255 fluid and electrolyte

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255 fluid and electrolyte
2013-08-29 12:48:13
255 fluid electrolyte

255 fluid and electrolyte
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  1. two compartments involved in fluid distribution..
    • Intracellular compartment
    • extracellular compartment
    •      -interstitial spaces
    •      -plasma (vascular) compartment
    •      -transcellular compartment
  2. what is osmosis
    movement of water across a semipermeable membrane
  3. what is diffusion
    movement of particles from and area of higher concentration to an area of lesser concentration
  4. osmolarity =
    • osmolar concentration in 1 liter of solution
    • (mOsm/L)
  5. osmolality =
    a measure of the number of dissolved particles (solutes) in 1 kg (1liter) of water
  6. what are the three solutes that have the largest role in determining osmolality
    • sodium
    • glucose
    • urea
  7. what is normal serum osmolality
    275 - 295 mOsm/kg
  8. how does fluid shift in regards to the ECF and ICF
    fluid shifts from the area of lesser concentration to the area of greater concentration
  9. tonicity =
    ability of a solution to cause a change in water movement across a membrane due to osmotic forces
  10. hypotonic fluids make cells...
    • swell
    • the fluid has lesser concentration of solutes than plasma
  11. hypertonic fluids make cells....
    • shrink
    • the fluid has a greater concentration of solutes than plasma
  12. isotonic fluids cause ...
    no change in the size of the cell
  13. capillary hydrostatic pressure does what to fluid
    pushes water from intravascular to interstitia

    out of the capillary into the interstitial space
  14. capillary oncotic pressure is caused by
    plasma proteins
  15. capillary oncotic pressure does what to fluid
    pulls fluid into to intravascula space

    into the capillary from interstitial space
  16. lymphatics do what
    return fluid from the interstitial space to the systemic circulation
  17. why does IV therapy work
    because of osmosis
  18. fluids with the same osmolality as the plasma are termed
  19. solutions in which the solutes are less concentrated than the plasma are termed
  20. solutions with solutes in greater concentration than the plasma are termed
  21. where do administered isotonic IV fluids remain primarily?
    in the ECF
  22. when are isotonic fluids used
    • to replace ECF loos (diarrhea, vomiting, surgical blood loss)
    • when BP is low and to expand vascual volume quickly
  23. examples of isotonic fluids =
    • normal saline = 0,9% NaCl
    • Ringer's solution = contains sodium, potassium and calcium
    • Lactated Ringer's solution = sodium, potassium, calcium, lactate
    • D5 1/4 NS
  24. administration of hypotonic solutions results in what
    • water being pulled out of vessels into the cells and interstitial spaces
    • resulting in decreased vascular volume and increased cell water
  25. hypotonic fluids are used to prevent and treat what
    • cellular dehydration
    • hypernatremia = elevated sodium levels
  26. examples of hypotonic fluids =
    • D5W
    • 0.45% saline (1/2NS)
    • 0.225% saline (1/4NS)
  27. if D5W is isotonic in IV bag why is it a hypotonic fluid
    • the dextrose is rapidly metabolized once infused
    • 2/3 of water enters cells and 1/3 remains in ECF
  28. 1/2 NS means what
    • 0.45% saline
    • 1/2 of each liter infused mover into cells other half remains in ECF
  29. what is a plasma expander
    fluid that moves water from cell into plasma
  30. examples of hypertonic solutions
    • saline solutions > 0.9% ie 3% saline and 5% saline
    • dextrose solutions > than 5% ie 10% and 50%
  31. what is a colloid
    a large solute particel, such as protein or starch, that normally does not pass through cell and capillary membranes; they pull fluid from tissue into the vessels, increasing vascular volume
  32. what do colloid volume expanders do
    mobilize edema from the interstitial space into the vascular space
  33. examples of colloid volume expanders =
    • albumin
    • plasma protein fraction (plasmanate)
    • Dextran
    • Hetastarch (Hespan)
  34. what is normal fluid intake a day
    2500 ml
  35. water output is through
    • kidneys
    • stool
    • sweat
    • lungs
  36. what is the most objective measurement of fluid volume status
    daily weight
  37. what is the most important mechanism regulating intake of fluids
  38. what happens to elderly thirst
  39. hypodipsia
    decreased stimulus to drink
  40. polydipsia =
    excessive thirst
  41. treatment of fluid volume deficit in non acute situation
    • encourage fluid intake
    • probably not just water
  42. what lab values do you look at to see if patient needs blood
    • H & H
    • hemoglobin and hematocrit
  43. if you over hydrate someone you increase which capillary pressure
    hydrostatic pressure
  44. in isotonic contraction dehydration what fluid is lost
    water and sodium lost in equal proportions
  45. what causes isotonic dehydration
    vomiting, diarrhea, renal disease, diuretics
  46. hypotonic contraction dehydration - what fluid is lost
    loss of sodium, without corresponding loss of water
  47. hypertonic contraction dehydration - what fluid is lost
    loss of water without a corresponding loss of sodium
  48. what can cause hypotonic dehydration
    • diuretics and renal disease
    • because sodium is lost without correspondig loss of water
  49. what can cause hypertonic dehyration
    excessive sweating without replenishment, osomotic diuresis, burns
  50. normal urine output is
    • ml of fluid per kg per hour
    • or
    • 30 - 50 ml/hr
  51. what happens pathophysiolgically with hypotonic contraction
    ECF becomes hypotonic fluid shifts from ECF to ICF lowering plasma fluid volume


