Fluid & Electrolyte Balance

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Fluid & Electrolyte Balance
2011-04-02 16:49:51

Fluid & Electrolyte Balance
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  1. Active Transport
    • a process that requires metabolic activity and the expenditure of energy to move materials across cell membranes
    • requires ATP
  2. Albumin
    a simple form of protein that is water soluble
  3. Aldosterone
    • a hormone released by the adrenal cortex in response to the sensation of a low blood volume
    • it starts a process where the body retains salts thereby causing the body to retain water, thus increasing the circulating blood volume
  4. Angiotensin
    • a protein whose presence in the blood promotes aldosterone secretion
    • tends to raise the BP
  5. Anion
    • a negatively charged electrolyte
    • Cl-
    • HCO3--
    • SO4--
    • HPO4--
    • Proteinate
  6. Antidiuretic Hormone (ADH)
    • a hormone released by the posterior pituitary gland that decreases the production of urine by increasing the reabsorption of water
    • it is released in response to the sensation of a decreased blood volume or increased sodium level
    • ADH causes vasoconstriction and an increase in blood volume
  7. Cation
    • a positively charged electrolyte
    • Na+
    • K+
    • Ca++
    • MG++
    • H+
  8. Colloid
    • not true solutions
    • suspensions of proteins or starches that remain in the intravascular space and increase the colloid osmotic pressure
    • referred to as plasma expanders
    • examples are dextran, hetastarch, plasmanate and albumin
    • albumin is extracted from plasma and contains globulins and other proteins
  9. Crystolloids
  10. Dehydration
    to lose a large amount of water from the body
  11. Diabetes Insipidus
    a condition in which the kidneys are unable to conserve water
  12. Diffusion
    • the movement of a solute (particles) across a semipermeable membranes from an area of higher concentration to an area of lesser concentration so that there is an even distribution of solute on each side
    • is the movement of particles
    • affected by size of the molecule, temperature of the solution, agitation and concentration
  13. Edema
  14. Electrolyte
    • an element or compound that when dissolved in water or other solvent, dissociates into ions and is able to conduct an electric current
    • promotes neuromuscular excitability
    • maintains body fluid osmolality
    • regulation of H+ balance
    • maintenance of bodily fluid distribution b/t compartments
  15. Extracellular Fluid (ECF)
    • the fluid located outside the cells
    • 30% of body fluid is ECF
    • found in- intravascular, interstitial and transcellular
  16. Filtration
    • the process in which water and diffusible substances move together in response to fluid pressure
    • example of the filtration process is active in capillary beds where hydrostatic pressure differences determines the movement of water
  17. Fluid Volume Deficit
    *water and electrolytes are LOST in equal proportions

    • *caused by
    • losses from the GI system as in diarrhea, vomiting or drainage from fistulas or tubes
    • loss of plasma or whole blood such as with burns or hemorrhage
    • excessive perspiration or fever
    • decreased oral intake of fluids
    • use of diuretics

    • *assessment finding include
    • postural hypotension
    • tachycardia
    • dry mucous membranes
    • poor skin turgor
    • thirst
    • confusion
    • rapid weight loss
    • slow vein filling
    • lethargy
    • oliguria
    • weak pulse

    • *lab finding
    • specific gravity > 1.025
    • increased Hct
    • increased BUN > 25

    • *defining characteristics include muscular weakness in the upper body
    • decreased skin turgor
    • dry mucous membranes
    • soft/sunken eyeballs
    • tachycardia, weak thready pulse
    • peripheral vein refill > 5 sec
    • orthostatic hypotension/hypertension
    • narrow pulse pressure
    • flattened neck veins in supine position
    • constipation
    • elevated specific gravity bc there is less water so the urine is more concentrated
    • elevated Hct bc the blood is thicker due to the lack of fluid
  18. Fluid Volume Excess
    *water and Na RETAINED in isotonic proportion

