Fluid, Electrolyte, and Acid-Base Balance

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Fluid, Electrolyte, and Acid-Base Balance
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Learning Outcomes

• Discuss the function, distribution, movement, and
  regulation of fluids and electrolytes in the
  body.
• Describe the regulation of acidbase balance in
  the body, including the roles of the lungs, the
  kidneys and buffers.
• Identify factors affecting normal body fluid,
  electrolyte, and acidbase balance.
• Discuss the risk factors for and the causes and
  effects of fluid, electrolyte, and acidbase
  imbalances.
• Collect assessment data related to the clients
  fluid, electrolyte, and acidbase balances.

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Learning Outcomes

• Identify examples of nursing diagnoses, outcomes,
  and interventions for clients with altered
  fluid, electrolyte, or acidbase balance.
• Teach clients measures to maintain fluid and
  electrolyte balance.
• Implement measures to correct imbalances of
  fluids and electrolytes or acids and bases such
  as enteral or parenteral replacements and blood
  transfusions.
• Evaluate the effect of nursing and collaborative
  interventions on the clients fluid, electrolyte,
  or acidbase balance.

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• A delicate (fragile) balance of fluids,
  electrolytes, and acids and bases is maintained
  in the body. This balance depends on multiple
  physiologic processes that regulate fluid intake
  and output and the movement of water and
  substances dissolved in it between body
  compartments.

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• Water is vital to health and normal cellular
  function. It serves as a medium for metabolic
  reactions within the cells a transporter for
  nutrients, waste products, and other substances
  a lubricant an insulator a shock absorber and
  one means of regulating and maintaining body
  temperature.

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• The bodys fluid is divided into two major
  compartments intracellular and extracellular.
  Intracellular fluid (ICF) is found within the
  cells, and extracellular fluid (ECF) is found
  outside the cells.

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• The two main compartments of the ECF are
  intravascular fluid (plasma) and interstitial
  fluid (surrounds the cells). Other compartments
  of ECF include lymph and transcellular fluids
  such as cerebrospinal, pericardial, pancreatic,
  pleural, intraocular, biliary, peritoneal, and
  synovial fluids. Intracellular fluid is vital to
  normal cell functioning.

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• It contains solutes such as oxygen, electrolytes,
  and glucose, and it provides a medium in which
  metabolic processes of the cell take place.
  Extracellular fluid is the transport system that
  carries nutrients to and waste products from the
  cells.

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• Fluids and electrolytes move among the body
  compartments by osmosis, diffusion, filtration,
  and active transport. The volume and composition
  of body fluids is regulated through several
  homeostatic mechanisms the kidneys, the
  endocrine system, the cardiovascular system, the
  lungs, and the gastrointestinal system.

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• The antidiuretic hormone (ADH), also called
  arginine vasopressin (AVP), the
  renin-angiotensin-aldosterone system.

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Movement of Body Fluids

• Osmosis
• Diffusion
• Filtration
• Active transport

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Osmosis Water molecules move from the less
concentrated area to the more concentrated area
in an attempt to equalize the concentration of
solutions on two sides of a membrane.
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Diffusion The movement of molecules through a
semipermeable membrane from an area of higher
concentration to an area of lower concentration.
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Schematic of filtration pressure changes
within a capillary bed. On the arterial side,
arterial blood pressure exceeds colloid osmotic
pressure, so that water and dissolved substances
move out of the capillary into the interstitial
space. On the venous side, venous blood pressure
is less than colloid osmotic pressure, so that
the water and dissolved substances move into the
capillary.
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Regulating Body Fluids

• Fluid intake
• Thirst
• Fluid output
• Urine
• Insensible loss
• Feces

• Maintaining homeostasis
• Kidneys
• ADH
• Renin-angiotensin-aldosterone system

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• ECF and ICF contain ions (charged particles).
  Anions are negative ions and cations are positive
  ions called electrolytes. The number of cations
  and anions in should be equal.

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• The principal electrolytes in the ECF are sodium,
  chloride, and bicarbonate. Other electrolytes
  such as potassium, calcium, and magnesium but in
  much smaller quantities.

