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 grav
- BUN/Creat
Why are maintenance fluids given?
To replace insensible losses
- from respiritory tract, GI tract, urine, feces, perspiration, etc
What is the formula for maintenance fluids?
4-2-1 Rule!
- 4cc/kg for the 1st 10 kg
- 2cc/kg for the 2nd 10 kg
- 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!
- Inpatient - may not have a fluid deficit if on maintinence fluids
- Also, if hypovolemic at baseline, they will have a larger than calculated fluid deficit.
- ex- on ACE inhibitors, have been vomiting, have NG to suction, chest tube, etc.
- 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 3rd 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
100-150 cc (soaked an dripping)
We tend to (over/under)estimate the amount of blood loss
Underestimate
Calculations for estimated blood volume (EBV)
Neonates
- Preemies = 95 mL/kg
- Term = 85mL/kg
- Infants = 80 mL/kg
- Children = 70 mL/kg
Adults
- Men = 75 mL/kg
- Women = 65 mL/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 (0-2 mL/kg/hr)
- Eye cases, lap chole, hernia, knee scope
-
Moderate (3-5 mL/kg/hr)
- Open chole, appendectomy
-
Severe (6-9 mL/kg/hr)
- Bowel surgery, total hip replacement (THR)
- Emergency (10-15 mL/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
- LR
- Plasmalyte
- Normosol
Examples of hypertonic solutions and their osmolarities
- Used for hyponatremia or shock
- D51/2NS (432)
- 3% NS (1026)
- Do NOT use for fluid resussitiatin
- Risk hyperchloremia, hypernatremia, cellular dehydration
Advantages and disadvantages of crystalloids
Advantages:
- Easily warmed and stored
- non-allergenic
Disadvantages:
- 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+
LR
- the most physiologic crystalloid solution most similar to ECF
- Should NOT be given with blood products d/t Ca++
- Provice <strong>100</strong> <strong>cc</strong> of <strong>free water/L</strong> (which is lower sodium)
It is made of normal saline with additives:
- 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) → BUFFER! → will be converted to bicarbonate
- pH = 6.5
Normal Saline
- 0.9% NaCl in water
- Isotonic solution
- In large volumes increase Cl-→ dilutional hyperchloremic acidosis
- Prefered solution for diluting PRBCs → No K or Ca
Electrolytes:
- Na+ (154 mEq/L)
- Cl- (154 mEq/L)
- pH = 6.0
Normosol
- Exactly physiologic pH
- Can give with blood products
It is made of normal saline with additives:
- Na+ (140 mEq)
- K+ (5 mEq/L) → avoid in hemodialysis pts!!
- Ca++ (0 mEq/L)
- Cl- (98 mEq/L)
- pH = 7.4
- Magnesuium (3 mEq/L)
- Acetate (27 mEq/L)
- Guconate (23 mEq/L)
This can result from large volumes of .9%NS
High chloride-content hyperchloremic acidosis
This is the preferred solution for diluting PRBCs
Normal Saline
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
- Is also used as a carrier for regular insulin
- Provides 170 - 200 calories / liter
- Used in neonates too
Half-life of colloid solutions
16 hours (but may be as short as 2-3 hours)
Benefits of colloids
- Easy to store
- inexpensive
- less risk of edema
- safer to give than blood (no viral transmission, etc.)
Albumin is available in these concentrations
5% or 25%
We use 5% in the OR
What is IV albumin?
It’s obtained from fractionated human plasma, however, does not contain antibodies or coagulation factors
What is dextran made of?
Water-soluble glucose polymers that are enzymatically degraded to glucose.
Two types of dextran and what they’re used for
- Dextran 40 - used on the pump for thrombosis prevention
- Dextran 70 - used for volume expansion***
SE of dextran
- Anaphylaxis (1 : 3,000 pts)
- Platelet inhibition (causes increased bleeding. Max dose of 20mL/kg in 24 hours)
- Noncardiac pulmonary edema (from volume expansion)
- Interference with crossmatching
Benefits of hetastarch
It’s as effective as albumin for volume expansion, but less expensive.
How is hetastarch stored and excreted within the body
Stored within the reticuloendothelial system (phagocytic system) for several hours and excreted via the kidneys.
Hetastarch and dextran can both cause bleeding problems, but differ in how they do it. What is the MOA for this in each and what is the max dose for each?
Dextran → plt inhibition
Hetastarch→ dilutional thrombocytopenis
Max dose for both is 20mL/kg.
In renal failure, which should dextran or hetastarch be chosen?
- Dextran** This is enzymatically degraded into glucose.
- Hetastarch, however, is exreted via the kidneys.
