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FLUID, ELECTROLYTE
AND
ACID-BASE IMBALANCES
CHAPTER 18
pages 204-222
WATER within the body
• INTRACELLULAR
– Fluid located inside the cell (35-40%)
• EXTRACELLULAR
– Fluid located outside the cell (15-20%)
• Two types of EXTRACELLULAR
• Interstitial: Fluid between cells (10-15%)
• Intravascular: Fluid in the plasma portion
of blood vessels(5%)
Adult fluid averages
• In healthy adults: average
• daily fluid intake is about
• 2500ml/day
• 100ml/kg of 1st 10kg/wt
• 50ml/kg of 2nd 10kg/wt
• 15ml/kg of remaining kg/wt
• Range of 1800-3000
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Primary source of body fluid
•Food
•Liquids
Fluid & Electrolyte Regulation
• Normal conditions: these things maintain normal fluid volume & electrolyte concentrations:
– Osmoreceptors: Release of Antidiuretic Hormone (ADH)
– Renin-Angiotensin-Aldosterone System
– Secretion of Atrial Natriuretic Peptide (ANP)
Osmoreceptors
• Definition: neuron that senses serum osmolality
• Serum Osmolality: measurement of the concentration of substances in the blood.
•
• Regulation of fluid volume
• Located: Hypothalmus
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Baroreceptors
• Similar to osmoreceptor except it deals
with the blood volume in the heart to
detect changes in blood volume and blood
pressures
• Found in the aortic arch and carotid sinuses
• Definition: Trigger ADH when blood volume
decreases by 10% or BP drops below 90 or
the right atrium is not filling up
RENIN-ANGIOTENSIN-ALDOSTERONE
SYSTEM
• This system is a chain reaction
of chemical being released to increase
both BP and blood volume
• Trigger: juxtaglomerular apparatus
– Ring of cells that surround the arterioles
leading to each glomerulus in the kidney
How does it work?
• Low volume detected…such as blood loss.
• Triggers the juxtaglomerular to release renin
• Renin causes formation of angiotensinogen to angiotensin I and II which causes vasoconstriction and raises BP
• Renin also stimulates the release of aldosteronewhich causes the kidneys to reabsorb sodium causing an increase in blood volume and BP
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Aldosterone
• “The most biologically active mineralcorticoid hormone secreted by the adrenal cortex. Aldosterone increases sodium reabsorption by the kidney, thereby indirectly regulation blood levels of potassium, chloride, and bicarbonate, as well as pH, blood volume, and blood pressure”.
Taber’s Cyclopedic Medical Dictionary
Natriuretic Peptides
• Definition: Hormone-like substance that acts opposite of the renin-angiotensin-aldosterone system
• 3 types identified:
– Atrial natriuretic peptide (ANP)
– Brain natriuretic peptide (BNP)
– C-type natriuretic peptide (CNP)
How does it work?
• If there is too much volume… the atrial and ventricular walls will stretch larger than normal…this triggers the peptides and causes the inhibition of the renin-angiotensin-aldosterone system and ADH
• This causes an increase in urine production to get rid of the excess sodium that has been retained .
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Fluid & Electrolyte Distribution
• Osmosis
• Filtration
• Diffusion
• Active Transport
Osmosis
• Defined: the movement of
water through a semi-permeable
membrane (one that allows some but
not all substances to pass through)
• Goes from diluted areas to less
diluted areas
Key Terms
• Semi-permeable: Characteristic of cell membranes that permit the passage of some material, but not all….
• Membrane: A thin layer of tissue that lines a tube or cavity, covers an organ or structure, or separates one part from the other.
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Filtration
• Defined: moves fluid and some
substances through a semi-permeable
membrane in order to equalize
pressure differences
Diffusion
• Passive: Substances move from
an area of high concentration to
low concentrated area
• Similar to osmosis in that once things
equal out…things remain constant.
Diffusion
• Facilitated: Certain substances
need assistance from a carrier in
order to pass through the
membrane.
