test 4 Flashcards
What is a significant predictor of mortality in cardiac surgery
- RBC transfusion
AABB recommends
- looking at symptoms rather than just the hgb number
Transfusion risks: Infectious
◦ Bacterial
◦ Hepatitis
◦ HIV
Transfusion risks: Non Infectious - Febrile Reactions
Fever, chills
Pt antibodies are reacting with white cell antigens or white cell fragments in the transfused blood products.
-OR- due to cytokines which accumulate during storage.
Most common with platelet transfusions
Transfusion risks: Non Infectious - Uticarial (Allergic) Reactions
- rash
1% of population
Urticaria, puritis, flushing
Caused by foreign proteins
Transfusion risks: Non Infectious - Anaphylactic Reactions
Hypotension, tachycardia, cardiac arrhythmia, shock, cardiac arrest
caused by patients who have IgA deficiency who have anti-IgA antibodies.
Require special washed/ tested blood products
Transfusion risks: Non Infectious - Acute Hemolytic Reactions
Caused by transfusion of ABO incompatible blood
Chills, fever, pain, hypotension, dark urine, uncontrolled bleeding due to DIC
Transfusion risks: Non Infectious - Volume Overload
- not seen on bypass
Transfusion risks: Non Infectious - Hypothermia
- not seen on bypass
Caused by transfusion of too many cold blood products
Transfusion risks: Non Infectious - Citrate Toxicity
Metabolized by liver
Rapid transfusion of large quantity of blood products
Binds calcium and magnesium – depleting stores
Myocardial depression
Coagulopathy
- combat by giving Ca2+
Transfusion risks: Non Infectious - Potassium Effects
Stored RBC leak K+
Irradiation increased the rate of leak
Cardiac effects
- combat by washing the cells or Z-buff
Transfusion Related Acute Lung Injury (TRALI)
◦ Symptoms: Similar to ARDS (Acute respiratory distress syndrome)
Hypotension, Fever, Dyspnea, Tachycardia
◦ Non-Cardiogenic pulmonary edema with diffuse bilateral pulmonary infiltrates on CXR (chest xray)
◦ Occurs within 6 hours of tx
Most cases present w/in 1-2 hours
◦ All blood products are culprits
◦ Occurs 1/2000 transfusions
Transfusion Related Acute Lung Injury (TRALI) Pathophysiology
Pathophysiology: Unclear.
◦ Attributed to HLA Antibodies, Granulocyte antibodies and biologically active mediators in the blood.
Treatment: Ventilator support for ~96 hours
Mortality: 5-10%
Transfusions associated with:
◦ Longer hospital stays
◦ Longer time to extubation
◦ Morbidity
◦ Mortality
Techniques to help minimize our impact on blood usage?
◦ Autologous transfusion ◦ Pre-bypass autologous donation ◦ Intraoperative Cell Saver use ◦ Shed mediastinal blood recovery ◦ Accept lower hematocrit ◦ Retrograde Autologous Priming ◦ Hemoconcentration ◦ Plasma/Platelet Pheresis ◦ Mini-circuits
Blood conservation techniques (2)
Bloodless Medicine
Blood Conservation
What is Bloodless Medicine
◦ MULTIMODALITY and MULTIDISCIPLINARY approach to patient care without the use of allogenic blood.
AKA: Transfusion-Free Medicine
- USE EVERYTHING IN YOUR POWER TO NOT GIVE TRANSFUSION
What is Blood Conservation
◦ Global concept aimed at REDUCING (doesn’t exclude the use) patient exposure
to allogenic blood products. Does not exclude use.
History of giving blood
Bloodless medicine used to be associated with Jehovah’s Witnesses
Jehovah’s Witnesses refrain from accepting blood products due to religious beliefs
Now Bloodless Medicine is used b/c studies have shown better patient outcomes
History of giving blood with Jehovah’s Witnesses
Jehovah’s Witnesses decision to refuse blood was religious, but they used scientific information regarding the side effects.
A Booklet Blood, Medicine, and the law of God (1961) addressed the issues related to tx:
◦ Transfusion reactions
◦ Transfusion related syphilis, malaria, hepatitis
1960’s
1960’s – Not easy to refuse blood on religious grounds
◦ Frequently obtained court orders to give blood
JW Representatives started meeting with doctors to explain why transfusions were refused
◦ Offered literature with techniques JWs accepted
◦ “Transfusion alternatives”
- it must be one continuous circuit and needs to be primed
Denton Cooley (Early 1960’s)
Published article in the American Journal of Cardiology (1964) titled Open heart surgery in the Jehovah’s Witness”
Described his techniques for treating these patients
1977 – reported experience with 500 JW patients
Adoption of bloodless surgery spread worldwide
Not a particular technique, but the spirit and attitude toward the approach
Military and blood management
Did surgery on wounded soldiers before transfusions were even available
Confronted with blood loss, but no way to replace the blood
◦ Stopped the hemorrhage promptly and effectively
◦ Avoid further blood loss
Surgical skill is a major factor in need of blood!!