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• Plasma and interstitial fluids (major components
  of ECF) contain essentially the same electrolytes
  and solutes with the exception of proteins, which
  are plentiful in the plasma.

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• The primary electrolytes in the ICF are
  potassium, magnesium, phosphate, and sulfate. As
  in ECF, other electrolytes are present within the
  cells, but in smaller concentrations.

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Distribution of Body Fluids
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Regulating Electrolytes

• Sodium
• Potassium
• Calcium
• Magnesium
• Chloride
• Phosphate
• Bicarbonate

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Regulation Acid-Base Balance
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• An important part of regulating the chemical
  balance or homeostasis of body fluids is
  regulating their acidity or alkalinity, which is
  measured as pH. The pH reflects the hydrogen
  concentration of the solution.

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• The higher the hydrogen ion concentration, the
  lower the pH (more acidic) and vice versa. Body
  fluids are maintained within a narrow range that
  is slightly alkaline (arterial blood is between
  7.35 and 7.45).

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• Several body systems, including buffers, the
  respiratory system, and the renal system, are
  actively involved in maintaining the narrow pH
  range necessary for optimal function. The lungs
  and kidneys help maintain a normal pH by either
  excreting or retaining acids and bases.

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• Buffers (substance that keeps a constant balance
  between acid and alkali) prevent excessive
  changes in the pH by removing or releasing
  hydrogen ions. The major buffer system in ECF is
  the bicarbonate (HCO3) and carbonic acid (H2CO3)
  system.

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• The amounts of bicarbonate and carbonic acid in
  the body vary. However, as long as a ratio of 20
  parts of bicarbonate to 1 part of carbonic acid
  is maintained, pH remains within normal limits.
  In addition, plasma proteins, hemoglobin, and
  phosphates function as buffers.

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Regulation of Acid-BaseBalance

• Low pH acidic
• High pH alkalinic
• Body fluids maintained between pH of 7.35 and
  7.45 by
• Buffers
• Respiratory system
• Renal system

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Buffers

• Prevent excessive changes in pH
• Major buffer in ECF is HCO3 and H2CO3
• Other buffers include
• Plasma proteins
• Hemoglobin
• Phosphates

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• The lungs help regulate acidbase balance by
  eliminating or retaining carbon dioxide, a
  potential acid. Combined with water, carbon
  dioxide forms carbonic acid. This chemical
  reaction is reversible.

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• Working together with the bicarbonatecarbonic
  acid buffer system, the lungs regulate acidbase
  balance and pH by altering the rate and depth of
  respirations.

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• Carbon dioxide is a powerful stimulator of the
  respiratory center. When blood levels of carbonic
  acid and carbon dioxide rise, the respiratory
  center is stimulated and the rate and depth of
  respiration increase. Carbon dioxide is exhaled
  and carbonic acid levels fall.

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• By contrast when bicarbonate levels are
  excessive, the rate and depth of respirations are
  reduced, causing carbon dioxide to be retained,
  carbonic acid to rise, and excess bicarbonate to
  be neutralized.

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• The respiratory system response to changes in pH
  is rapid, occurring within minutes.

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• The kidneys are the ultimate long-term regulator
  of acidbase balance. They are slower to respond
  to changes, requiring hours to days to correct
  imbalances, but their response is more permanent
  and selective than that of the other systems.

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• Kidneys maintain acidbase balance by selectively
  excreting or conserving bicarbonate and hydrogen
  ions. When excess hydrogen ion is present and the
  pH falls (acidosis), the kidneys reabsorb and
  regenerate bicarbonate and excrete hydrogen ions

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• In the case of alkalosis and a high pH, excess
  bicarbonate is excreted and a hydrogen ion is
  retained.

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Factors Affecting Body Fluid, Electrolyte, and
Acid-Base Balance

• Age
• Gender
• Body size
• Environmental temperature
• Lifestyle

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• Ageinfants and growing children have much
  greater fluid turnover than adults because of
  their higher metabolic rates, increase fluid
  loss, immature kidneys (infants), rapid
  respiratory rate (infants), and greater body
  surface area (infants).

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• In elderly people normal aging process and the
  likelihood of the presence of chronic diseases
  may affect fluid balance. Thirst is blunted (not
  sharp) nephrons are less able to conserve water
  in response to ADH.