    • *caused by
    • CHF
    • renal failure
    • cirrhosis of the liver
    • increased serum aldosterone and steriod levels
    • excessive Na intake or administration

    • *assessment findings
    • rapid weight gain
    • edema
    • hypertension
    • polyuria
    • neck vein distension
    • increased venous pressure
    • crackles in lungs

    • *lab findings
    • decreased Hct
    • decreased BUN <10

    • *defining characteristics
    • weakness and fatigue
    • body edema
    • sudden weight gain
    • peripheral vein emptying < 5 sec
    • jugular venous distention
    • progressively worsening dyspnea, tachypnea due to pulmonary edema
    • crackles/ rales in the lungs
    • specific gravity decreased due to dilute urine
    • decreased Hct due to watery blood
    • bounding pulse with possible s3 gallop
    • hypertension
    • high or low urine output depending on renal fx
  19. Hemodilution
  20. Hydrostatic Pressure
    • the force of the fluid pressure outward against a surface
    • the pressure exerted by the liquid
  21. Hypertonic
    • a solution of higher osmotic pressure
    • the pressure inside the cell is hyper (higher), thus the fluid moves out of the cell (from higher to lower) and thus expands the body's fluid volume without causing a fluid shift from one compartment to another
  22. Hypotonic
    • a solution of lower osmotic pressure
    • the pressure inside the cell is hypo (lower) and thus the fluid moves into the cell causing it to enlarge
  23. Hypovolemia
  24. Insensible Water Loss
    • Not measurable
    • losses from skin and lungs
  25. Interstitial Fluid
    • the fluid b/t cells and the outside of blood vessels
    • anything that is not intervascular
  26. Intracellular Fluid (ICF)
    • the fluid inside the cells
    • 70% of bodily fluid
  27. Ion
    an electrically charged particle
  28. Isotonic
    a solution with the same osmolarity as blood plasma
  29. Milliequivalent (mEq)
    • the number of grams of solute dissolved in 1 gram of a normal solution
    • an indicator of chemical combining power
  30. Oncotic Pressure (Colloid Osmotic Pressure)
    • the osmotic pressure of a colloid in a solution
    • example- proteins like albumin exert pressure which tends to keep fluid in the transvascular compartment
  31. Osmolality
    • the osmotic pressure of a solution
    • nl- 280-295 mOsm/kg
    • describes bodily fluids
  32. Osmosis
    • the movement of a pure solvent, such as water, through a semipermeable membrane from an area of lesser solute concentration to an area of greater solute concentration.
    • water moves bc the membrane doesn't allow the solute to pass through, but it allows the solvent (water/fluid) to pass
  33. Semi-Permeable Membrane
  34. Sensible Water Loss
    • Measurable losses
    • from urine, feces and wound drainage
  35. Specific Gravity
    • reflects the size and weight of substances in the urine in comparison to distilled water
    • nl= 1.010 to 1.028
  36. Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
    condition caused by excessive release of ADH which results in hyponatremia or fluid volume overload
  37. Tonicity
    it is a comparative term used to express the relationship bt fluid compartments in terms of their concentration
  38. Vascular Space
    space inside the vessel
  39. Review the compartments of the body in which fluid is found.
    • Intracellular: the fluid inside the cells; 70% of the body's fluid
    • Extracellular: all the fluid that isn't located inside the cell; 30% of the body's fluid; Intravascular is inside the vessels (plasma); Interstitial is the fluid b/t the cells and the tissues; Transcellular is fluid in odd spaces (csf, synovial joint fluid)
    • *when in balance, water and electrolyte are in their proper amounts and the fluids are distributed 70(ICF)/30(ECF). If excess, we eliminate the fluid/electrolyte, if less, we seek to add them to achieve homeostasis
  40. Explain the fluid regulatory mechanism of the hypothalamus, posterior pituitary gland, adrenal cortex and kidneys.
    • Bodily fluids are regulated by fluid intake, hormonal controls and fluid output, the balance of these three are referred to as homeostasis.
    • Fluid intake is regulated by the thirst mechanism which is located in the hypothalamus. For example, if you eat potato chips, the osmoreceptors sense an increase in osmolarity due to the salt on the chips, then the hypothalamus is stimulated and we want to drink. The hypothalamus is also stimulated when there is excess fluid loss or hypovolemia, such as the case of vomiting or hemorrhaging.
    • ADH is released by the posterior pituitary gland in response to changes in blood osmolarity. When the hypothalamus senses and increase in osmolarity, ADH is released. ADH causes the renal tubules to allow water to pass (stops urine production) returning it to systemic circulation which dilutes blood and lowers osmolarity. When homeostasis is reached, normal urine output is resumed
    • Aldosterone is released by the adrenal cortex in response to increased potassium levels or as part of the renin-angiotensin cycle. Aldosterone stimulates the renal tubules to save salt and excrete potassium. Salt retention leads to water retention.
    • Renin acts to produce angiotensin 1 & 2 which cause vasoconstriction and increase blood flow to the kidneys, improving renal perfusion.
    • Fluid output occurs through 4 organs of water loss, the kidneys, the lungs, the skin and the GI tract. The kidneys are the major regulator organ of fluid balance, the GI tract also plays a vital role in fluid regulation (normal loss is 100-200ml/day but this can rise dramatically with diarrhea, etc.
  41. Identify the ways in which osmotic and hydrostatic pressure influence the movement of fluids through the membranes.
    osmotic pressure is the drawing power for water (water movement) and it depends on the number of molecules in a solution; a solution with a high solute concentration has a high osmotic pressure and draws water to itself (requires more water to equal); this is a hypertonic solution; a hypotonic solution moves fluid into the cells because the cells have the higher osmotic pressure

