Med Surg Ch 17

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Med Surg Ch 17
2012-02-02 21:16:25

Fluids and Electrolytes
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  1. homeostasis
    • state of equilibrium in the internal environment of the body
    • maintenance of the composition and volume of body fluids within narrow limits of normal is necessary
  2. Adult percentage of water
    • 50-60%
    • is greater in men=more lean body mass
  3. older adult / infant percentage of water
    • 45-55% / 70-80% (respectively)
    • both are at higher risk for fluid related problems
  4. 2 major compartments of fluid in the body
    • intracellular
    • extracellular
  5. intracellular space
    • inside the cell
    • 2/3 of body water is located here
  6. extracellular space
    • interstitial fluid- fluid in the interstitium(space btwn the cells) and lymph
    • intravacular- fluid in blood(plasma)
    • transcellular fluid- fluid in specialized cavities (i.e. cerebrospinal fluid, fluid in GI tract, intraocular, etc)
    • 1/3 of body water is located here
  7. 1 Liter of water weighs
    2.2lbs (1kg)
  8. How many mL's are in 8oz?
  9. (True/False)
    The electrolyte composition varies between ECF and ICF but the overall concentration of electrolytes is the same in the two compartments.
    • True
    • (the concentrations of specific ions differ greatly)
  10. Main cation and anion in ECF
    • sodium(Na+)
    • chloride(Cl-)
  11. main cation and anion in ICF
    • potassium(K+)
    • phosphate(PO43-)
  12. movement of molecules from an area of high concentration to one of low concentration is called...
  13. when molecules combine with specific carrier molecules and speeds up the rate of diffusion
    ex. glucose transport
    facilitated diffusion
  14. process in which molecules move against the concentration gradient
    external energy (ATP) is required
    sodium moves out of the cell and potassium move into the cell to maintain the concentration difference using this mechanism (sodium-potassium pump)
    active transport
  15. Osmosis
    • movement of water btwn 2 compartments separated by a semipermeable membrane
    • water moves thru the membrane from dilute to more concentrated
    • no outside energy required
  16. Osmotic pressure
    • amount of pressure required to stop the osmotic flow of water (to stop the water from going to the more concentrated area)
    • determined by the concentration of solutes in solution
  17. Osmolality
    • indicates the water balance of the body
    • PLASMA osmolality- 275-295mOsm/kg
  18. >295 indicates concentration is too great or water content is too little and is called
    "water deficit"-hypovolemia
  19. <275 indicates concentration is too low or water content is too high and is called
    "water excess"-hypervolemia
  20. fluids with the same osmolality as the cell interior
  21. fluids in which the solutes are less concentrated than the cells
    • hypotonic
    • if a cell is surrounded by hypotonic fluid, water moves into the cell, causing it to swell
  22. fluids in which the solutes are more concentrated than cells
    • hypertonic
    • if a cell is surrounded by hypertonic fluid, water leaves the cell to dilute the ECF and the cell shrinks
  23. Hydrostatic pressure
    • the force within a fluid compartment
    • the major force that pushes water out of the vascular system at the capillary level
  24. Oncotic pressure
    • normal- 25 mm Hg
    • osmotic pressure exerted by colloids in solution
    • major colloid in vascular system contributing to total osmotic pressure is protein. protein attracts water pulling fluid from tissue space to vascular space
  25. capillary hydrostatic pressure and interstitial oncotic pressure moves water...
    OUT of the capillaries
  26. plasma oncotic pressure and interstitial hydrostatic pressure moves water ...