World War I
◦ Blood Anticoagulation
Allowed for transport of blood to the wounded
PROBLEM: Storage!
World War II
◦ Storage problem overcome with the advent of blood banks
Military and blood management: 1953
Use of blood alternatives
◦ Switched from plasma to Dextran (volume expander)
Sugar substrate
Due to incidence of hepatitis transmittal
Military and blood management: 1985
Started looking into “blood substitutes”
◦ Searched for oxygen carrier
Military and blood management: Introduction of Cell Savers
◦ Surgeon Gerald Klebanoff (Vietnam Vet) introduced the first cell saver in a military hospital.
Military and blood management: Recombinant Factor VIIa
◦ Hemopheliacs
◦ Israeli army discovered potential to stop life threatening hemorrhage
What you need for a bloodless management program
Hospital Commitment
- EVERYONE (Administration, Physicians, Nurses, etc.)
Coordinator to recruit physicians dedicated to the mission in a variety of specialties
What can be done pre-op: Obtain a focused history
◦ Age – tolerance of anemia is age dependent
Elderly don’t tolerate
As age increases, risk of transfusion increases
◦ Gender – women are more likely than men to get transfused
Lower hct and prone to blood loss with menses
◦ Weight/Height – required to do calculations
Small patients and obese patients are at risk for transfusion
Race/ Ethnicity/ Background/ Religion
Anemia and Coagulation disorders are associated with certain races
What can be done pre-op: Ask about patient-related obstacles to transfusion-free therapy
◦ Anemia ◦ Hemostatic disturbances ◦ Medical conditions increasing perioperative blood loss ◦ Obstacles to surgical hemostasis ◦ Factors decreasing anemia tolerance
What can be done pre-op: Lab work
◦ Hgb
◦ PT/INR / PTT
◦ Platelet Count and Platelet Function Tests
What can be done pre-op: Treat any anemia
◦ Optimize Hgb prior to surgery
What can be done pre-op: Treat Polycythemia (increased number of red blood cells in the blood)
◦ Risk of hemorrhage during surgery (hyperviscosity)
◦ Plebotomy
What can be done pre-op: Avoid pharmacological coagulopathies
◦ Drugs (not anticoagulants) that have increased bleeding risk
What can be done pre-op?
Obtain a focused history Ask about patient-related obstacles to transfusion-free therapy Lab work Treat any coagulopathies Treat any anemia Treat Polycythemia Avoid pharmacological coagulopathies
Anesthesia resource to help blood management
Help correct any coagulopathies/anemia preop.
Help position the patient to decrease blood loss
Provide controlled hypotension
Keeping patient warm
◦ Optimizes clotting
Choice of Drugs
Timing of fluid administration
◦ Restrict until surgical hemostasis is achieved
Intravascular pressure is not too high
Autologous Donation
◦ Donation where the donor and recipient are identical
Patient donates blood to be used on themselves during surgery.
Avoids use/ risks of donor blood
May not be practical or cost effective for most cardiac surgeries
Requires a hematocrit of 33%
Donation of whole blood can be split
◦ Allows not only donation of RBC, but also FFP
◦ Requires special order from physician
Plateletpheresis and Plasmapheresis
◦ Allows the donation of platelets and plasma
Autologous Donation Contraindications
◦ Recent MI ◦ CHF ◦ Aortic Stenosis ◦ Transient Ischemic Attacks ◦ Hypertension ◦ Unstable Angina ◦ Bacteremia
Prebypass autologous normovolemic hemodilution
- donate to yourself but do not change your volume by adding crystalloid
Spares platelets from bypass
◦ Retain/ preserve function
Requires a hct of 35%
Remove about 500-1000mL (1-3 units)
◦ Depends on starting hct
◦ Depends on age of patient
◦ Depends on BSA
◦ Depends on coexisting conditions
Blood is placed in a bag with anticoagulant
◦ Usually CPD (citrate-phosphate-dextrose)
Reinfused after protamine is administered
Prebypass autologous normovolemic hemodilution Contraindications
◦ COPD ◦ CHF ◦ CAD (CABG) ◦ Unstable Angina ◦ Renal Insufficiency ◦ Severe Aortic Stenosis ◦ Coagulopathy
Retrograde autologous priming (RAP)
Performed prior to bypass
Arterial and venous cannula are in place
Use the patient’s blood pressure to displace prime.