    filtration is able to occur in the capillary bed due to the pressure differences b/t hydrostatic pressure on the arterial and venous side of the bed; the pressure on the arterial side is 32mmHg, the pressure on the venous side is 12mmHg, the pressure inside the capillary bed is 22mmHg; the pressure changes from the arterial end to the venous end cause the blood to move out (on the arterial side, pushing the nutrients and the good stuff out) or drawing in the blood (on the venous end, drawing in the waste and the bad stuff)
  42. Describe the mechanism of active transport.
    • active transport is the movement of particles across membranes in a process that requires the expenditure of energy
    • this allows cells to admit larger molecules than they would otherwise be able to admit, or to move particles from areas of lesser concentration to greater concentration against the concentration gradient.
    • active transport is how cells absorb glucose and other substances to carry out metabolic activity (Na/K pump)
    • this process makes it possible to keep a higher concentration of K in the ICF and Na in the ECF
  43. Explain the role of plasma proteins in fluid balance.
    • the osmotic pressure of blood is affected by plasma proteins, esp albumin.
    • albumin exerts colloid osmotic pressure, which tends to keep fluid in the intravascular compartment
    • at the venous end of the capillaries, this oncotic pressure and decreased venous hydrostatic pressure draw water and waste back into the capillaries to be filtered through the kidneys.
    • at the arterial end of the capillaries hydrostatic pressure is greater than colloid pressure which causes the fluids and diffusable solutes to move out of the capillary and into the interstitial space
    • the excess fluids and solutes in the interstitial space are drawn up by lymph vessels into the intervascular space
  44. Describe the following categories of fluid balance disturbances including the causes and assessment finding of each.
    Isotonic Imbalances:
    -Fluid Volume Deficit
    -Fluid Volume Excess
    Third Space Syndrome
    Osmolar Imbalances:
    -Hyperosmolar Imbalance (dehydration)
    -Hypoosmolar Imbalance (water excess)
    • Fluid Volume Deficit: *SEE ABOVE*
    • Fluid Volume Excess: *SEE ABOVE*
    • Third Space Syndrome: fluid gathers where it normally never does, ex is a distended abdomen