• Example: insulin facilitates (carries)
glucose molecules inside cells
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Active Transport
• Define: requires adenosine triphosphate (ATP) to move substances from area of low concentration to area of higher concentration
• Exact opposite of passive transport
• Example: potassium-sodium pump
Fluid Imbalances
• Basically…for some reason, fluid in the body is not in the proper place or has the correct volume in the proper place.
»Hypovolemia
»Third-spacing
»Hypervolemia
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Hypovolemia
Hypovolemia
• Who’s at risk?
– Lethargic
– Depressed
– Vomiting
– Dementia
– Fever
– Difficulty swallowing
– Diarrhea
– Certain drugs
– Trauma: blood loss
Hypovolemia: Dehydration
• Defined: the volume of body
fluid is lower in all compartments:
intra- and extracellular, electrolytes
and other chemical substances in the
fluid.
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Pathophysiology & Etiology
• Fluid loss in excess of fluid intake
• Decrease circulatory volume:
– Increase heart rate
– BP lowers
– Increase respiratory
– Increase temp
S & S: HYPOVOLEMIA
• Earliest: thirst
• VS changes
• Decrease in urine
• Mental status: sleepy
• Dry mouth
• Poor skin turgor
Medical Management: Hypovolemia
• You can replace fluid…
• through IV’s, oral intake,
• blood, etc….
• You have to find the
• underlying cause to
• effectively treat and
• stop Hypovolemia
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Nursing Management: Hypovolemia
• Assess
• Make a plan
• Evaluate the outcomes
• Teach, Teach, Teach
Hypervolemia
Pathophysiology & Etiology
• Fluid intake greater than fluid loss
•Excessive oral intake
•Rapid IV infusion
•Heart failure
•Kidney disease
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Hypervolemia
• Pitting edema: indentation in
the skin after compression. Usually
not seen until 3L excess in volume.
S & S: Hypervolemia
• Weight gain
• Elevated BP
• Increased breathing effort
• Edema
• Marks on the skin from socks, rings, etc.
• Congestion in the lungs
Medical Management
• Find underlying cause of excess
fluid
• Restrict fluid
intake
• Diuretics
• Limit salt/sodium
• intake
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Nursing Management
•Assess
•Make a plan
•Evaluate the outcomes
•Teach, Teach, Teach
Third Spacing
• Defined: Fluid leaves
• its normal areas and moves out into the tissue
– Low level of
– albumin
– Severe burns
– Severe allergic
– reactions
S & S: Third Spacing
• S & S hypovolemia without the
weight loss.
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Medical Management
• Restore circulatory volume
• Albumin: helps restore osmotic pressure:
which then allows trapped fluid to be
pulled back into intravascular space.
• Most physicians will order a diuretic with
albumin to stop hypervolemia when the
fluid is back where it should be.
Nursing Management
•Assess
•Make a plan
•Evaluate the outcomes
•Teach, Teach, Teach
Electrolyte Imbalances
• Sodium
• Potassium
• Calcium
• Magnesium
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Sodium Imbalances
• Normal levels 135-145mEq/L
• Found in extracellular fluid
• Maintains nerve and muscle
activity
• Regulates and distributes fluid
throughout the body
HYPONATREMIA
• Loss of sodium
– Diaphoresis
– Excessive water drinking
– Non-electrolyte IV fluid
– Diuresis
– Vomiting/GI suctioning
– Addison’s Disease
HYPONATREMIA
• S & S:
– Confusion
– Weakness
– Tachycardia
– Temperature
– Anorexia
– N/V
Severe S & S:
convulsions/coma
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HYPERNATREMIA
• Excessive amount of sodium
in the blood
• Watery diarrhea
• More salt than water intake
• High fever
• Severe burns
• Decrease water intake
HYPERNATREMIA
• S & S:
– Thirst
– Dry mucous
membranes
– Low output
– Fever
– Dry tongue
– Lethargy
POTASSIUM IMBALANCES
• Main electrolyte (CATION)
found in intracellular fluid
• Potassium works similar to
sodium, except inside the cells