    INTO the capillaries
  27. edema
    • fluid accumulation in the interstitium
    • caused by increase in venous hydrostatic pressure <-- caused by fluid overload, heart failure, liver failure, obstruction of venous return to the heart
  28. First spacing
    normal distribution of fluid in the ICF and ECF compartments
  29. second spacing
    abnormal accumulation of interstitial fluid (i.e. edema)
  30. third spacing
    • when fluid accumulates in a portion of the body (transcellular fluid) from which it is not easily exchanged with the rest of the ECF
    • the fluid is trapped and unavailable for functional use
    • (i.e. ascites, edema associated with burns)
  31. hypothalamus
    • controls thirst response and ADH release from pituitary
    • if water deficit- stimulation of thirst response and ADH release
    • if water excess- suspression of both resulting in urinary excretion of water
  32. ADH (antidiuretic hormone)
    • regulates WATER retention by the kidneys
    • factors that stimulate ADH release: stress, nausea, nicotine, and morphine
    • SIADH- causes water retention
    • reduction of ADH release- causes diabetes insipidus: copious amounts of dilute urine excreted bc water isnt reabsorbed appropriately, excessive thirst, dehydration, hypernatremia
  33. glucocorticoids ans mineralocorticoids
    regulate both water and electrolytes
  34. cortisol
    • most abundant glucocorticoid
    • antiinflammatory effect
    • increase serum glucose levels
  35. aldosterone
    • mineralocorticoid
    • sodium retention
    • potassium excretion
  36. kidneys
    • primary organ for regulating fluid and electrolyte balance
    • produces ~1.5L of urine/day
    • impaired renal function results in: edema, potassium and phosphorus retention, acidosis
  37. Cardiac regulation
    peptide hormones are produced that act on renal tubules to promote excretion of sodium and water, resulting in decrease in blood volume and BP
  38. normal daily intake and output
  39. invisible vaporization from lungs and skin helping to regulate body temp
    insensible water loss: increases by exercise and increased body temp
  40. Gerontologic considerations
    • structural changes and decrease in renal blood flow
    • decrease in aldosterone
    • increase in ADH
    • increase loss of moisture thru skin-inability to respond to heat/cold changes
    • decreased thirst mechanism
    • musculoskeletal changes effect ability to get/hold onto fluids or use restroom
    • mental status changes
    • incontinent episodes
  41. fluid volume deficit (hypovolemia)
    • causes: diarrhea, fistula drainage, hemorrhage, polyuria, inadequate intake, shift of fluid from plasma into interstitial fluid
    • Tx: correct underlying cause and replace both water and any needed electrolytes, lactated ringers, isotonic (0.9%) sodium chloride for rapid replacement, or blood
  42. dehydration
    loss of pure water alone without corresponding loss of sodium
  43. fluid volume excess (hypervolemia)
    • causes: excess intake of fluids, abnormal retention- heart/kidney failure, shift of fluid from interstitial fliud into plasma fluid
    • Tx: treat cause, remove fliud w/o producing abnormal changes in electrolyte composition or osmolality of ECF, *diuretics and fluid restrictions, may have to restrict sodium intake, paracentesis
  44. Nursing implementation for fluid deficit
    • daily weights - 1lb (2.2kg) = 1Liter
    • I&Os - output should be at least 30mL
    • specific gravity (1.010-1.025): high-indicates concentrated urine
    • cardiovascular monitoring:
    • increased HR and vasoconstriction to make up for the less volume and keep the BP normal, orthostatic hypotension, if severe- weak, thready pulse
    • respiratory:
    • increased RR due to decreased tissue perfussion and resultant hypoxia
    • Neurologic:
    • altered sensorium bc of reduced cerbral tissue perfusion PEARRLA
    • LOC
    • voluntary muscle movement
    • muscle strength
    • reflexes
    • skin:
    • decreased skin turgor
    • cool and moist - vasoconstriction compensation
    • dry and wrinkled
    • dry mucous membranes
    • furrowed tongue
