Fluids and Blood Flashcards
What two compartment make up the ECV?
ECV = 34% of TBW, 2-% body mass
- Plasma volume
- Interstitial volume
How do you estimate fluid deficit?
4-2-1 rule
1-10kg = 4ml/kg/hr
11-20 = 40 + 2ml/kg/hr
Each kg >20kg = 60 + 1ml/kg/hr
Fever - for each degree >37, add 2.5ml/kg for every 24 hours
List 4 signs of hypovolemia
- dry mucous membranes
- dec sensorium
- dec UOP
- dec or variable BP with position and PPV
What 3 things most commonly cause fluid loss during surgery?
- Evaporation
- Internal redistribution
- Blood loss
What is the ratio of blood loss to crystalloid replacement?
1L blood : 1.3-1.6L crystalloid
What are the contents in Normal Saline?
pH 5.0
Osmolality 308
Na 154
Cl 154
What are the contents in LR?
pH 6.5 Osmolality 275 Na 130 Cl 109 K 4 Ca 3 Lactate 28
What are the contents in Plasmalyte?
pH 7.4 Osmolality 294 Na 140 Cl 98 K 5 Mg 3
What are some side effects from using Hetastarch?
anticoagulant effects >20 mL/kg/day or 1L
decreased function of:
factor VIII
von Willebrand factor
fibrinogen
PRURITIS
Increased M&M in critically ill patients
What evidence is there about relative benefits and risks of crystalloid vs. colloid resuscitation?
SAFE study
No significant differences were found with respect to mortality
Albumin & hetastarch were found to be associated with higher mortality in patients with traumatic brain injury
What are some side effects from using Dextran?
decreasing platelet aggregation
prolonged bleed time
allergic reactions
Crystalloid solution associated with hyperchloremic metabolic acidosis in volumes >3L
NS
How much should transfusion of one unit of PRBCs increase [Hbg], in the absence of continued bleeding?
1g/dL
Describe the components of a unit of PRBCs
180 ml of RBCs
30 ml of citrate-phosphate-dextrose (CPD) anticoagulant preservative.
30 ml of plasma
Describe the symptoms of acute hemolytic reaction
awake patient - pain at the infusion site, dyspnea, chest pain, flank pain and rigors
anesthetized patient - red urine, hypotension, fever, and coagulopathy
- STOP transfusion
What is the starting dose for transfusion of FFP? What is the goal of FFP transfusion?
10-15 mL/kg, with the goal of achieving 30% of clotting factor concentration
What are the components of FFP?
250ml of volume
ALL plasma proteins and clotting factors
= not a concentrate of any of the clotting factors = should NOT be used to treat specific deficiencies (hemophilia) unless factor concentrates are not available
How is FFP stored and how long is its shelf life?
FFP is frozen at -18 to -30°C within 8 hours of collection
Gently thawed in water bath –> used within 6 hours
Used up to 1 year after collection
What are some indications for use of FFP?
- Rapid and emergent reversal of warfarin (one could also use Factor VIIa or various available concentrates of Factors II, VII, IX, and X).
- Correction of factor deficiencies in the absence of available factor concentrates.
- Correction of AT-III deficiency for patients receiving heparin (often in the setting of cardiac or vascular surgery, but a specific concentrate is also available).
- Correction of non-surgical (microvascular) bleeding in patients who have been transfused more than one blood volume.
- Correction of microvascular bleeding in patients with abnormal coagulation parameters. This applies to a PT more than 1.5 times normal, an aPTT more than 2 times normal, and an INR more than 2.0.
What are the implications of platelet storage temperature?
must be stored at room temperature = higher risk of transmitting infection and a shorter shelf life
What is the most common reason anesthesiologists transfuse cryoprecipitate?
microvascular bleeding + fibrinogen level
What is currently the best reason to administer dextrans?
plastic or vascular surgery to improve perfusion and decrease the risk of thrombosis
Where does cryoprecipitate come from and what are its contents?
FFP is thawed at 4°C, a precipitate remains, which can be separated by centrifugation = cryoprecipitate
Factor VIII Factor XIII von Willebrand factor Fibrinogen Fibronectin
Is ABO compatibility necessary for:
- Platelets?
- FFP?
- No - but incompatible –> shorter half-life
2. Yes
What changes occur during PRBC storage?
pH drops potassium increases calcium and magnesium decrease (citrate binds them) factors V and VIII degrade PRBCs lyse
Why is clinically significant hyperkalemia after massive transfusion unlikely in patients with normal renal function?
K = 19-30 mEq/L after 21 days of storage due to leakage from PRBCs as well as PRBC lysis –> hyperkalemia during massive transfusion at rates of >120 ml/min
What is the preferred test to follow calcium levels during and after massive transfusion?
Ionized Ca
Total serum calcium will measure citrate-bound calcium + free calcium in the ionized form and may not accurately reflect free serum calcium
Why is metabolic alkalosis more commonly induced by massive transfusion rather than metabolic acidosis?
citrate in stored blood is metabolized to bicarbonate by the liver via the Krebs cycle
low pH of citrate-containing storage solutions + erythrocyte metabolism forming lactic acid and pyretic acid –> pH 6.5 after 35 days of storage
storage containers impermeable to CO2 –> to pCO2 levels of 150-200 mmHg.
Acidosis in the setting of hemorrhage is more likely due to hypo perfusion –> anaerobic metabolism in peripheral tissues and consequent accumulation of lactic acid
What are the manifestations of citrate toxicity?
signs and symptoms of HYPOCALCEMIA: *hypotension* narrow pulse pressure increased intraventricular end-diastolic pressure prolonged QT interval
What factors can lead to accumulation of citrate?
Poor liver function –> slow metabolism by liver
Hypothermia –> dec metabolism
Name 5 factors that contribute to coagulopathy during massive transfusion.
hypothermia tissue injury acidosis duration of shock DIC
What is the generally accepted platelet level below which clinically significant surgical bleeding is more likely?
50,000
How does massive transfusion inhibit proper function of clotting factors?
deficiency of most clotting factors, especially factors V and VIII and fibrinogen
probably occurs as a result of dilution
Describe how hypothermia contributes to bleeding in the setting of massive transfusion.
non-functional enzyme clotting factors
Lethal Triad
- hypothermia
- coagulopathy
- acidosis
What is the shelf life of appropriately harvested and preserved red blood cells?
Whole blood and RBC components in storage solutions such as CPDA-1 (citrate, phosphate, dextrose, adenine) = 35-42 days at 2-6 degrees C
Rare RBC blood types may be frozen in glycerol and stored for up to ten years