1. Fluid, Electrolyte, and Acid-Base Balance
Chapter 34
Fluid, Electrolyte, and Acid-Base Balance

2. Physiology of Fluid and Acid-Base 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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3. Physiology of Fluid and Acid-Base Balance
Fluid Compartments
Cells
Blood vessels
Tissue space (interstitial space)
Space between the cells and blood vessels
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4. 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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5. 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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6. 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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7. 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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8. 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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9. 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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10. Functions of Body Water
Gives shape and form to cells.
Regulates body temperature.
Acts as a lubricant in joints.
Cushions body organs.
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11. Electrolytes
Compounds that, when dissolved in water or another solvent, form or dissociate into ions
Sodium (Na+)
Potassium (K+)
Calcium (Ca2+)
Magnesium (Mg2+)
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12. Electrolytes Promote normal neuromuscular excitability.
Maintain body fluid osmolarity.
Regulate acid base balance.
Distribute body fluids between fluid compartments.
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13. 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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14. 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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15. Movement of Body Fluids
Diffusion
Osmosis
Active Transport
Hydrostatic Pressure
Filtration
Colloid Osmotic Pressure
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16. Regulators of Fluid Balance
Fluid and Food Intake and Loss
Skin
Lungs
Gastrointestinal Tract
Kidneys
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17. 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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18. 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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19. 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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20. 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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21. 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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22. Factors Affecting Fluid and Electrolyte Balance
Age
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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23. Factors Affecting Fluid and Electrolyte Balance
Lifestyle
Stress
Exercise
Warm or humid environment
Diet
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24. 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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25. 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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26. 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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27. 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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28. Electrolyte Disturbances
Potassium
The normal range of extracellular potassium is narrow ( mEq/L).
Small deviations cause serious or life-threatening effects on physiologic functions.
A reciprocal relationship exists between sodium and potassium.
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29. 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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30. 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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31. 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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32. 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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33. Electrolyte Disturbances
Magnesium
Coenzyme in the metabolism of carbohydrates and proteins
Mediator in neuromuscular activity
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34. 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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35. 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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36. Electrolyte Disturbances
Hypophosphatemia is a decreased extracellular level of phosphorus.
Hyperphosphatemia is an increased extracellular level of phosphorus.
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37. 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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38. 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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39. Acid-Base Disturbances
Laboratory Data
Arterial blood gases
Blood pH
Bicarbonate ion concentration
Sodium, potassium, chloride levels
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40. 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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41. Assessment Health History
Clients receiving certain treatments, such as medications and IV therapy
Data specific to fluids
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42. Assessment Physical Examination Daily weight Vital signs
Intake and output
Edema
Skin turgor
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43. Assessment Physical Examination Buccal (oral) cavity Eyes
Jugular and hand veins
Neuromuscular system
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44. 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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45. Laboratory Data Osmolality
Measurement of the total concentration of dissolved particles (solutes) per kilogram of water
Serum osmolality
Urine osmolality
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46. Assessment Diagnostic and Laboratory Data Urine pH Serum albumin
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47. Nursing Diagnosis Excess Fluid Volume Deficient Fluid Volume
Risk for Deficient Fluid Volume
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48. Other Nursing Diagnoses
Impaired Gas Exchange
Decreased Cardiac Output
Risk for Infection
Impaired Oral Mucous Membrane
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49. 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 acid-base balance.
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50. 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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51. Implementation Monitor Daily Weight Measure Vital Signs
Measure Intake and Output
Provide Oral Hygiene
Initiate Oral Fluid Therapy
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52. Implementation Nothing by Mouth Restricted Fluids Forced Fluids
Maintain Tube Feedings
Monitor Intravenous Therapy
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53. 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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54. Intravenous Therapy Parenteral Fluids Hypotonic Isotonic Hypertonic
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55. Intravenous Therapy Equipment Administration Set Health Hazard
Intravenous Filters
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56. 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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57. 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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58. 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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59. Intravenous Therapy Flow Control Devices Manual flow-control devices
Electronic infusion devices
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60. Intravenous Therapy Managing IV Therapy Hypervolemia Infiltration
Phlebitis
Intravenous dressing change
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61. 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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62. Complementary Therapy
Herbs and certain foods
Naturopathic health care practitioners
Considerations for using complementary therapies with traditional medications
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63. Evaluation
The nurse should focus on the client’s responses when evaluating whether time frames and expected outcomes are realistic.
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