Transcript Power Notes

Chapter 34
Fluid, Electrolyte, and
Acid-Base Balance
Physiology of Fluid and AcidBase Balance
 The body normally maintains a balance
between the amount of fluid taken in and
the amount excreted.
 Homeostasis is the maintenance of this
balance in response to changes in the
internal and external environments.
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Physiology of Fluid and AcidBase Balance
 Fluid Compartments
• Cells
• Blood vessels
• Tissue space (interstitial space)
- Space between the cells and blood vessels
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Fluid Compartments
 Two Types of Body Fluids
• Intracellular fluid (ICF) is fluid within the cell.
• Extracellar fluid (ECF)
- Intravascular fluid (within blood vessels)
- Interstitial fluid (between cells; fluid that
surrounds cells)
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Fluid Compartments
 Solute: Substance dissolved in a
solution.
 Solvent: Liquid that contains a substance
in solution.
 Permeability: Capability of a substance,
molecule, or ion to move across a
membrane.
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Fluid Compartments
 Cells have semi-permeable membranes
that allow fluid and solutes to pass into
and out of the cell.
 Blood vessels have semi-permeable
membranes that bathe and feed the cells.
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Body Water Distribution
 Water represents 45% to 75% of the
body’s total weight.
 About two-thirds of the body fluid is
intracellular.
 One-third of body fluid is extracellular.
• One-fourth of this fluid is intravascular.
• Three-fourths is interstitial fluid.
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Body Water Distribution
 Bones are made up of nearly one-third
water.
 Muscles and brain cells contain 70%
water.
 Body fat is essentially water-free.
 The ratio of water to body weight is
greater in leaner people than in obese
people.
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Functions of Body Water
 Water acts as a solvent for essential
nutrients.
 Water transports nutrients and oxygen
from the blood to the cells.
 Water removes waste material and other
substances from the cells and returns it
to the blood for excretion by the body.
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Functions of Body Water
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Gives shape and form to cells.
Regulates body temperature.
Acts as a lubricant in joints.
Cushions body organs.
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Electrolytes
 Compounds that, when dissolved in
water or another solvent, form or
dissociate into ions
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Sodium (Na+)
Potassium (K+)
Calcium (Ca2+)
Magnesium (Mg2+)
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Electrolytes
 Promote normal neuromuscular
excitability.
 Maintain body fluid osmolarity.
 Regulate acid base balance.
 Distribute body fluids between fluid
compartments.
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Electrolytes
 Extracellular fluid contains the largest
quantities of sodium, chloride, and
bicarbonate ions, and small quantities of
potassium and calcium.
 Intracellular fluid contains only small
quantities of sodium and chloride, almost
no calcium ions, and large quantities of
potassium.
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Movement of Body Fluids
 Physiological forces affect the transport
of molecules of water, foods, gases,
wastes, and ions.
 Maintain a balance between extracellular
and intracellular fluid compartments.
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Movement of Body Fluids
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Diffusion
Osmosis
Active Transport
Hydrostatic Pressure
Filtration
Colloid Osmotic Pressure
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Regulators of Fluid Balance
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Fluid and Food Intake and Loss
Skin
Lungs
Gastrointestinal Tract
Kidneys
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Acid-Base Balance
 Acid-base balance refers to the
homeostasis of the hydrogen ion
concentration in extracellular fluid.
 An acid is a substance that donates
hydrogen ions.
 A base is a substance that accepts
hydrogen ions.
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Acid-Base Balance
 The pH symbol indicates the hydrogen
ion concentration of body fluids.
 7.35 to 7.45 is the normal pH range of
extracellular fluid.
 Acidity increases as the pH decreases.
 Alkalinity decreases as the pH increases.
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Regulators of Acid-Base
Balance
 Buffer Systems
• Two or more chemical compounds that
prevent marked changes in hydrogen ion
concentration when either an acid or a base
is added to a solution
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Regulators of Acid-Base
Balance
 Respiratory Regulation of Carbon
Dioxide in Extracellular Fluid
• Increased carbon dioxide levels in
extracellular fluid increase rate and depth of
respirations so that more carbon dioxide is
exhaled.