    becasue there is a loss of sodium without loss of water
  52. pathophysiology of hypertonic contraction
    ECF becomes hypertonic fluid shifts from ICF to ECF, causing cellular dehydration
  53. when can you assess JVD
    when head of bed is elevated at least 45 degrees JVD should be flat
  54. clinical manifestations of isotonic fluid volume excess
    • weight gain
    • edem
    • JVD
    • full bounding pulses
    • decreased serum osmolality < 275
  55. isotonic fluid volume excess can be casued by
    • decreased water and sodium elimination
    • excessive admin of IV fluids
    • excessive secretion of aldosterone
    • shift of fluids into the plasma
  56. accumulation of fluid in the interstitial space is caused by
    • increased hydrostatic pressure
    • decreased capillary oncotic ressure
    • increased capilary permeability - burns, allergies, inflammation, immune response
    • decreased lymphatic flow
  57. aldosterone is secreted in response to
    low sodium or high potassium levels
  58. ADH causes
    the reabsorption of water from the renal tubules
  59. decreased ADH release =
    water lost in urine
  60. water sodium and potassium balance is regulated by
    aldosterone (from adrenal cortex)
  61. aldosterone causes the reabsorption of
    Na and H2O and the elimination of K
  62. Aldosterone is secreted in response to
    low sodium or high potassium levels
  63. dependent edema is where
    • the location of the edema is dependent on the postion of the patient
    • ie if upright edema in legs and feet, if lying flat edema in back and butt
  64. 1+ edema =
  65. 4+ edema =
  66. if you give albumin to a pt with edema what would it do
    increase the oncotic pressure and pull fluid into the Intravascular space
  67. venous and lymph edema can be controlled by what
    elevation and compression
  68. third spacing =
    trapping of ECF in the transcellular space (peritoneal cavity -ascites, periorbital, pericardial)
  69. ADH is secreted in response to
    high serum osmolality or when blood pressure decreases or blood volume
  70. ADH is secreted from the
    posterior pituitary
  71. increased serum osmolality can be a
    water deficit or sodium excess
  72. low osmolality and or increased intravascula voume causes
    • lack of thirst --> decreased water intake
    • decreased ADH release --> water lost in urine
  73. decreased renal perfusion (because of low blood volume or low blood pressure)leads to release of
    renin and activation of the renin-angiotensin aldosterone system (RASS)
  74. electrolytes are
    charged particles called ions
  75. what is the chief intracellular cation
    potassium (the cell has 28X more potassium than the ECF)
  76. why does aldosterone hold onto Na and water and releases K
    to maintain electrical nuetrality
  77. is the potassium in blood a good indicator of the amount of potassium in body, why
    NO because most of potassium is inside the cell
  78. normal level of sodium is
    135-145 mEq/L
  79. sodium regulates
    extracellular fluid volume and osmolality
  80. sodium is important in
    the generation and transmission of nerve impulses and regulation of acid-base balance
  81. what is most predominant cation in the ECF
  82. what is the primary regulator of sodium balance
  83. avg adult daily requiremnt of sodium is
  84. sodium level <135 mEq/L =
  85. hyponatremia is common in elderly why
    decreased renal ability to conserve sodium
  86. hyponatremia can be caused by
    excessive sweating with water replacement instead of replacement with electrolyte/fluid
  87. one case where sodium does not follow Na is in
    the secretion of ADH
  88. why does excessive secretion of ADH cause hyponatremia
    because the body holds onto water and dilutes Na levels in the body
  89. clinical manifestations of hyponatremia =
    • N/V
    • anorexia
    • abdominal cramping
    • altered neurolgical functioning
    • coma
    • muscle twitching, tremors
  90. why would hypoaldosteronism casue hyponatremia
    because aldosterone makes you hold onto Na and water so if you do not have enough aldosterone you don't hold onto Na
  91. two big symptoms of hyponatremia =
    fluid volume deficit and neurological symptoms
  92. if dilutional hyponatremia how do you treat
    give loop diuretics
  93. most common cause of hypernatermia =
    kidneys not secreting Na
  94. hypernatremia is
    • too much Na
    • can be water loos or sodium gain
  95. hypernatremia SALT =
    • Seizures
    • Altered mental status
    • Lethargy; low grade fever
    • Thirst
  96. hyperaldosteronism can cause
    • hypernaremia
    • because aldosterone keeps water and Na
  97. hypernatremia is treated with
    • restricted sodium intake
    • give sodium free IV fluids
    • diuretics followed by water admin becasue diuretics get rid of sodium and water
  98. Diabetes insipidus =
    • not enough ADH
    • peeing out water not sodium
  99. is severe hypernatremia with hypovolemic you treat with
    hypotonic fluids
  100. i sever hypernatremia and hypervolemic you treat with