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
Ideal Fluid
-predictable effects
-inc IV volume
-no accumulation
-cost
-stability
-convenience
Types of Fluids
-Crystalloids
-Colloids
Crystalloid Solutions
-give water and/or sodium
-maintain osmotic gradient
Crystalloid Solutions
-NS
-1/2 NS
-D5W
-LR
-balanced salt solutions
Normal Saline (0.9% NaCl)
-used for IV fluid REPLACEMENT
-RESUSCITATION
-NOT FOR MAINTENANCE
-Na and Cl replacement
1/2 NS (0.45%NaCl)
-used for MAINTENANCE FLUIDS (combo products)
Lacated Ringers
-REPLACE blood loss
-approximates human plasma
-RESUSITATION (trauma/burn)
-better than normal saline
D5W (Dextrose 5%)
-free water replacement
-NOT resuscitative
-NOT and MIVF by self
Balanced Salt Solutions
-Crystalloid solutions w physiologic levels of chloride and buffer solutions
-**
Examples of balanced salt solutions
-Lacated Ringers
-Normosol-R
-Plasma-lyte
-NOT saline
0.9% NaCl composition
-154 mEq/L Na+
-154 mEq/L Cl-
-NO water (100% ECF distribution)
-acidic pH
-10% more sodium and 50% more Cl than normal plasma
0.45% NaCl composition
-half 0.9
-has 500 mL free water tho (2/3 ECF distribution)
Most similar to physiological electrolytes
-Normosol-R
-Plasma-lyte
-also have normal pH
-and buffers
NS complications vs balanced salt solutions
-inc mortality
-inc acidosis
-inc blood transfusions
-inc renal injury
-inc hyperkalemia
-inc postop infection
Generally only use Normal Saline
-when someone is low on sodium
-prefer balance salt solutions (normosol, LR, plasma-lyte)
Colloid Solution MOA
-ALWAYS HYPERTONIC
-inc plasma oncotic pressure
-move fluid from interstitial to plasma compartment
Colloid solution place in therapy
-plasma expanders
-inc molecular weight
-corresponds to increased IV retention time compared to crystalloids
Colloid Solution use
-selective volume expansion or IV repletion in symptomatic pt
-hemorrhagic shock w crystalloid
-second line for hypovolemic shock after crystalloid
Colloid Tonicity
-HYPERtonic
Colloid examples
-Albumin
-Hetastarch
-Tetrastarch
-Blood
-Plasmanate
Albumin
-human derived
-5% or 25%
-supportive/symptomatic treatment unless hypoproteinemia
Albumin indications
-volume expansion
-shock
-burn
-ARDS
-cardiopulmonary bypass
-Intraoperative fluid repletion
Albumin adverse effects
-HYPERvolemia
-Azotemia
-infusion related reaction/anaphylaxis
Albumin 5%
-250-500mL vial
-50mg/mL
-treat HYPOvolemia or intravascular depletion
Albumin 5% dosing
-0.5-1g/kg prn
-2-4mL/min if normal plasma level
-5-10 if hypoproteinemia
Albumin 25%
-50mL or 100mL vial
-250mg/mL
-tx fluid and/or sodium restricted patients
Albumin 25% dosing
-Paracentesis >5L
-5-8 g/L removed (round to nearest 25g)
-1mL/min for normal plasma
-2-3mL/min for hypoproteinemia
Composition of Synthetic Colloids
-substitution ratio (SR)
-Molecular Weight (MW)
-not using these
-black box for sepsis
Substitution Ratio (SR)
-number of hydroxyethyl groups per glucose
High substitution ratio
> 0/5
-leads to prolonged IV expansion
high molecular weight of synthetic colloid
-alters coagulation
>200kDa
High SR and MW
-increase mortality and toxicities
Synthetic colloids
-Hetastarch (Hespan)
-Tetrastarch (Voluven)
-use with caution
Synthetic Colloid safety concerns
-inc mortality at day 90
-risk renal replacement therapy
-inc association with bleeding
Blood (Colloid)
-packed RBCs
-1 unit = 230-350mL
Use of blood
-acute blood loss (30-40%)
-inadequate resuscitation from fluids alone
-preop
-low hemoglobin
Low hemoglobin
< 7-8g/dl
-1 unit RBCs increases hemoglobin by approximately 1g/dL
most common MIVF
-D5W + 1/2NS + 20 mEq KCl/L
-inc plasma oncotic pressure
-similar composition to urine
Monitoring Fluid Status
-daily weight
-daily ins/outs
-volume status (dehydration)
-Urine output in mL/kg/hr
-vitals
Monitoring volume status
-volume overload
-euvolemic
-dehydration
Monitoring vitals
-HR/BP
-Central Venous Pressure (CVP)
-invasive hemodynamic parameters (catheter)
Signs of Dehydration
-decreased skin turgor
-dry membranes
-delayed capillary refill
-maybe TACHYCARDIA and HYPOtension
-peripheral pulses weak
-deacreased urine output/dark urine
-high BUN/SCr ratio
-vary on age, disease, meds, cause of fluid depletion
Low urine output
< 0.5mL/kg/hr
-dehydration
High BUN/Scr ratio
> 20
-dehydration
Distribution percentage of crystalloid fluids at 100% ECF
-0.9% NaCl
-3% NaCl
-LR
-normosol
-Plasma-lyte
-resuscitative
Distribution percentage of crystalloid fluids at 2/3 and 1/3
-0.45% NaCl
-0.225% NaCl
-D5W
-maintenance
Albumin 5% vs 25%
-5% for people that need more fluid
-25% for people that don’t need/cant have more sodium