Transcript Chain of Survival and EMSC

Chapter 25
Fluid, Electrolyte, and Acid-Base
Balance
Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.
Learning Objectives
Theory
1)
Discuss the various functions water performs
in the body.
2)
List the major electrolytes and the function of
each.
3)
Describe three ways in which body fluids are
continually being distributed among the fluid
compartments.
4)
Identify the signs and symptoms of the
common fluid and electrolyte imbalances.
Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.
Slide 2
Learning Objectives
Clinical Practice
1)
Assess an assigned patient for signs of fluid
and electrolyte imbalance.
2)
From patient laboratory results, identify
electrolyte values that are abnormal.
3)
Implement teaching for the patient with
hypokalemia.
4)
Develop a plan of care for a patient who has
a fluid and electrolyte imbalance.
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Slide 3
Composition of Body Fluids

Water

The two largest constituents of the body are
water and electrolytes
 Water serves four functions:
• Is a vehicle for transporting substances to and from
cells
• Aids in heat regulation
• Assists in H+ balance in the body
• Is a medium for enzymatic action of digestion
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Slide 4
Water

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More than half of the body’s weight is water
Amount varies with age, sex, and health
status
Males: approximately 60 %
Females: approximately 50%
Infants and the elderly more easily affected
by changes in fluid balance
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Slide 5
Water (cont’d)
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
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Infants and the elderly become dehydrated
more rapidly
Infants’ kidneys reabsorb less fluid
Elderly have less antidiuretic hormone and
diminished thirst sensation
Water is critical to maintaining homeostasis
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Slide 6
Sources of Water and Avenues of Loss

Intake

Oral
 Food
 Metabolism
 Total

1500 mL
800 mL
200 mL
2500 mL
Output





Urine
Perspiration
Feces
Expired air
Total
1500 mL
400 mL
200 mL
400 mL
2500 mL
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Slide 7
Composition of Body Fluids

Electrolytes

Minerals or salts dissolved in body fluids
 In solution, they break up into ions
 Ions have electrical charges
 Cations have positive charges
 Anions have negative charges
 Each cation must be balanced by an anion
 The major source of electrolytes is diet
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Slide 8
Electrolytes

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Sodium: water regulation and balance
Potassium: nerve impulse transmission, muscle
contraction, plasma, acid-base balance
Calcium: muscle activity, blood coagulation
Magnesium: nerve impulse transmission, muscle
contraction
Phosphate: ATP production
Chloride: hydrochloric acid production, acid-base
balance
Bicarbonate: acid-base balance
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Slide 9
Major Electrolytes: Normal Range
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Electrolyte
Sodium
Potassium
Calcium
Magnesium
Phosphate
Chloride
Bicarbonate
Normal Range
135-145 mEq/L
3.5-5 mEq/L
8.4-10.6 mg/dL
1.3-2.5 mg/dL
2.5-4.5 mg/dL
96-106 mEq/L
22-26 mEq/L
Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.
Slide 10
Non-Electrolytes


Amino acids (proteins), glucose, and fatty
acids
Remain bound together when dissolved in
body fluid
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Slide 11
Non-Electrolytes: Blood


Normal circulating blood volume is 4 to 6 L
Composed of:
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Erythrocytes (red cells)
Leukocytes (white cells)
Platelets (thrombocytes)
Carried in plasma
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Slide 12
Non-Electrolytes: Blood (cont’d)



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Plasma proteins and colloids contribute to
plasma osmotic pressure, which keeps fluid
in the vascular compartment
Anything that alters body fluid volume also
alters plasma volume
Plasma volume can affect blood pressure
Plasma volume can affect circulation
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Slide 13
Distribution of Body Fluids

Body fluids are:

Intracellular (within the cell)
 Extracellular (outside the cell)
• Intravascular
• Interstitial
• Transcellular
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Slide 14
Extracellular Fluid
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Makes up approximately 1/3 of the total body
water
Transports nutrients, oxygen, and waste
products to and from cells
Is regulated by renal, metabolic, and
neurologic factors
Is high in sodium content
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Slide 15
Intravascular Fluid
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The fluid within the blood vessels
Consists of plasma and fluid within the blood
cells
Contains large amounts of protein and
electrolytes, which help maintain
intravascular volume
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Slide 16
Transcellular Fluids
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Aqueous humor (in the eyes)
Saliva
Cerebrospinal fluid
Pleural, peritoneal, synovial, and pericardial
fluids
Gastrointestinal secretions
Fluid in the urinary tract
Lymphatic system fluids
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Slide 17
Movement of Fluids and
Electrolytes