    Hyperosmolar Imbalance: Dehydration

    • *caused by
    • diabetes
    • interruption of the thirst drive
    • osmotic diuresis
    • administration of hypertonic parental fluids or tube feeding formulas

    • *assessment finding
    • dry and sticky mucous membranes
    • flushed and dry skin
    • thirst
    • elevated body temp
    • irritability
    • convulsions
    • coma

    • *lab findings
    • increased serum Na >145
    • increased serum osmolality > 295

    Hypoosmolar Imbalance: Water excess

    • *caused by
    • SIADH (head injuries can cause a continuous release of AHD causing water retention
    • excess water intake

    • *assessment finding
    • decreased LOC
    • convulsions
    • coma

    • *lab findings
    • decreased serum Na levels < 135
    • decreased serum osmolality < 275
  45. Determine the following:
    -cation or anion?
    -primarily intracellular or extracellular?
    -fx in the body?
    -regulated chiefly by?
    -nl lab value?
    -deficit is called?
    -deficit is caused by?
    -defining characteristics of deficit include?
    -excess is called?
    -excess is caused by?
    -defining characteristics of excess include?
    -food sources where it exists in high amounts?

    for each electrolyte:
    -Sodium (Na+)
    -Calcium (Ca++)
    -Chloride (Cl-)
    -Potassium (K+)
    -Magnesium (Mg++)
    -Phosphate (PO4-)
    *see chart*
  46. Discuss variables affecting fluid and electrolyte balance.
    • age
    • acute illness
    • respiratory disorders
    • head injury
    • chronic illness
    • environmental factors
    • diet
    • lifestyle
    • meds
  47. Identify common nursing interventions for pt's with fluid and/or electrolyte disturbances.
    • daily weights and measurements of I&O
    • enteral replacement of fluids
    • restriction of fluids
    • parenteral replacement (IV) of fluids and electrolytes
  48. Describe the four classifications of IV fluids.
    -Blood & Blood Products
    • Crystalloids: true solutions that pass freely though a semipermeable membrane
    • Colloids: not true solutions, they are suspensions of proteins or starches that remain in the intravascular space and increase the colloid osmotic pressure
    • Blood & Blood Products: used to increase circulatory volume after trauma or sx, correct anemia or provide a specific component to correct a deficiency
    • Lipids: are fat emulsions and are commonly used as part of TPN to supplement nutritional needs
  49. Describe the three types of crystalloid solutions, giving examples of each type, indications for its use and expected effects on the pt's fluid status:
    • Hypotonic: is a solution that is less concentrated than the blood, causes water to move out of the intravascular space and into the cells, example are 1/2 NS, 1/3 NS, D5W after its been infused
    • Hypertonic: is a solution that is more concentrated than the blood, causes water to move out of the cells and into the intravascular space causeing shrinkage of the cells, examples are D5NS, D10W and 3% saline
    • Isotonic: is a solution that is about the same concentration as the blood, they tend to stay in the intravascular compartment and examples include NS, lactated ringers and D5W before it has been infused
  50. Describe nursing interventions for a pt receiving fluid replacement.
  51. Identify nursing dx related to health problems associated with fluid & electrolyte imbalance.
    -Fluid Volume Deficit
    -Fluid Volume Excess
  52. Describe the action, indication for use, side effects, nursing implications and pt teaching for the administration of the following electrolyte replacements:

    Potassium Chloride
    -Kay Ciel

    Calcium Gluconate

    Magnesium Chloride

    Magnesium Oxide

    Calcium Carbonate
    *see chart*
  53. Identify nl lab values for the following and discuss implications of low and high values:
    -Serum Osmolality
    -Urine Specific Gravity
    -Blood Urea Nitrogen
    • Serum Osmolality: 275-295
    • Urine Specific Gravity: 1.010 to 1.028
    • Blood Urea Nitrogen: 8-20
    • Creatinine: m 0.6-1.2, f 0.5-1.1
  54. Calculating Serum Osmolality
    • Na x 2 + BUN/3 + Glucose/18
    • nl= 275-295