Fluid and Electrolytes: Balance and Disturbances Jimmy Durbin, MSN, RN.
phathophysiology2(Water and Electrolytes balance and imbalance)
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Transcript of phathophysiology2(Water and Electrolytes balance and imbalance)
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Contents
Disorders of Water & sodium metabolism
Disorders of potassium metabolism
Disorders of magnesium metabolism
Disorders of calcium & phosphorus
metabolism
After completing this chapter, you should be able to
Describe mechanisms which maintain normal water and sodium balance
Predict changes in the volume and osmolality of the fluid compartments in response to gain or loss of water or Saline
Explain the pathogenesis and consequences of hypotonic and hypertonic dehydration
Outline the basic mechanisms of edema
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Water balance
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2.1
Water and Sodium Balance
Distribution of body fluid(BF)
BF 60% plasma 5%
Interstitial fluid 15%
ICF 40%
ECF 20%
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Electrolyte in BF
ClNa Na Cl K
HPO4
plasma
Interstitial fluid
ICF
KCa Mg
KCa Mg
HCO3
HPO4
HCO3
HPO4
HCO3
SO4SO4SO4
PrPrOrganic
acid
Organic acid
Na
Ca
Mg
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Multiple choice questions of type A
The major cation in plasma is
A.Na+ B.K+
C.Ca2+ D.Mg2+
E.Fe2+
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Osmolality↑
Osmolality↓H2OH2O
H2OH2O
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Osmolality of BF
•Directly related to the concentration of solutes in the solution•The higher the solute concentration, the greater the osmotic pressure and the greater the tendency of water to move into the solution
Normal OPP = cation(151) + anion(139)
+ nonelectrolyte (10)
= 300mmol/L(280 ~ 310mmol/L)
(A) Addition of water to the
body
(B) Addition of hypertonic
salt solution
(C) Addition of isotonic salt
solution
(D) loss of sodium chloride
E I E I
E I E I
Volume
conce
ntra
tion
A B
C D
Changes in volume and osmolality of intracellular(I) and
Extracellular
(E) fluids.
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Regulation of Water & Sodium Balance
Water balance
Sodium balance
Regulation of Volume &
Osmolality of BF
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Water balance
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Sodium (Na +)
most abundant cation in ECF
creates osmotic pressure of ECF
N=130-150 mmol/L
essential for electrical activity of
neurons and muscle cells
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Sodium balance
Intake: 100-200 mmol/day
Output : urine, sweat
Sodium balance is regulated by
kidney
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Volume & Osmolality regulation of BF
variation of BF vol
variation of OPP
ADH
aldosterone
ANP
Thirst center
ADH
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Regulation of Water Intake
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Regulation effects of ADH (antidiuretic hormone)
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Renin-Angiotensin-Aldosterone System
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summary
water volume sodiumosmolality
Thirst center
↑Intake ↑ -↓
ADH ↓Output ↑ - ↓
RAAS ↓Output ↑ ↑reabsorption normal
ANP ↑output ↓ ↓ reabsorption normal
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2.2
Disorders of Sodium and Water Metablism
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volume
Serum sodium concentrationHyponatrem
ia<130mmol/
L
hypernatremia >150mmol/L
Normal
hypovolemichypovolemic Hyponatremi
a
hypovolemic hypernatremia
Isotonic dehydration
hypervolemic
hypervolemic Hyponatremia
hypervolemic hypernatremia
edema
nomovolemic
nomovolemic Hyponatremia
nomovolemic hypernatremia
normal
Classification of H2O & Na disorders
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hyponatremia
serum sodium < 130 mmol/L ↓ ECF Osmolality < 280 mmol/L ↓ thirsty ↓ ADH ↓ water redistribution ↓ ↓ ↓ intake↓ output↑ cellular swelling
ECF Osmolality ↑volume ↓
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Ture or false
Hyponatremia=loss of sodium?