• Decreased carbon dioxide levels depress
respirations to maintain carbon dioxide.
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Regulators of Acid-Base
Balance
 Renal Control of Hydrogen Ion
Concentration
• The kidneys control extracellular fluid pH by
removing hydrogen or bicarbonate ions from
body fluids.
- When the kidneys excrete more bicarbonate
ions, the urine becomes more alkaline.
- When the kidneys excrete more hydrogen ions,
the urine becomes more acidic.
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Factors Affecting Fluid and
Electrolyte Balance
 Age
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Adult, 60% water
Child, 60% to 77% water
Infant, 77% water
Embryo, 97% water
 In the elderly, body water diminishes
because of tissue loss.
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Factors Affecting Fluid and
Electrolyte Balance
 Lifestyle
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Stress
Exercise
Warm or humid environment
Diet
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Disturbances in Electrolyte and
Acid-Base Balance
 In illness, one or more of the homeostatic
regulating mechanisms may be affected,
or the imbalance may become too great
for the body to correct without treatment.
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Electrolyte Disturbances
 Sodium is the primary determinant of
extracellular fluid concentration.
 Alterations in sodium concentration can
produce profound effects on the central
nervous system and circulating blood
volume.
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Electrolyte Disturbances
 Hyponatremia is a deficit in the
extracellular level of sodium.
 The ratio of water to sodium is too high (a
hypo-osmolar state).
 Water moves out of the vascular space
into the interstitial space, causing edema.
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Electrolyte Disturbances
 Hypernatremia is an excess of sodium in
the extracellular fluid.
 The ratio of sodium to water is too high
(hyperosmolar state).
 Extracellular osmotic pressure pulls fluid
out of the cells into the extracellular
space, causing edema.
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Electrolyte Disturbances
 Potassium
• The normal range of extracellular potassium
is narrow (3.5-5.0 mEq/L).
• Small deviations cause serious or lifethreatening effects on physiologic functions.
• A reciprocal relationship exists between
sodium and potassium.
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Electrolyte Disturbances
 Hypokalemia is a decrease in the
extracellular level of potassium.
 Gastrointestinal disturbances and the use
of potassium wasting diuretics, laxatives,
corticosteroids, and antibiotics place the
client at risk for hypokalemia.
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Electrolyte Disturbances
 Hyperkalemia is an increase in the
extracellular level of potassium.
 Three major drug groups may cause
hyperkalemia.
• Potassium-sparing diuretics
• Central nervous system agents
• Oral and intravenous replacement
potassium salts
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Electrolyte Disturbances
 Calcium
• Essential for normal bone and teeth
formation
• Critical factor in normal blood clotting
• Maintenance of normal nerve and muscle
excitability
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Electrolyte Disturbances
 Hypocalcemia is a decrease in the
extracellular level of calcium.
 Hypercalcemia is an increase in the
extracellular level of calcium.
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Electrolyte Disturbances
 Magnesium
• Coenzyme in the metabolism of
carbohydrates and proteins
• Mediator in neuromuscular activity
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Electrolyte Disturbances
 Hypomagnesemia is a decrease in the
extracellular level of magnesium and
usually occurs with hypokalemia and
hypocalcemia.
 Hypermagnesemia refers to an increase
in the extracellular level of magnesium.
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Electrolyte Disturbances
 Phosphate
• Main intracellular anion
• Appears as phosphorus in the serum.
• Similar to calcium in that Vitamin D is
needed for its reabsorption from the renal
tubules.
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Electrolyte Disturbances
 Hypophosphatemia is a decreased
extracellular level of phosphorus.
 Hyperphosphatemia is an increased
extracellular level of phosphorus.
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Electrolyte Disturbances
 Chloride and water move in the same
direction as sodium ions.
 A loss of chloride can be compensated
for by an increase in bicarbonate.
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Electrolyte Disturbances
 Hypochloremia is a decrease in the
extracellular level of chloride.
• Gastrointestinal tract losses because of the
acid content of gastric juices (hydrogen
chloride), placing the client at risk for
metabolic alkalosis
 Hyperchloremia usually occurs with
dehydration, hypernatremia, and
metabolic acidosis.
