1. Fluid and Electrolytes
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2. Compartments Intracellular fluid (ICF) Extracellular fluid (ECF)
Intravascular (plasma)
Interstitial (between cells; lymph)
Transcellular
See Figure 16-2 in Lewis 6th ed.
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3. Intracellular Fluid (ICF)
Fluid located within cells
42% of body weight; 2/3 of body water
Potassium (K+): most prevalent intracellular cation
Phosphate (PO4-): most prevalent intracellular anion
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4. Extracellular Fluid (ECF)
Interstitial (between cells; lymph)
(Cl-): most prevalent anion
(Na+):most prevalent cation
2/3 of ECF is in interstitial
Intravascular (IV)
Within vascular space
Measured with blood tests
1/3 of ECF is intravascular
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5. Transcellular Small but important fluid compartment
Approximately 1 Litre
Includes
CSF
GI tract
Pleural space
Synovial spaces
Peritoneal space
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6. Mechanisms Controlling Fluid and Electrolyte Movement
Diffusion
molecules move from high to low concentration
Facilitated diffusion
involves carrier molecules
Active transport
movement against concentration gradient
requires energy
E.g.: keeping Na out and K in the cells (requires ATP)
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7. Mechanisms Controlling Fluid and Electrolyte Movement
Osmosis
H2O movement between compartments separated by membrane from area of high to low solute concentration
Membrane is permeable to water, not solutes
Hydrostatic pressure
Force within fluid compartment
Oncotic pressure= colloid osmotic pressure
Osmotic pressure exerted by colloids [e.g., protein] n solution; “pulls” fluid into vascular space
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8. Fluid Shifts: Plasma to interstitial space
Results in edema
Due to:
Elevated venous hydrostatic pressure
e.g., CHF, varicose veins
Decreased plasma oncotic pressure
e.g., low plasma protein r/t malnutrition
Elevated interstitial oncotic pressure
plasma proteins accumulated in interstitium, pulling water - e.g., burns
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9. Fluid Movement Between Extracellular and Intracellular
Excess water in ECF
Cells are more concentrated. Thus:
Water moves into cells → Cells swell
Water deficit in ECF : water is pulled from cells → Cells shrink
Both of above cause neurological symptoms
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10. Fluid Spacing First spacing Second spacing Third spacing
Normal distribution of fluid in ICF and ECF
Second spacing
Abnormal accumulation of interstitial fluid (e.g., edema associated with varicose veins, pulmonary edema)
Third spacing
Fluid accumulation in part of body where it is not easily exchanged with rest of ECF (e.g., edema due to burns, ascites [in peritoneal space)
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11. Regulation of Water Balance
Hypothalamic regulation (controls pituitary)
Pituitary regulation (ADH)
Adrenal cortical regulation (aldosterone – enhances Na and H20 retention)
Renal regulation
Cardiac regulation
Gastrointestinal regulation (fluid intake)
Insensible water loss
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12. Insensible Water Loss Invisible vaporization from lungs and skin
Approximately 900 ml per day is lost
No electrolytes are lost with insensible water loss
Excessive sweating is not an insensible loss. Diaphoresis leads to loss of water and electrolytes.
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13. Sodium
Plays major role in maintaining ECF concentration (osmolality) and volume
Main cation in ECF; primary determinant of osmolality (a measure of solute concentration)
Important in generation and transmission of nerve impulses
Important in acid-base balance
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14. Hypernatremia Hypernatremia due to Hypernatremia results in
Water loss or
Sodium gain
Hypernatremia results in
Hyperosmolality → water shifts out of cells → cellular dehydration
Primary protection against hypernatremia is thirst
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15. Hypernatremia
Manifestations include thirst, lethargy, agitation, seizures, and coma
Hypernatremia secondary to water deficiency often due to impaired LOC or inability to get fluids
Also due to deficiency in ADH
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16. Hypernatremia Management includes:
Treating the underlying cause
Hypotonic IV fluids if oral fluids cannot be ingested
Administering diuretics (promotes excretion of sodium)
Serum sodium levels must be reduced gradually to avoid cerebral edema
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17. Hyponatremia
Due to:
loss of Na-containing fluids, or
water excess (dilutional hyponatremia)
Hyponatremia → hypoosmolality → water moves into cells
Clinical manifestations include confusion, nausea, vomiting, seizures, and coma
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18. Hyponatremia If caused by water excess, fluid restriction is needed
If severe symptoms (seizures) occur, small amount of intravenous hypertonic saline solution (3% NaCl) is given
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19. Hyponatremia
If associated with abnormal fluid loss (diarrhea, polyuria, etc.):
fluid replacement with Na-containing solution (eg. Normal saline [0.9% NaCl])
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20. Potassium Potassium major ICF cation Potassium is necessary for
Transmission and conduction of nerve impulses
Normal cardiac rhythms
Skeletal muscle contraction
Acid-base balance
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21. Potassium Critical to action membrane potential Sources of potassium
Fruits and vegetables (bananas and oranges)
Salt substitutes
Potassium medications (PO, IV)
Stored blood
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22. Hyperkalemia Causes Increased retention Renal failure
Potassium sparing diuretics
Increased intake
Mobilization from ICF
Tissue destruction
Acidosis
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23. Hyperkalemia Clinical Manifestations
Skeletal muscles weak or paralyzed
Ventricular fibrillation or cardiac standstill
Abdominal cramping or diarrhea
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24. Nursing Management of Hyperkalemia
Eliminate oral and parenteral K intake
Increase elimination of K (diuretics, dialysis, Kayexalate)
Force K from ECF to ICF with IV insulin (or sodium bicarbonate if hyperkalemia is due to acidosis)