Intravascular half-life for crystalloids
20-30 min
(colloids have half-life of 2-16 hours)
This type of fluid is preferred in hypoproteinemia
Colloids
What is the only reason to transfuse blood?
To increase O2 carrying capacity
Transfusions are rarely indicated if Hgb > ____ and are almost always indicated if Hgb
- 10
- 6
- Transfusion between this range is based on the pt’s risk for complications and inadequate oxygenation
What is cell saver?
- Recovering blood lost during surgery and re-infusing it into the patient.
- It is a major form of autotransfusion.
T or F?
Indications for transfusion are more liberal for autologous blood vs. blood bank blood
True
Risks of blood product administration
- Hep B (1 : 269,000)
- Hep C (1 : 600,000)
- HIV (1 : 1,780,000)
- Bacterial sepsis
- Platelets (apheresis ) - 1 : 50,000
- Platelets (in whole blood) 1 : 33,000
- Platelets (untested) 1 : 2,500-13,400
1 Unit of PRBCs will increase Hgb by
1 gm/dL
What is the Hct of PRBCs
70%
What are PRBCs reconstituted with?
- 0.9% NS
- 5% dextrose in 0.9% NS
- 5% dextrose in 0.4% NS
- Normosol-R (pH of 7.4)
Citrate toxicity and blood transfusions
- Citrate is the anticoagulant used in blood products.
- Massive PRBC transfusion can cause citrate to accumulate.
- Citrate binds to calcium and magnesium
- This causes hypocalcemia and hypomagnesemia.
What is autologous blood transfusion?
- Autologous blood transfusion is the collection of blood from a single patient and retransfusion back to the same patient when required.
- The pt is able to donate a unit of blood (450cc) of blood every few days in the weeks leading up to surgery (up to 4 units).
- The last collection should take place at least 48–72 h before surgery to allow for equilibration of blood volume.
Complications of autologous transfusion
- Anemia (from collections) and resultant myocardial ischemia
- Administration of the wrong unit (1 : 100,000)
- Need for more frequent transfusion
- Febrile and allergic reaction
Uses for platelet transfusion
- Thrombocytopenia
- Dysfinctional platelets
- Active bleeding
- PLT count
One unit of platlets will increase platlet count by:
7,000 - 10,000
Volume given when plts are transfused
200-400 cc
Contamination risk with plts
- Bacterial contamination 1 : 2,000
- Plt related sepsis 1: 12,000 (be wary of this if pt spikes fever within 6 hours of administration)
Volume of FFP given
200-250 cc
Does FFP have to be ABO compatible?
Yes
What is FFP composed of?
- Clotting factors
- plasma proteins
- No Platlets!!
Uses for FFP
Used for coagulation factors
- Emergent reversal of warfarin
- To correct known coagulation factor deficiencies
- To correct microvascular bleeding in the presence of an increased PT or PTT
- To correct microvascular bleeding in someone who has been transfused with more than one blood volume when PT and PTT can’t be obtained in a timely fashion
Each unit of FFP increases each clotting factor by ___%
2-3%
What is FFP NOT used for (contraindicated use)?
NOT used to increase plasma volume or albumin concentration
How is cryoprecipitate made and what does it contain?
- derived from the precipitate remaining after FFP is thawed.
- Contains:
- Factor VIII and XIII
- Fibrinogen
- vWF
Is cryo ABO compatible?
Yes
What is cryo used for?
- von Willenbrand’s disease
- Fibrinogen deficiencies
- usually caused by consumptive coagulopathies or massive hemorrhage
How should cryo be given?
- Rapidly and through a filter (200mL/hr).
- Infusion must be complete within 6 hours.
Are plts given through a warmer or filter?
No
This colloid comes in two forms: 40 and 70
Dextran
Which is more likely to cause pulmonary edema, crystalloids or colloids?
crystalloids it more likely to cause peripheral tissue edema, but less likely to cause PULMONARY edema
Are crystalloids just as effective as colloids in restoring intravascular volume as long as enough is given?
Yes
Which supports UO better, crystalloids or colloids?
Crystalloids
More tissue edema occurs with (crystalloids/colloids)
Crystalloids
Larygospasm is caused by contraction of these muscles
- Lateral cricoarytenoids
- Cricothyroid
- Thyroarytenoid
Components of Normosol -R
- Sodium 140 mEq/L
- Potassium 5 mEq/L
- Calcium 0 mEq/L
- Chloride 98 mEq/L
- Glucose 0 mEq/L
- Magnesium 3 mEq/L
- Acetate 27 mEq/L
- Gluconate mEq/L 294 Osm
- ph 7.4
Calories provided by D5W
- D5W gives 170-200 calories/1000mL
- may cause hyperglycemia
hypertonic solutions risks
- hyperchloremia
- hypernatremia
- cellular dehydration