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HYPOKALEMIA
• Loss of potassium (K+)
– Diuretics
– N/V/D
– Corticosteroids
– IV insulin/glucose
– IV nutrition (if K+ not added in)
HYPOKALEMIA
• S & S– Fatigue/weakness
– Leg cramps
– Dysrhythmias
– N/V
Severe S & S
hypotension, cardiac or respiratory arrest, death
HYPOKALEMIA
• Treatment:
– Mild: K+ rich foods or oral K+
– Severe: IV K+ administration
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HYPERKALEMIA
• Excess in potassium levels
• Renal failure
• Severe burns
• Overuse of K+
• Crushing injuries
HYPERKALEMIA
• S & S:
– N/V/D
– Weakness
– Cardiac dysrhythmias
HYPERKALEMIA
• Treatment:
– Mild:
• avoidance of K+ rich foods
– Severe:
• IV insulin/glucose combo
• Kayexalate
• Dialysis
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CALCIUM IMBALANCES
• Most calcium is found in bone
and teeth
• Only about 1% in blood: needed
for blood clotting
cardiac muscle
nerve impulses
HYPOCALCEMIA
• Low calcium level
– Vit D deficiency
– Thyroid disease
– Severe burns
– Pancreatitis
– Medications
– Abdominal problems
– Rapid administration of blood
HYPOCALCEMIA
• S & S:
– Tingling to extremities
– Tingling to the mouth area
– Muscle/abd. Cramping
– Muscle twitching
Severe:
laryngeal spasm, bleeding, dysrhythmias
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HYPOCALCEMIA
• Treatment:
–Mild:
• Oral calcium
• Vitamin D
–Severe:
• IV Calcium
HYPERCALCEMIA
• Excess calcium
–Parathyroid gland tumors
–Multiple fractures
–Paget’s Disease
–Immobilization
–Chemo/CA
HYPERCALCEMIA
• S & S:
–Deep bone pain
–Constipation
–N/V
–Fractures
–Mental changes
–Kidney stones
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HYPERCALCEMIA
• Treatment:
– Mild:
• Increase fluid intake
• Limiting calcium consumption
– Severe:
• IV NS
• Diuretics
• Meds. that help regulate calcium levels
• If CA present, treated on individual basis
MAGNESIUM IMBALANCES
• Found in bone, heart, liver, and
skeletal muscle cells
• Nerve impulses
• Muscle excitability
• Helps with Vit B
functioning
HYPOMAGNESEMIA
• Loss of magnesium
–ETOH abuse
–Diabetic ketoacidosis
–Kidney disease
–Severe burns
–Malnutrition
–Gastric problems
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HYPOMAGNESEMIA
• S & S:
– Tachycardia
– Dysrhythmias
– Neuro. Irritability
– Leg cramps
– Hypertension
– Dysphagia
– Seizures
HYPOMAGNESEMIA
• Treatment:
– Mild:
• Food rich in magnesium
• Oral supplement of magnesium
– Severe:
• IV magnesium sulfate
HYPERMAGNESEMIA
• Excess of magnesium
– Renal failure
– Addison’s disease
– Antacids/laxatives
– Thyroid disease
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HYPERMAGNESEMIA
• S & S:
–Flushing
–Hypotension
–Lethargy
–Bradycardia
–Depressed respirations
–coma
HYPERMAGNESEMIA
• Treatment:
–Mild:
•Stop oral administration
–Severe:
•Hemodialysis
•Mechanical ventilation
ACID-BASE BALANCE
• Acids and bases are also found in
body fluid
– Example ACID: H2CO3 Carbonic acid
– Example BASE: HCO3 Bicarbonate
Acid/base influences the pH of body fluid
Normal pH: 7.35-7.45
Below 7.35: acidosis
Above 7.45 alkalosis
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ACID-BASE BALANCE
• The pH is regulated by:
– Chemical Regulation
• Buffer systems: adding hydrogen causes
acididty…taking away hydrogen ions causes
alkalinity.
– Oxygen Regulation
• Lungs regulate the amount of CO2 stored to
regulate pH (CO2 part of carbonic acid)
• Kidneys regulate the amount of bicarb.
excreted or stored in the body (alkaline)
ACID-BASE IMBALANCES
• Life-threatening
• Death occurs quickly if less than
6.8 (acidic) or greater than 8.0
(alkalotic)
• ABG’s measure pH and acid/base
components found in the blood
ACID-BASE IMBALANCES
• Types of imbalances:
–Acidosis
• Metabolic
• Respiratory
–Alkalosis
• Metabolic
• Respiratory
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METABOLIC ACIDOSIS
• Define: decrease in pH
because of an increase in acids
other than carbonic acid
• Decrease in oxygen to cells that
result in anearobic metabolism:
producing lactic acid.