Water taken in by ingesting fluids and food and
through metabolism
Thirst mechanism in the hypothalamus
regulates thirst based on concentration of
electrolytes and solutes in circulation
Kidney the main organ of water secretion, with
some loss in feces, perspiration, and breathing.
Water retention based on aldosterone levels,
antidiuretic hormone (ADH) levels, and atrial
natriuretic peptide levels.
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Slide 18
Fluid, Electrolyte, and Nutrient
Transport Mechanisms

Diffusion—passive transport
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

Process by which substances move back and
forth across the membrane until evenly distributed
throughout the available space
Substances move from high to low concentration
until concentration on both sides of the membrane
is equal
Glucose, oxygen, carbon dioxide, water, and other
small ions and molecules move by diffusion
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Slide 19
Figure 25-2A: Diffusion
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Slide 20
Fluid, Electrolyte, and Nutrient
Transport Mechanisms

Osmosis—passive transport
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Movement of pure solvent (liquid) across a
membrane
Water moves from area of less solute
concentration to area of greater concentration until
the solutions in the compartments are of equal
concentration
Takes place via a semipermeable membrane
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Slide 21
Figure 25-2B: Osmosis
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Slide 22
Fluid, Electrolyte, and Nutrient
Transport Mechanisms
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Filtration—passive transport
Movement of water and suspended
substances outward through a
semipermeable membrane
Hydrostatic pressure


Causes fluid to press outward on the vessel
The force promotes filtration, forcing movement of
water and electrolytes through the capillary wall to
the interstitial fluid
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Slide 23
Figure 25-2D: Filtration
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Slide 24
Fluid, Electrolyte, and Nutrient
Transport Mechanisms

Active transport
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Requires cellular energy
Can move molecules into cells regardless of their
electrical charge or the concentrations already in
the cell
The energy source for the process is adenosine
triphosphate (ATP)
Can move amino acids, glucose, iron, hydrogen,
sodium, potassium, and calcium through the cell
membrane
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Slide 25
Figure 25-2C: Active transport
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Slide 26
Fluid Volume Deficit

At risk:

Patients unable to take in enough fluid
• Impaired swallowing, extreme weakness, disorientation
or coma, or unavailability of water

Patients who lose excessive amounts of fluid
• Prolonged vomiting, diarrhea, hemorrhage, diaphoresis
(sweating), or excessive wound drainage

Result is dehydration
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Slide 27
Dehydration

Dehydration


When too little water in the plasma, water drawn
out of the cells by osmosis to equalize
concentration, and the cells shrivel
Treated by fluid administration, either orally or
intravenously
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Slide 28
Signs and Symptoms of
Dehydration
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Thirst
Weakness
Dizziness
Postural hypotension
Decreased urine
production
Concentrated urine
Dry, cracked lips
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Dry mucous
membranes
Thick saliva
Dry, scaly skin
Poor tissue turgor
Flat neck veins
Increased pulse rate
Weak, thready pulse
Elevated temperature
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Slide 29
Figure 25-3: Testing for tissue turgor
and signs of dehydration
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Slide 30
Fluid Volume Excess
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Healthy people do not ordinarily drink too
much water
When people become ill they may take in
more water than they excrete
Receive intravenous fluid too quickly
Given tap-water enemas
Drink more fluids than they can eliminate
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Slide 31
Fluid Volume Excess (cont’d)
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Signs of overhydration
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Weight gain
Crackles in the lungs (wet lungs)
Slow bounding pulse
Elevated blood pressure
Possibly edema
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Slide 32
Figure 25-4: Example of pitting edema
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Slide 33
Electrolyte Imbalance: Sodium
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Hyponatremia
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Sodium deficit; can be from decreased sodium or
increased water intake and retention
May be caused by excessive vomiting or diarrhea
Hypernatremia
Sodium excess; most commonly from water
loss from fever or respiratory infection
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Slide 34
Electrolyte Imbalance: Potassium

