Fluids Flashcards
IBW calc men
50kg + (2.3* inches over 60”)
IBW calc women
45.5kg + (2.3* inches over 60)
Adjusting body weights
-Dosing Body Weight
-Nutrition Body Weight
-IBW is almost never the correct choice for electrolytes?
Dosing Body Weight (DBW)
Nutrition Body Weight (NBW)
IBW + 0.25(wt-IBW)
-use if ABW>130% of IBW
-use to calc fluid, electrolyte, nutrition parameters
Fluid Distribution
-intracellular (2/3)
-extracellular (1/3)
-*transcellular
-60% of body weight
Extracellular fluid distribution
-3/4 interstitial (surrounds cell)
-1/4 Intravascular (plasma)
Transcellular Fluid Distribution
-spine
-lymph
-joints
-eyes
-not subject to daily gains and losses
Body Water comp adults
-Men: 50-60%
-women: 45-55%
Body Water Comp and age
-high in infants (75-90%)
-lower in elderly
-dectrases with age
-skeletal muscle mass declines
-fat proportion may increase
Fluid Balance maintains:
-body temp
-cell shape
-transport
-nutrients
-gases
-wastes
Fluid balance key organs
-skin
-lungs
-kidneys
Fluid intake
-liquids
-solids
-meds
Fluid losses
-sensible (measurable)
-insensible (immeasurable)
Average Sensible Fluid Loss
-Urination
-Defecation
-Wounds
~1-1.5 L/day
Insensible Fluid Loss
-skin
-lungs
~1L/day
Additional Fluid losses
-NG output
-Vomit
-Diarrhea
-burns
-fistulas
-drains
-bleeding/wounds
Volume Regulation mediated by
-kidneys
-thirst
-hormone changes
Electrolytes lost in NG output
-sodium and chloride
-losss of chloride can lead to alkalosis
Electrolytes lost in diarrhea
-bicarbonate (HCO3) (bases)
-leads to acidosis
Isotonic
-275-290 mOsm/L
-prevents fluid shift
-equal concentration
HYPOtonic
<275
-less concentrated than ECF
-Fluid moves INTO cell
-hypO = swell
HYPERtonic
->290
-more concentrated than ECF
-fluid pulled out
-shrivel
Osmolarity
-measure tonicity
-depends on pH and temp
Total Osmolarity calculation
= Osmolarity of IV + Osmo of added electrolytes
IV infusions of hypo or hypertonic solutions
-hemolysis of RBCs
-renal failure
-death
Example
-calc osmolarity of 1L of 0.45% NaCl (154mOsm/L) with 20mEqKCl (2mOsm/mEq)
-154 + (2*20) = 194 mOsm/L
Calc MIVF
-Holliday-Segar equation (peds or obese)
-just use the clinical estimate is 30-40mL/kg/day
What is a patient’s MIVF needs?
-30-40mL/kg/day
-use actual weight
Example MIVF calc
-(30-40mL/kg) * 91kg = 2730-3640mL/day
-divide by 24 for hourly rate
Maintenance IV Fluids
-MIVF
-normal amt needed over 24 hours