METABOLIC ACIDOSIS
• S & S:
– Deep, rapid breathing (Kussmaul’s)
– Anorexia
– N/V
– Weakness
– Confusion
– Cardiac problems
– Coma and death
METABOLIC ACIDOSIS
• Diagnosis:
–↓pH initially
–↓HCO3
–Normal PaCO2
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METABOLIC ACIDOSIS
• The initial response from the body is to try to change the balance to compensate for the imbalance
• Partial compensation: deep breathing will burn off CO2 and ↓ to try to normalize the pH…
– pH is still ↓
– HCO3 is ↓
– Now the PaCO2 is ↓
METABOLIC ACIDOSIS
• The body will continue this trend until the pH returns to normal
• This is considered full compensation
– pH normal
– HCO3 ↓
– PaCO2 ↓
If the body is healthy enough, it can maintain this for a long period…until the problem is found and corrected…if not corrected…the body will begin to decompensate and the problem returns
METABOLIC ALKALOSIS
• Defined: increase in pH because
of additional bicarb. or decrease
in hydrogen
• Overuse of alkalitic drugs
• Diuretic therapy
• Vomiting
• Hypokalemia
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METABOLIC ALKALOSIS
• S & S
– Anorexia
– N/V
– Circumoral paresthesias
– Confusion
– Spasm and reflex problems
– ↓ resp. rate
METABOLIC ALKALOSIS
• Initial:
– ↑ pH
– ↑ HCO3
– Normal PaCO2
– Again, the respiratory regulator kicks in and tries to normalize the pH by using slower and more shallow breathing to retain CO2 compensation begins.
METABOLIC ALKALOSIS
• Partial Compensation:
– ↑ pH
– ↑ HCO3
– ↑ PaCO2
• Compensation:
– ↑ pH (but usually lower)
– ↑ HCO3 (lower)
– ↑ Pa CO2
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RESPIRATORY ACIDOSIS
• Defined: excess in carbonic acid which
decreases the pH
• Resp. problems cause this:
– Pneumothorax/hemothorax
– Pulmonary edema
– COPD
Things that cause the lungs to retain
carbon dioxide CO2
RESPIRATORY ACIDOSIS
• Initial:
– ↓ pH
– Normal HCO3
– ↑ PaCO2
This time the kidneys go to work…they try
to absorb more of the HCO3 in an
attempt to balance out the increase in
PaCO2…this can take 2-3 days.
RESPIRATORY ACIDOSIS
• Partial compensation:
– ↓ pH
– ↑ HCO3
– ↑ PaCO2
• Compensation:
– Normal pH
– ↑ HCO3
– ↑ PaCO2
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RESPIRATORY ACIDOSIS
• Treatment:
– Have to find underlying cause and
treat
– May need to mechanically ventilate
– May need to add IV sodium bicarb
– Need to maintain airway and keep
secretions to a minimum
RESPIRATORY ALKALOSIS
• Define: Rapid breathing causes an
increased release of carbonic acid
with expiration (Hyperventilating)
– Anxiety
– High fever over long period
– Thyroid problems
– Aspirin poisoning
– ventilators
RESPIRATORY ALKALOSIS
• S & S
–Increased resp. rate
–Feeling faint
–Tingling
–Sweating
–Dry mouth
–Severe: convulsions
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RESPIRATORY ALKALOSIS
• Initial:
– ↑ pH (High normal)
– Normal HCO3
– ↓ PaCO2
– Again, the kidneys kick in and try to
normalize the balance by excreting HCO3
and trying to balance the pH
RESPIRATORY ALKALOSIS
• Partial compensation:
– Normal high pH
– ↓ HCO3
– ↓ PaCO2
• Compensation:
– Normal pH
– ↓ HCO3
– ↓ PaCO2