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25. Hypokalemia Causes Increased loss Certain diuretics GI losses
Associated with Mg deficiency
Movement into cells
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26. Hypokalemia Clinical Manifestations
Potentially lethal ventricular arrhythmias
Increased digoxin toxicity in those taking the drug
ECG changes
Skeletal muscle weakness and paralysis
Muscle cell breakdown
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27. Hypokalemia Clinical Manifestations
Decreased GI motility
Altered airway responsiveness
Impaired regulation of arterial blood flow
Diuresis
Hyperglycemia
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28. Nursing Management of Hypokalemia
Replacement PO or IV
Never push IV
Painful in peripheral veins
Never give with anuric renal failure
Teach prevention methods (e.g. diet)
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29. Electrolyte Disorders Summary Signs and Symptoms
Excess
Deficit
Sodium (Na)
Hypernatremia
Thirst
CNS deterioration
Increased interstitial fluid
Hyponatremia
Potassium (K)
Hyperkalemia
Ventricular fibrillation
ECG changes
CNS changes
Hypokalemia
Bradycardia
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30. Electrolyte Disorders Signs and Symptoms
Excess
Deficit
Calcium (Ca)
Hypernatremia
Thirst
CNS deterioration
Increased interstitial fluid
Hypocalcemia
Tetany
Chvostek’s, Trousseau’s Muscle twitching
CNS changes
EKG changes
Magnesium (Mg)
Hypermagnesemia
Loss of deep tendon reflexes (DTRs)
Depression of CNS
Depression of neuromuscular function
Hypomagnesemia
Hyperactive deep tendon reflexes
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31. Protein Imbalances
Plasma proteins(especially albumin) are important determinants of plasma volume
Hyperproteinemia is rare
Occurs with dehydration-induced hemoconcentration
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32. Hypoproteinemia Caused by Anorexia Malnutrition Starvation Fad dieting
Poorly balanced vegetarian diets
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33. Hypoproteinemia Poor absorption d/t GI malabsorptive diseases
Inflammation → protein can shift out of intravascular space
Hemorrhage
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34. Hypoproteinemia: Clinical Manifestations
Edema (b/c insufficient oncotic pressure to “hold” water in vascular space)
Slow healing
Anorexia
Fatigue
Anemia
Muscle loss
Ascites (same reason as edema)
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35. Hypoproteinemia Management High-carbohydrate, high-protein diet
Dietary protein supplements
Enteral nutrition or total parenteral nutrition
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36. Extracellular Fluid Volume Imbalances
Hypovolemia due to:
loss of normal body fluids (diarrhea, fistula drainage, hemorrhage)
decreased intake
or plasma-to-interstitial fluid shift
Hypervolemia due to:
excessive intake of fluids
abnormal retention of fluids (CHF)
or interstitial-to-plasma fluid shift
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37. Extracellular Fluid Volume Imbalances
Hypovolemia:
Treat with fluid replacement (NS, Ringer’s, blood)
Hypervolemia
Remove excess fluid (diuretics, dialysis)
Fluid restriction, sodium restriction
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38. Nursing Diagnoses: Hypervolemia
Excess fluid volume
Ineffective airway clearance
Risk for impaired skin integrity
Disturbed body image
PC: pulmonary edema, ascites
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39. Nursing Diagnoses: Hypovolemia
Fluid volume deficit
Decreased cardiac output
PC: hypovolemic shock
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40. Nursing Implementation for Volume Imbalances
Cardiovascular status (BP, pulse strength, JVD, HR, orthostatic hypotension)
Respiratory status (crackles, RR)
Neurological function
Daily weights (1 kg = 1000 ml)
Skin assessment (turgor, edema)
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41. Nursing Implementation for Volume Imbalances
Neurologic function
LOC
PERLA
Voluntary movement of extremities
Muscle strength
Reflexes
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42. IV Fluids Purposes Maintenance Replacement
When oral intake is not adequate
Replacement
When losses have occurred
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43. Solution Types Hypotonic Provides more water than electrolytes
Dilutes ECF, thus water moves from ECF → ICF
Examples: 0.45 NaCl
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44. Solution Types Isotonic Same osmolality as ECF
Expands only ECF (what goes in ECF stays in ECF; no shifting to ICF)
Examples: Normal saline (0.9% NaCl), Lactated Ringers (Ringer’s Lactate)
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45. Solution Types Hypertonic More concentrated than ECF
Expands ECF volume
Increased osmolality draws water from cells into ECF
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46. D5W Isotonic A source of calories
But becomes hypotonic after dextrose is metabolized b/c only water remains
A source of calories
A source of “free water: (as above b/c of metabolism of glucose)
Moves into ICF
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47. D5W
Prevents ketosis
Supports edema formation – do not use in clients with cerebral edema!
Decreased chance of IV fluid overload
Usually compatible with medications
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48. Normal Saline (NS; 0.9% NaCl)
Isotonic
No calories
More NaCl than ECF (could cause hypernatremia, hyperchloremia)
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49. Normal Saline (NS; 0.9% NaCl)
Expands IV volume
Preferred fluid for immediate response
Risk for fluid overload higher
Does not change ICF Volume
Blood products
Compatible with most medications
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50. Lactated Ringer’s Isotonic
More similar to plasma than NS (b/c has electrolytes)
Commonly used postoperatively
Expands ECF, IV
Common replacement fluid
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51. D5 ½ NS
Hypertonic (becomes Hypotonic in body after dextose is absorbed)
Common maintenance fluid
KCl added for maintenance or replacement
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52. D5 ½ NS (Hypertonic) Provides calories Moves into ICF
Prevents ketosis
Moves into ICF
Usually compatible with medications
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53. Plasma Expanders (Hypertonic)
Pull fluid from interstitium into vascular space
Colloids
Packed RBCs
Albumin
Plasma
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