Fluid Management Flashcards
Between the ISF and the ICF, ____ is the main determinant of extracellular osmotic pressure
Na+
Between the ISF and the ICF, ____ is the main determinant of intracellular osmotic pressure
K+
What is hematocrit?
It is also known as the packed cell value (PVC). It is measured by dividing the volume of RBCs in a centrifuged blood sample by the total volume of the sample.
What are some ways that we can assess fluid volume status?
Vital signs Skin turgor Mucous membranes Edema Lung sounds UO Hct Urine spec gav BUN/Creat
Why are maintenance fluids given?
To replace insensible losses (from resp tract, GI tract, urine, feces, perspiration, etc)
What is the formula for maintenance fluids?
4-2-1 Rule!
4cc/kg for the 1st 10kg
2cc/kg for the 2nd 10kg
1cc/kg for each additional kg
How to calculate fluid deficit
(Maintenance rate) x (number of hours NPO)
But remember to look at pt history! May have been NPO, but was probs receiving IV fluids if pre-admitted to the hospital (no deficit).
Also, if hypovolemic at baseline (ex- on ACE inhibitors, have been vomiting, have NG to suction, chest tube, etc.), they will have a larger than calculated fluid deficit.
Fluid should be replaced to restore HR, BP, and filling pressures prior to induction**
Normal UO is also desirable
Replacement strategy for fluid deficit
Replace over 3 hours
Replace 1/2 deficit in 1st hour
Replace 1/4 in the 2nd hour
Replace final 1/4 in the third hour
When should we begin fluid deficit replacement?
ASAP! Start fluids in the holding area. Want to make sure they aren’t totally dry on induction.
A soaked 4x4 holds _____cc of blood
10cc
A soaked lap sponge (lap tape) holds ___cc of blood
100-150cc (soaked an dripping)
We tend to (over/under)estimate the amount of blood loss
Underestimate
Calculations for estimated blood volume (EBV)
Neonates
Preemies = 95mL/kg
Term = 85mL/kg
Infants = 80mL/kg Children = 70mL/kg
Adults
Men = 75mL/kg
Women = 65mL/kg
Calculating ABL
[EBV (Hct - allowable Hct)] / Hct
Remember that this is not the trigger for transfusion. Always look at your pt’s condition (HR, BP, Sats, etc). You may need to transfuse earlier than expected.
Fluid loss due to third spacing may be caused by
Burns, trauma, infection.
Loss of intravascular volume due to massive redistribution of fluids.
Surgeries and their expected evaporative/3rd space loss
Minimal (0-2mL/kg/hr)
- Eye cases, lap chole, hernia, knee scope
Moderate (3-5mL/kg/hr)
- Open chole, appendectomy
Severe (6-9mL/kg/hr)
- Bowel surgery, total hip replacement (THR)
Emergency (10-15mL/kg/hr)
- Gun shot, MVC
D5W has an osmolarity of
253 (these are called maintenance fluids)
Isotonic solutions have an osmolarity of
300 (these are called replacement fluids)
Examples of isotonic solutions
NS and LR
Examples of hypertonic solutions and their osmolarities
Used for hyponatremia or shock
D51/2NS (432)
3% NS (1026)
Advantages and disadvantages of crystalloids
Adv:
Easily warmed and stored, non-allergenic
Disadv:
No O2 carrying or coagulation capacity, limited intravascular life (will be peed out by patient), more risks of extravasation and edema
LR provides ____cc of free water per liter of fluid
100cc
This tends to lower Na+
This is the most physiologic crystalloid solution (most similar to ECF)
LR
This fluid should not be give with blood
LR –> the calcium can cause the blood to clot
Electrolyte concentrations in LR
Na (130 mEq/–> results in hyponatremia
K (4 mEq/L) –> avoid in hemodialysis pts!!
Ca (2.7 mEq/L)
Cl (110 mEq/L)
Lactate (27 mEq/L) –> will be converted to bicarbonate
This can result from large volumes of .9%NS
High chloride-content hyperchloremic acidosis
This is the preferred solution for diluting PRBCs
NS
D5W can cause these adverse effects
Free water intoxication and hyponatremia
What use does D5W have?
Really only used for diabetics who need just a little more glucose, and is used as a carrier for regular insulin
Half-life of colloid solutions
16 hours (but may be as short as 2-3 hours)