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Acid-Base Disturbances
 Laboratory Data
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Arterial blood gases
Blood pH
Bicarbonate ion concentration
Sodium, potassium, chloride levels
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Acid-Base Disturbances
 Respiratory Acidosis (Carbonic Acid
Excess)
 Respiratory Alkalosis (Carbonic Acid
Deficit)
 Metabolic Acidosis (Bicarbonate Deficit)
 Metabolic Alkalosis (Bicarbonate Excess)
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Assessment
 Health History
• Clients receiving certain treatments, such as
medications and IV therapy
• Data specific to fluids
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Assessment
 Physical Examination
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Daily weight
Vital signs
Intake and output
Edema
Skin turgor
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Assessment
 Physical Examination
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Buccal (oral) cavity
Eyes
Jugular and hand veins
Neuromuscular system
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Assessment
 Diagnostic and Laboratory Data
• Hemoglobin and hematocrit indices
- With severe dehydration and hypovolemic shock,
the hematocrit is increased.
- Overhydration reduces the hematocrit by dilution.
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Laboratory Data
 Osmolality
• Measurement of the total concentration of
dissolved particles (solutes) per kilogram of
water
- Serum osmolality
- Urine osmolality
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Assessment
 Diagnostic and Laboratory Data
• Urine pH
• Serum albumin
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Nursing Diagnosis
 Excess Fluid Volume
 Deficient Fluid Volume
 Risk for Deficient Fluid Volume
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Other Nursing Diagnoses
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Impaired Gas Exchange
Decreased Cardiac Output
Risk for Infection
Impaired Oral Mucous Membrane
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Deficient Knowledge
 Dehydration is one of the most common
and most serious fluid balances.
 Information obtained from a client’s
health history may indicate the client’s
level of understanding and perception of
alterations in fluid, electrolyte and acidbase balance.
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Planning and Outcome
Identification
 Expected outcomes for clients with fluid
imbalances include outcomes relative to
interventions.
 Achievement of the goals and the client’s
expected outcomes indicates resolution
of the problem.
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Implementation
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Monitor Daily Weight
Measure Vital Signs
Measure Intake and Output
Provide Oral Hygiene
Initiate Oral Fluid Therapy
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Implementation
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Nothing by Mouth
Restricted Fluids
Forced Fluids
Maintain Tube Feedings
Monitor Intravenous Therapy
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Implementation
 Monitor Intravenous Therapy
• Administration of fluids, electrolytes,
nutrients, or medications by the venous
route when fluid losses are severe or the
client cannot tolerate oral or tube feedings
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Intravenous Therapy
 Parenteral Fluids
• Hypotonic
• Isotonic
• Hypertonic
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Intravenous Therapy
 Equipment
• Administration Set
• Health Hazard
• Intravenous Filters
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Intravenous Therapy
 Equipment
• Needles and venous peripheral-short
catheters
- Butterfly needles
- Intracath
- Angiocatheter
• Peripheral intravenous (PI)
• Heparin locks (intermittent venous locks)
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Intravenous Therapy
 Equipment
• Needle-Free System
• Vascular Access Devices (VAD)
- Various catheters, cannulas, infusion ports that
allow for long-term IV therapy or repeated access
to the central venous system
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Intravenous Therapy
 Preparing an Intravenous Solution
• Initiating IV therapy
• Vein finder
 Administering IV Therapy
• Flushing
• Regulating IV solution flow rates
• Calculation of flow rates
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Intravenous Therapy
 Flow Control Devices
• Manual flow-control devices
• Electronic infusion devices
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Intravenous Therapy
 Managing IV Therapy
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Hypervolemia
Infiltration
Phlebitis
Intravenous dressing change
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Intravenous Therapy
 Discontinuation of Intravenous Therapy
 Blood Transfusion
• Whole blood and blood products
• Initial assessment and preparation
• Administering whole blood or a blood
component
• Safety measures
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Complementary Therapy
 Herbs and certain foods
 Naturopathic health care practitioners
 Considerations for using complementary
therapies with traditional medications
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Evaluation
 The nurse should focus on the client’s
responses when evaluating whether time
frames and expected outcomes are
realistic.
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