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hyponatremia
hypovolemic hyponatremia
hypervolemic hyponatremia
nomovolemic hyponatremia
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hypovolemic hyponatremia (hypotonic dehydration)
Definition
Causes & mechanism
Effects
Principles of therapy
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sodium loss > water loss
serum sodium < 130 mmol/L
OPP < 280mmol/L
Definition
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Causes & mechanism
renal loss ex- renal lossDiuretics
Adrenal insufficiency
Renal disease
renal tubule acidosis
Renal output of Na
and H2O ↑
GI tract(diarrhea, vomiting
or gastric suction)
Third space (hydrops)
Skin (burn or sweating)
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Effects
OPP
Thirst ↓ →water intake↓ADH ↓ → renal output↑
ICF →ECF↓
ECF
circulatory failure shockBl vol↓ aldo↑→ UNa↓ ADH ↑→oliguriainterstitial fluid↓→sign of dehydration
Caused by renal factors , UNa↑
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Principles of therapy
Treat underlying cause
Restoration the vol of ECF
Treat complication
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Multiple choice questions of type A
loss of BF caused by hypotonic dehydration exists in
A. extracellular fluid B. plasma
C. interstitial fluid D. intracellular
fluid
E. both ECF and ICF
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hypernatremia
serum sodium >150 mmol/L ↓ ECF Osmolality > 310 mmol/L ↓ thirsty ↑ ADH ↑ water redistribution ↓ ↓ ↓ intake ↑ output↓ cell dehydration
ECF Osmolality ↓ volume ↑
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hypernatremia
hypovolemic hypernatremia
hypervolemic hypernatremia
Isovolemic hypernatremia
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hypovolemic hypernatremia (hypertonic dehydration)
Definition
Causes & mechanism
Effects
Principles of therapy
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Definition
water loss > sodium loss
serum sodium >150 mmol/L
OPP > 310mmol/L
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Causes & mechanism
Water intake↓ Water output↑
Unavailability of water
Thirst ↓
Unable to drink
air tube
Skin
kidney
GI tract
ADH secretion↓
diuretics
high protein diet
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Effects
ECF
aldo↑→ oliguriaBl vol↓ ADH ↑→oliguria UNa↑Interstitial fluid↓→sign of dehydration
thirst→water intake↑ ADH ↑ → oliguriaICF ↓ →brain cell dehydration →CNS
disorders
OPP
Twitching, somnolence, respiratory paralysis
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Principles of therapy
Treat underlying cause
Restoration vol of ECF
Adding NS
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Comparison between hypotonic and hypertonic dehydration
hypotonic hypertonic
The thirst sensation ↓ ↑
Urine output ↑ ↓
hypovolemic shock √ +
Effects of CNS - √
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Multiple choice questions of type A
Shock is often caused by which of the following disorder of water and electrolytes
A. hypotonic dehydration
B. hypertonic dehydration
C. isotonic dehydration
D. water intoxication
E. hypokalemia
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2.2 Edema
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Edema
Definition
Pathogenesis of edema
Effects of edema
Principles of therapy
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Definition
Fluid accumulation in the interstitial
compartment
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Types of edema
Extent anasarca local edema causes cardiac edema/renal edema/hepatic edema/
nutritional edema/inflammatory edema/ lymphatic edema
location cutaneous dropsy/brain edema/ pulmonary
edema
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Pitting edema
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nutritional
edema
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Pathogenesis of edema
Imbalance of fluid interchange
across capillaries
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Pathogenesis of edema
the increased renal retention of sodium and water
glomerular Filtration rate ↓
(glomerulopathy /circulation volume ↓)
Augmented filtration fraction(FF)
Release of aldosterone and ADH ↑→Water and
sodium reabsorb in renal tubules ↑
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Effects of edema
Benificial effects Protective effects of inflammatory edema Harmful effects Nutritional disturbance Effects on functions of organs and tissues
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CASE PRESENTATION
An 84-year-old woman was brought to the hospital because she was lethargic and refused to drink. On admission, she weighed 60 kg. Her blood pressure was 100/60mmHg with a pulse of 110 per minute and poor skin turgor. laboratory examination revealed a BUN of 100mg/dl, sodium of 170mEq/L, potassium of 4.0Eq/L, and CO2 of 24mmol/L. serum creatine was
2.5mg/dl. Urinalysis showed a specific gravity of 1.030, no protein, glucose, or acetone was present. urine sodium was 5mEq/L and urine osmolality 726mOsm/L.
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Questions
What kind of disorders of water and sodium metabolism happened to this patient?
What’s the primary reason for the water and sodium imbalance?
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