets in this fluid)
Body fluids
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Intracellular fluids (ICF)
• Liquids within cell membranes
• 40% of body weight
Components in body fluids
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Electrolyte
• an element that when dissolved can carry an
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•
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electrical current
Cations - (+) ; Anions - (-)
neuromuscular function
acid-base balance
Components of body fluids
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Minerals
• ingested compounds
• serve as catalysts in nerve response, muscle
contraction, and metabolism of nutrients in
foods, regulate electrolyte balance
Movement of body fluids
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Diffusion
• Area of higher concentration to an area of
lower concentration till even distribution
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Osmosis
• Movement of a pure solvent, e.g. water
through a semipermeable membrane from a
solution that has a lower solute concentration
to one that has a higher solute concentration
Osmotic pressure
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Drawing power of water (dependent on
the number or molecules in solution)
• Isotonic
• Hypotonic
• Hypertonic
Movement of body fluids
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Filtration
• Water and diffusible substances move
together in response to fluid pressure
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Active transport
• Requires energy
• Able to move larger molecules and go from
less to greater concentration
Fluid Intake
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Hypothalamus - thirst control center
Oral fluid intake requires an alert state
Osmoreceptors - monitor osmolality
Fluid Output
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Loss through the kidneys and GI tract
Insensible
Sensible
Cations
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Sodium (Na+)
• Most abundant in the extracellular fluid
• Maintains water balance, transmits nerve
•
impulses, contracts muscles
Values - 135-145 mEq/L
Cation
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Potassium (K+)
• Major intracellular cation
• Regulates neuromuscular excitability,
•
muscular contraction, and acid-base
Value - 3.5 -5.3 mEq/L
Cation
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Calcium (Ca2+)
• Cardiac conduction, blood
•
coagulation, bone
growth and formation, & muscular relaxation
Value - 4 - 5 mEq/L
Cation
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Magnesium (Mg2+)
• Second most important of intracellular fluids
• Enzyme activities, muscular excitability
• Value - 1.5 - 2.5 mEq/L
Electrolyte Imbalances

Hyponatremia
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Hypernatremia
• GI losses, sweating, & diuretics
• S/S: N/V/D, abd cramps, personality change
• Ingestion of large amounts
• S/S: Dry tongue and mucous membranes,
restlessness, convulsions, thirst, dry skin
Electrolyte imbalances
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Hypokalemia
Causes: K+ wasting diuretics
N/V/D
polyuria
S/S: weak, irregular pulse
• hypotension
• weakness
Electrolyte imbalances

Hyperkalemia
• Causes: Renal failure
• S/S: irregular slow pulse, weakness, irritability
Electrolyte Imbalances

Hypocalcemia
• Causes: Vitamin D deficiency
• S/S: Numb and tingling fingers and circumoral
region, muscle cramps
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Hypercalcemia
• Causes: osteoporosis, prolonged
•
immobilization
S/S: decreased muscle tone, weakness,
lethargy, kidney stones
Electrolyte imbalances

Hypomagnesemia
• Causes: malnutrition and alcoholism polyuria
• S/S: muscular tremors, hyperactive deep
tendon reflexes
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Hypermagnesemia
• Causes: Renal failure
• S/S: hypoactive deep tendon reflexes, shallow
and slow respirations
Acid - Base Balance
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Blood pH - 7.35 - 7.45
paCO2 - 35 - 45
Bicarbonate (HCO3) - 22-26 mEq/L
Respiratory Acidosis
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pH < 7.35
paCO2 > 45 mm Hg
Causes: Respiratory failure
Hypoventilation
Resp muscles paralysis
Airway obstruction
Respiratory Alkalosis
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pH > 7.45
paCO2 < 35 mm Hg
Causes: excessive exhalation of CO2
(hyperventilation)
Metabolic Acidosis
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pH < 7.35
bicarbonate - < 22 mEq/L
Causes: Starvation, DKA, Diarrhea, drug
use
Metabolic Alkalosis
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pH > 7.45
bicarbonate > 26 mEq/L
Causes: excessive vomiting, prolonged
gastric suctioning
Fluid & Electrolyte Imbalances
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Burns - body fluid loss
Renal D/O - abnormal retention of Na,
Cl, K
GI Disturbances - Loss of fluid,
potassium, and chloride
Exercise
S/S electrolyte imbalance
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Head: irritability
Fontanels: depressed, bulging
Eyes: sunken
periorbital edema
Mouth: mucous membranes
CV: neck veins, edema, blood pressure
Resp: Crackles
Imbalances
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GI: abdomen, V/D
Renal: Oliguria or anuria (FVD, FE)
Diuresis (FVE)
Increased urine spec. gravity (FVD)
Skin (Temp)
• increased - met acidosis, hypernatremia
• decreased - FVD
Replacement of fluids and
electrolytes
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Types of IV fluids
Isotonic
Hypertonic
Hypotonic
IV complications
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Infiltration

Phlebitis
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Fluid overload
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Bleeding
• IVF enter SQ space
• vein inflammation
• S/S: pain, redness, warmth
• Fluids given too rapidly
Discontinuing an IV
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Stop infusion
Remove tape
1 - 2 minute pressure
Blood transfusions
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Large bore catheter (18 ga or larger)
Give with normal saline
Baseline vital signs
Double check with two RNs
Begin transfusion slowly
Observe closely for first 15 min
Transfusion Reactions
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Caused by:
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Treatment: stop transfusion, give NS,
save tubing, prepare for emergency
drugs
• blood incompatibility
• allergic sensitivity
• S/S: fever, chills, rash, hypotension, shock