    • thirsty
  45. Nursing implementation for fluid excess
    • daily weights - 1lb (2.2kg) = 1 Liter
    • I&Os - output should be at least 30mL
    • specific gravity (1.010-1.025): low-indicates dilute urine
    • cardiovascular:
    • full and bounding pulse
    • JVD
    • increased BP
    • respiratory:
    • pulmonary congestion/edema
    • SOB
    • irritative cough
    • moist crackles
    • neurologic:
    • cerebral edema
    • LOC
    • voluntary muscle movement
    • muscle strength
    • reflexes
    • skin:
    • edema - cool skin bc fluid
    • hard/taut
  46. Sodium (Na+)
  47. main cation of EFC
    sodium - absorbed in GI tract
  48. role of sodium
    • maintains concentration and volume of ECF
    • generates/transmits nerve impulses
    • regulates acid-base balance
    • leaves trough urine, sweat, feces
  49. kidneys role regarding sodium
    • primary regulator of sodium balance
    • regulate ECF concentration by excreting or retaining water under the influence of ADH
    • *aldosterone: key role in sodium regulation by promoting sodium reabsorption
  50. hypernatremia
    • Na+ > 145
    • sodium gain or water loss
    • shifts water out of cell causing cellular dehydration/shrinkage
    • body's protection: thirst
    • caused by: altered LOC or inability to obtain fluids, ADH deficiency (i.e. diabetes insipidus) can result in diuresis, hyperosmolar tube feedings, hyperglycemia, excessive sweating, high fever
    • manifestations: specific gravity below 1.010 (dilute urine), intense thirst, twitching, lethargy, agitation, seizures, coma, syptoms accompanied by fluid deficit (i.e. ortho BP, weakness, tenting)
    • interventions: treat underlying cause, 5%D in H2O or hypotonic fluids, *reduce sodium levels slowly to avoid cerebral edema, administer diuretics, dietary sodium restrictions, daily weights
  51. hyponatremia
    • Na+ < 135
    • sodium loss or water gain
    • shifts water into cell causing cellular swelling
    • caused by: inappropriate hypotonic fluid therapy, SIADH - abnormal retention of water, losses thru GI tract, kidney, or skinactivation of thirst and ADH
    • manifestations: CNS- irritability, apprehension, confusion, seizures, coma, irreversible neuro damage
    • interventions: *fluid excretion, hypertonic solutions, vassopressin (drug that blocks ADH), daily weights
  52. Potassium (K+)
  53. major ICF cation
  54. hyperkalemia
    • K+ >5.0
    • sodium-potassium pump maintains this concentration pumping K+ into cell and Na+ out using ATP; magnesium needed for norm functioning
    • caused by: *renal failure, acidosis, cellular trauma (i.e. burn, crush injury, tumor lysis), exercise, severe infection
    • manifestations: increased cellular excitability, dysrhythmias, cardiac standstill, leg cramps, weakness/paralysis of skeletal muscles, abdominal cramping, diarrhea
    • interventions: eliminate potassium intake, increase potassium elimination (diuretics, increased fluid intake), force from ECF to ICF *using insulin or sodium bicarbonate, administer calcium gluconate, *ECG monitoring
  55. role of potassium
    • major factor of neuromuscular and cardiac function
    • cellular growth
    • acid-base balance
    • inverse relationship btwn Na+ and K+ - factors that cause sodium retention cause potassium loss in urine; "whatever sodium wants to do potassium does opposite"
    • sources: diet- fruits, dried fruits, vegetables
  56. role of kidneys regarding potassium
    primary route of potassium loss (90%), rest thru sweat and stool
  57. hypokalemia
    • K+< 3.5
    • caused by: abnormal losses from GI tract or kidneys, diuresis and elevated aldosterone (causes sodium retention and potassium loss), magnesium deficit, diarrhea, laxitive abuse, vomiting, ileostomy drainage, alkalosis shifts potassium ICF
    • manifestations: reduced cellular excitability, ventricular dysrythmias, weakness/paralysis of skeletal muscles, shallow respirations and resp arrest, hyporeflexia
    • interventions: potassium chloride supplements, increase dietary intake, *only give KCl if urine output of at least 0.5mL/kg/hr, **never give KCl via IV push, max concentration= 40, rate of admin: 10-20mEq/hr, assess IV site Qhr