Hypokalemia


Occurs with excess potassium or loss of body
water; may be from poor diet, vomiting, diarrhea,
excessive sweating, or diuretic therapy
Hyperkalemia

Occurs with burns, crush injuries, uncontrolled
diabetes mellitus, and renal failure
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Slide 35
Electrolyte Imbalance: Calcium

Hypocalcemia


Occurs with nutritional deficiency of calcium or
vitamin D or in bone disorders such as metastatic
cancer of the bone
Hypercalcemia

Most cases related to hyperparathyroidism or
malignancy such as multiple myeloma
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Slide 36
Electrolyte Imbalance: Calcium (cont’d)

Calcium imbalances

Hypocalcemia
• Calcium level drops below 8.4 mg/dL
• Can occur from nutritional deficiency of calcium or
vitamin D
• Occurs in disorders in which there is a shift of calcium
into the bone

Hypercalcemia
• Calcium level above 10.6 mg/dL
• Most cases are related to hyperparathyroidism or
malignancy in which there is metastasis with bone
resorption
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Slide 37
Electrolyte Imbalance: Magnesium

Hypomagnesemia
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
Results from malabsorption, malnutrition, renal
tubular dysfunction, thiazide diuretic use,
extensive gastric suction, or diarrhea
Hypermagnesemia

Occurs only in presence of renal failure
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Slide 38
Electrolyte Imbalances

Anion imbalances
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Hypochloremia
• Chloride level below 96 mEq/L is associated with
hyponatremia

Hyperchloremia
• Chloride level above 106 mEq/L
• Occurs along with hypernatremia and a form of metabolic
acidosis
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Slide 39
Electrolyte Imbalances (cont’d)

Anion imbalances

Hypophosphatemia
• Occurs when the level of phosphate falls below 3.0
mg/dL
• May result from use of aluminum-containing antacids,
from vitamin D deficiency, or from hyperparathyroidism

Hyperphosphatemia
• A phosphate level above 4.5 mg/dL
• Commonly occurs in renal failure
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Slide 40
Acid-Base Balance
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
Important in maintaining homeostasis
pH: measure of the degree of acidity or alkalinity
Normal serum pH is 7.35 to 7.45
Death may occur if pH is less than 6.8 or greater
than 7.8
Balance between bicarbonate and carbonic acid


Carbonic acid retained or removed by respiratory
system
Bicarbonate retained or removed by kidneys
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Slide 41
Acid-Base Balance (cont’d)

Bicarbonate



Normal range is 22 to 26 mEq/L
Acts as buffer to neutralize excess acids in the
body and maintain bicarbonate-to-carbonic acid
ratio at 20:1
Kidneys selectively reabsorb or excrete
bicarbonate to regulate serum levels and help
maintain acid-base balance
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Slide 42
Acid-Base Balance (cont’d)

Control mechanisms



Blood buffer system
• Consists of weak acids and weak bases
Lungs
• Carbon dioxide and water are expired from the lungs
Urinary system
• Enzymes promote the dissociation of carbonic acid to
free hydrogen ions
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Slide 43
Acid-Base Balance:
Respiratory Acidosis

Increased carbon dioxide levels from:

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Airway obstruction
Pneumonia, asthma
Chest injuries
Opiate intake
Chronic obstructive lung disease
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Slide 44
Acid-Base Balance:
Metabolic Acidosis

An excessive loss of bicarbonate ions or
retention of hydrogen ions caused by:




Kidney disease
Diabetic ketoacidosis
Circulatory failure
Shock states
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Slide 45
Acid-Base Balance:
Respiratory Alkalosis

Usually caused by:

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
Anxiety
High fever
Hyperventilation
Salicylate poisoning (ASA overdose)
Encephalitis
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Slide 46
Acid-Base Balance:
Metabolic Alkalosis

Caused by:





Vomiting
Gastric suctioning
Excessive antacid consumption
Diuretic therapy
Potassium deficit
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Slide 47