Electrolytes and Fluids - Fluid Mgmt & Osmolality

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Electrolytes and Fluids - Fluid Mgmt & Osmolality
2015-01-14 14:47:11

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  1. A normal adult has ~___L of fluid
    42L of fluid
  2. Distribution of total body fluid (TBF) is estimated as what percentage of lean body weight (LBW) in men? In women?
    • Men - 60% LBW
    • Women  50% LBW
  3. Distribution of total body fluids include ___% of TBF being intracellular and ___% being extracellular.

    Extracellular space includes __% interstitial and __% intravascular space
    60% intracellular, 40% extracellular

    Extracellular: 75% interstitial, 25% intravascular
  4. Intracellular space is highly permeable to what? Extracellular space is permeable to all solutes except what?
    • Intracellular - water
    • Extracellular - all solutes except proteins
  5. Lactated ringers (LR) consists of what? (5)
    • Na
    • Cl
    • Lactate
    • K
    • Ca
  6. For 0.9% NaCl, LR, and D5W, what % of fluid can be found in intracellular, extracellular, and intravascular space?
    0.9% NaCl and LR: 0% intracellular, 100% extracellular, 25% intravascular

    D5W ~ free H2O: 60% intracellular, 40% extracellular, 25% intravascular
  7. Between 0.9% NaCl, LR, D5W, which fluids should NOT be given to patients w/elevated ICP (intracranial P)?
    D5W d/t crossover of glucose into cerebral cells
  8. Colloids include what 4 fluids?
    • 1. pRBC's
    • 2. Pooled human plasma (5% and 25% albumin, 5% plasma protein fraction)
    • 3. Dextran (semisynthetic glucose polymers)
    • 4. Hetastarch ( semisynthetic hydroxyethyl starch)
  9. What GENERAL type of fluid is too large to cross capillary membranes and remain 100% in intravascular space?
  10. Which SPECIFIC type of fluid causes a shift from interstitial to intravascular fluid d/t 5x increased oncotic P than normal plasma?
    25% albumin (100ml of administered fluid will result in 500ml fluid into intravascular space)
  11. 25% albumin should be AVOIDED in patients needing ______ ___________, and why? Patients that may benefit from this fluid include those who need __________ of fluids.
    Avoid in pt's who need fluid resuscitation d/t shifting out of IS space causing dehydration.

    This will benefit in those who need redistribution of fluids (ascites, pleural effusions)
  12. What are 2 possible reasons that could result in intravascular fluid depletion? When do signs/symptoms start to occur?
    Hemorrhage or septic shock

    S/Sx start to occur when 15% of blood volume is lost = 750ml (of 5L) OR when it shifts out of intravascular space (severe sepsis)
  13. What are 2 main differences in fluid administration processes between fluid resuscitation and maintenance of fluids?
    • 1. Fluid resuscitation occurs rapidly in 500ml to 1000ml boluses
    • 2. ...and is administered via central IV cathether
    • (Maintenance is continuous IV infusion via peripheral IV catheter)
  14. What are the NINE s/sx of intravascular volume depletion? (HINT: 3 symptoms, 5 objective signs, 1 "wait and see")
    • 1. Dry mucous membranes
    • 2. Decreased skin turgor
    • 3. Dizziness
    • 4. Tachycardia >100bpm
    • 5. Hypotension SBP<80mmHg
    • 6. Orthostatic changes in HR or BP
    • 7. Inc'd BUN/SCr ratio >10:1
    • 8. Dec'd UOP
    • 9. Improvement in HR or BP after 500ml-1L fluid boluses
  15. Although crystalloids are recommended during fluid resuscitation, LR was theoretically preferred d/t what? Why does this NOT matter during shock?
    LR preferred d/t lactate metabolizing to bicarbonate and useful in metabolic acidosis

    Doesnt matter b/c lactate metabolism impaired during shock (ineffective source of bicarbonate)
  16. What 3 common scenarios would colloids be considered over crystalloids during fluid resuscitation?
    • 1. When ~4-6L crystalloids have failed to achieve hemodynamic goals OR there is clinically significant edema from crystalloid
    • 2. Specifically, albumin may be considered in patients with albumin <2.5g/dL who require large volumes of resuscitation fluids
    • 3. 25% albumin considered in conjunction w/diuretics for clinically signif edema (i.e. pulm edema -->resp failure) AND albumin <2.5g/dL when appropriately dosed diuretics are ineffective
  17. What are the 2 formulas for daily maintenance IV fluids for adults and children?
    • 1st:
    • 100ml/kg for 1st 10kg
    • 50ml/kg for next 10kg
    • 20ml/kg for every kg over 20kg

    2nd (adults only): 20-40ml/kg/day
  18. What are the typical maintenance IV fluids for patients?
    D5W with 0.45% NaCl plus 20-40mEq of KCl per liter
  19. What is the normal plasma osmolality between?
  20. Whats the diff b/w osmolality and osmolarity? Whats the diff for plasma?
    • Osmolality: Osm solute/kg solvent
    • Osmolarity: Osm solute/L solution

    No difference in plasma of both... only ~1%
  21. What is the estimated equation for plasma osmolality?
    mOsm/kg: (2xNa) + (GLU/18) + (BUN/2.8)
  22. What occurs to the cell and plasma when there are increases or decreases in plasma osmolality?
    Inc'd plasma osmolality: Shift out into plasma, cells dehydrate and shrink

    Dec'd plasma osmolality: Shift INTO cell, cells overhydrate and swell
  23. What occurs to cells when patients receive hypertonic, and hypotonic fluids? For hypotonic, at which osmolarity does the shift occur?
    • Hypertonic: Cells shrink
    • Hypotonic osmolarity <150mOsm/L: Cells swell
  24. Explain what occurs to RBC's, and brain cells when hypotonic fluids are given. For brain cells, when does it typically begin?
    • RBC: Swell and rupture - hemolysis
    • Brain cells: Cerebral edema and herniation, occurring in less than 2 days w/hypoNa
  25. Of the four, which electrolyte has a valence of 2? What does this do to equivalent weight (g)?
    Na, K, Cl, Mg.
    • Mg2+
    • Valence of 2, so MW is divided by 2
  26. Of the three, which has 3 oSm?
    NaCl, KCl, CaCl2
  27. How do you convert 23.4% NaCl to g/ml?
    23.4% = g/100ml = 23.4g/100ml
  28. What is the importance of osmotic coefficient (used to calculate osmolarity of IV fluids b/c salt forms dont completely dissociate in solution).
    Not considered clinically relevant, but for NS, it is 0.93 (and thus 0.9% NaCl)