  58. Calcium (Ca2+)
  59. role of calcium
    • absorbed in GI tract and kidneys
    • transmits nerve impulses, myocardial contractions, blood clotting, bone/teeth formation, muscle contractions
    • balance controlled by parathyroid hormone (increases absorption), calcitonin (decreases absorption; produced by thyroid), VitD
  60. hypercalcemia
    • Ca2+ > 11
    • caused by: *hyperparathyroidism, malignancy (bone destruction, tumor secretion), VitD overdose, prolonged immobilization, acidosis
    • manifestations: reduced excitability of muscles and nerves, hypoflexia, decreased memory, N/V, dysrhythmias, kidney stones
    • interventions: promote excretion with loop diuretic (Lasix), isotonic hydration, 3000-4000mL of fluid/day, weight bearing activities
  61. hypocalcemia
    • Ca2+ < 9
    • caused by: decreased PTH (thyroidectomy), pancreatitis, multi blood transfusions, low calcium diet, laxitive abuse, CKD, hypoparathyroidism, loop diuretics, alkalosis
    • manifestations:
    • increased nerve/muscle excitability
    • twitching
    • *tetany=signs of tetany:
    • Trousseau's (carpal spasm induced by BP cuff inflation)
    • Chvostek's (facial contraction with light tap in front of ear)
    • larangeal stridor, dysphagia, numbness and tingling around mouth or extremities, decreased HR
    • interventions: treat the cause, calcium supplements (not given IM bc sever local reactions), Vit D supplements, ECG monitoring
  62. phosphate (PO43-)
  63. primary ICF anion
  64. role of phosphorus
    • essential to function of muscle, RBCs, and nervous system
    • deposited with calcium for bone/teeth structure
    • needed for production of ATP
    • uptake of glucose, metabolism of carbs, proteins and fats
    • excreted mainly via kidneys
    • high phosphate causes low calcium
    • sources: dairy products
  65. hyperphosphatemia
    • PO43- > 4.5
    • caused by: ARF, chemotherapy, large Vit D intake, hypoparathyroidism
    • manifestations: hypocalcemia, tetany, calcified deposits
    • interventions: treat cause, dietary restrictions of dair products, hydration, correct hypocalcemia, calcium supplements
  66. hypophosphatemia
    • PO43- < 2.8
    • caused by: malnurishment/malabsorption, alcohol withdrawl, antacids, administration of glucose
    • manifestations: impaired cellular energy and oxygen delivery, depression, confusion, other mental changes, muscle weakness (resp depression), dysrhythmias, *cardiomyopathy
    • interventions: supplementations, dairy products, IV administration of sodium phosphate or potassium phosphate
  67. Magnesium
  68. role of magnesium
    • 50-60% in bone
    • coenzyme in metabolism of carbs and proteins
    • regulated by GI tract and kidneys
    • factors that regulate calcium (PTH) influence magnesium balance
    • sources: green vegetables, nuts, bananas, oranges, peanut butter, chocolate
  69. hypermagnesium
    • Mg2+ > 2.5
    • caused by: increased intake, renal failure, *pregnant women who take magnesium sulfate for mgmt of eclampsia
    • manifestations: depresses neuromuscular and CNS function, hyporeflexia, somnolence, *respiratory arrest followed by cardiac arrest
    • interventions: *prevention, *IV administration of calcium chloride or calcium gluconate, promote urinary excretion
  70. hypomagnesium
    • Mg2+ < 1.5
    • caused by: fasting or starving, *alcoholism - d/t insuff. food intake, prolonged parenteral nutrition w/o supplements, hyperglycemia, diarrhea, diuresis, NG suction
    • manifestations: confusion, *hyperreflexia, tremors, seizures, dysrhythmias
    • interventions: oral supplements, dietary supplements, IV/IM magnesium sulfate (*too rapid admin leads to resp/card arrest)
  71. isotonic solutions
    • Dextrose in water 5%
    • 0.9% saline
    • Dextrose in saline 5% in 0.225%
    • ringers/lactated ringers
  72. hypertonic solutions
    • Dextrose in water 10%
    • 3.0% saline
    • dextrose in saline 5% in 0.45%
    • dextrose in saline 5% in 0.9%
  73. hypotonic solutions
    • 0.45% saline
    • Dextrose in water 5% (physiologically)