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• Gender and body sizefat cells contain little
  water and lean tissue has an increased water
  content. People with a greater percentage of body
  fat have less body fluid. Women have
  proportionally greater body fat than men and have
  less body water than men.

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• Environmental temperatureindividuals with
  illness and participation in strenuous exercise
  are at risk for fluid and electrolyte imbalances
  when the environmental temperature in high the
  loss of water and salt in sweat.

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• Lifestylediet (intake of fluid and
  electrolytes), exercise (calcium balance), and
  stress (increases cellular metabolism, blood
  glucose concentration, and cathecholamine levels)
  affect fluid and electrolyte and acidbase
  balance. Heavy alcohol consumption decreases
  calcium, magnesium, and phosphate levels and
  increases the risk of acidosis from breakdown of
  fat.

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Risk Factors for Fluid, Electrolyte, and
Acid-Base Imbalances

• Chronic diseases
• Acute conditions
• Medications
• Treatments
• Extremes of age
• Inability to access food and fluids

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• Chronic diseases (e.g., lung disease, heart
  failure, Cushings or Addisons diseases,
  diabetes mellitus, and cancer), acute conditions
  (e.g., acute gastroenteritis, burns, crushing
  injuries, surgery, or fever), medications (e.g.,
  diuretics, corticosteroids, and NSAIDs),
  treatments (e.g., chemotherapy, intravenous
  therapy or total peripheral nutrition,
  nasogastric suction, enteral feedings, mechanical
  ventilation) and other factors (such as the very
  young and the very old, inability to access food
  and fluids independently) .

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• Fluid imbalances are of two basic types isotonic
  and osmolar. Isotonic imbalances occur when water
  and electrolytes are lost or gained in equal
  proportions so that the osmolality of body fluids
  remains constant. Osmolar imbalances involve the
  loss of only water so that the osmolality of the
  serum is altered.

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Fluid Imbalances

• Isotonic loss of water and electrolytes (fluid
  volume deficit)
• Isotonic gain of water and electrolytes (fluid
  volume excess)
• Hyperosmolar loss of only water (dehydration)
• Hypo-osmolar gain of only water (overhydration)

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• Fluid imbalances are of two basic types isotonic
  and osmolar.
• Isotonic imbalances occur when water and
  electrolytes are lost or gained in equal
  proportions so that the osmolality of body fluids
  remains constant.

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• Osmolar imbalances involve the loss of only water
  so that the osmolality of the serum is altered.
  Thus there are four categories of fluid
  imbalances an isotonic loss of water and
  electrolytes (fluid volume deficit), an isotonic
  gain of water and electrolytes (fluid volume
  excess), a hyperosmolar loss of only water
  (dehydration), and a hypo-osmolar gain of only
  water (overhydration).

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• The risk for dehydration increases with older age
  due to decreased thirst sensation. Also at risk
  for dehydration are clients who are
  hyperventilating or have prolonged fever or are
  in diabetic ketoacidosis and those receiving
  enteral feedings with insufficient water.

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• Common manifestations of dehydration include
  weight loss, decreased skin turgor and capillary
  refill, dry mucous membranes, weak, rapid pulse,
  decreased blood pressure and orthostatic
  hypotension, increased specific gravity of the
  urine, hematocrit and blood urea nitrogen.

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• Overhydration may occur if only water is replaced
  or from the syndrome of inappropriate
  antidiuretic hormone (SIADH), which can result
  from some malignant tumors, AIDS, head injury, or
  administration of certain drugs such as
  barbiturates or anesthetics.

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• Common manifestations of overhydration include
  weight gain, full bounding pulse, tachycardia,
  elevated blood pressure, distended neck and
  peripheral veins, adventitious lung sounds,
  shortness of breath, and confusion.

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• Collecting Assessment Data
• Nursing history
• Physical assessment
• Clinical measurement
• Review of laboratory test results
• Evaluation of edema

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• The nursing history includes current and past
  medical history, medications, and functional,
  developmental, and socioeconomic factors. Common
  risk factors for fluid and electrolyte imbalances

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• The nurse also needs to elicit data about the
  clients food and fluid intake, fluid output, and
  the presence of signs or symptoms suggestive of
  altered fluid and electrolyte balance. The
  Assessment Interview provides examples of
  questions to elicit information regarding fluid,
  electrolyte, and acidbase balance.

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• lists the focused physical assessment of fluid,
  electrolyte, or acidbase imbalances, including
  assessment of the skin, mucous membranes, eyes,
  fontanels (infants), cardiovascular system,
  respiratory system, neurologic and muscular
  status.

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• Clinical measurement includes daily weights,
  vital signs, and fluid intake and output.

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Evaluation of Edema
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NANDA Nursing Diagnoses

• Deficient Fluid Volume
• Excess Fluid Volume
• Risk for Imbalanced Fluid Volume
• Risk for Deficient Fluid volume
• Impaired Gas Exchange

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NANDA Nursing Diagnoses

• Fluid and Acid-base Imbalances as Etiology
• Impaired Oral Mucous Membrane
• Impaired Skin Integrity
• Decreased Cardiac Output
• Ineffective Tissue Perfusion
• Activity Intolerance
• Risk for Injury
• Acute Confusion

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Desired Outcomes

• Maintain or restore normal fluid balance
• Maintain or restore normal balance of
  electrolytes
• Maintain or restore pulmonary ventilation and
  oxygenation
• Prevent associated risks
• Tissue breakdown, decreased cardiac output,
  confusion, other neurologic signs

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Nursing Interventions

• Monitoring
• Fluid intake and output
• Cardiovascular and respiratory status
• Results of laboratory tests
• Assessing
• Clients weight
• Location and extent of edema, if present
• Skin turgor and skin status
• Specific gravity of urine
• Level of consciousness, and mental status

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Nursing Interventions

• Fluid intake modifications
• Dietary changes
• Parenteral fluid, electrolyte, and blood
  replacement
• Other appropriate measures such as
• Administering prescribed medications and oxygen
• Providing skin care and oral hygiene
• Positioning the client appropriately
• Scheduling rest periods

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Promoting Fluid andElectrolyte Balance

• Consume 6-8 glasses water daily
• Avoid foods with excess salt, sugar, caffeine
• Eat well-balanced diet
• Limit alcohol intake
• Increase fluid intake before, during, after
  strenuous exercise
• Replace lost electrolytes

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Promoting Fluid andElectrolyte Balance

• Maintain normal body weight
• Learn about, monitor, manage side effects of
  medications
• Recognize risk factors
• Seek professional health care for notable signs
  of fluid imbalances

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Teaching Client to Maintain Fluid and
Electrolyte Balance

• Promoting fluid and electrolyte balance
• Monitoring fluid intake and output
• Maintaining food and fluid intake
• Safety
• Medications
• Measures specific to clients problems
• Referrals
• Community agencies and other sources of help
• Facilitating fluid intake

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Practice GuidelinesFacilitating Fluid Intake

• Explain reason for required intake and amount
  needed
• Establish 24 hour plan for ingesting fluids
• Set short term goals
• Identify fluids client likes and use those
• Help clients select foods that become liquid at
  room temperature
• Supply cups, glasses, straws
• Serve fluids at proper temperature
• Encourage participation in recording intake
• Be alert to cultural implications

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Practice GuidelinesRestricting Fluid Intake

• Explain reason and amount of restriction
• Help client establish ingestion schedule
• Identify preferences and obtain
• Set short term goals place fluids in small
  containers
• Offer ice chips and mouth care
• Teach avoidance of ingesting chewy, salty, sweet
  foods or fluids
• Encourage participation in recording intake

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Correcting Imbalances

• Oral replacement
• If client is not vomiting
• If client has not experienced excessive fluid
  loss
• Has intact GI tract and gag and swallow reflexes

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Correcting Imbalances

• Restricted fluids may be necessary for fluid
  retention
• Vary from nothing by mouth to precise amount
  ordered
• Dietary changes

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Oral Supplements

• Potassium
• Calcium
• Multivitamins
• Sports drink

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Evaluation

• Collect data as identified in the plan of care
• If desired outcomes are not achieved, explore the
  reasons before modifying the care plan

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