Remove prime via:
◦ Stopcock on ALF
◦ Arterial sampling manifold
◦ Y’s in circuit
Can be done quickly
Must closely watch patient’s pressures
◦ Remove about 200-600mL of Prime
Dry venous Line
Requires the use of VAVD
Venous line is emptied prior to connection to
the venous cannula
Volume is removed to a bag and discarded or
sequestered
Eliminates about 400-1000mL
Cautions:
◦ Only works if patient has adequate volume pre-op
◦ If patient is dry (not a lot of volume), will need the volume anyways
Mini-circuits
AKA: Miniaturized Extracorporeal Circuits
Decreases foreign surface area
Decreases prime volume
Decreases blood-air contact
Attempt to:
◦ Decrease hemodilution
◦ Decrees inflammatory response
◦ Decrease volume shiftsWhat are mini-circuits
Closed A-V Loop with centrifugal pump, membrane oxygenator, coated tubing
◦ No venous reservoir
◦ No cardiotomy
◦ Often no heat exchanger or arterial line filter
◦ Centrifugal pump provides kinetic assisted venous drainage and blood flow
Prime volume is about 500mL
◦ Can be decreased with RAPing
Used mostly for CABGs
◦ Some valves have been done
Types of Mini-circuits (2)
◦ Totally Integrated Devices
Include air handling and elimination systems, centrifugal pump and membrane oxygenator.
◦ Combination of components
Benefits of Mini-circuits
◦ Less inflammatory reaction
◦ Less activation of coagulation and fibrinolysis
◦ Less hemodilution
◦ Less use of autologous blood
◦ Marginally improved renal and neurological function
Results in the studies are mixed
Concerns of Mini-circuits
◦ Air handling
◦ Requires surgeon to take care to avoid air entrapment around the cannula
◦ More microemboli with MECCs compared to normal circuits
◦ No reservoir = no way to handle excess volume
◦ No immediate volume infusion
◦ No heat exchanger (on most)
◦ Use of separate cell saver (Delay in processing, loss of factors/platelets)
◦ Increased cost
◦ Adaptability when surgical complications/ need requires normal ECC
Ways of making our regular circuits mini without using a mini-circuit
Cut lines short
Get as close to the table as possible
Elevate the reservoir
◦ Use VAVD
Put modular pump heads near outlet/inlet of oxygenator
Dry venous line
◦ Requires VAVD
Go on with low prime volumeUltrafiltration / Hemoconcentration
Filtration of water across a semipermeable membrane via hydrostatic pressure gradient
Water crosses the membrane which creates a solute concentration gradient
Solutes have a higher concentration in blood so they move to the water side which has a lower solute concentration
So, we’re removing “water”
And electrolytes
Modified Ultrafiltration (MUF)
Withdrawing blood from the patient via the arterial line (post bypass)
Running the blood through a hemoconcentrator
Pumping the blood back into the patient via the venous line.
Can use the cardioplegia circuit
◦ Make sure to flush out the cardioplegia solution with blood
◦ Pump flow rate less than MUF flow rate
Cell Salvage intraoperative
Use heparinized saline or CPD as an anticoagulant
Cells are separated from the fluid by a centrifuge
◦ RBC fall to the bottom, Plasma on top
RBC washed with 3x bowl volume (min)
Put in a reinfusion bag for administration
Removes: Fat, air, tissue debris, potassium, hormones, bioactivators, etc.
Limitations of cell salvage
◦ Delay in processing ◦ Loss of plasma proteins ◦ Loss of coagulation factors and platelets ◦ Expense ◦ Operator attention and time
Reinfusion of shed blood
Blood collected from the mediastinum and pleural cavities post op can be reinfused
◦ Doesn’t clot due to defibrination
◦ Increased level of free Hgb
◦ Contains activated products
***NOT ideal
◦ Used in urgent situations
◦ Can be processed
Cardiopat
Shed blood can be collected and processed by a cell processing device – Cardiopat
Uses a dynamic disk to process.
◦ Processes a variable volume of blood
Consistently delivers washed RBCs w/ hct of 70-80%
Processes up to 2 liters per hour or as little as 5 mL of RBCs
ACCEPTANCE OF LOWER HEMATOCRIT
Acceptable level varies by institution
Healthy, Good LV Function
◦ Tolerate 20-25%
Those with limited coronary flow, increased metabolic needs, respiratory issues will require increased hematocrits
Overall conclusion for blood conservations
Blood conservation is a team approach
Everyone involved in each step of a patient’s care need to be on board
◦ Primary care physicians, nurses, surgeons, anesthesiologists, perfusionists, residents/ fellows
◦ One player not on board can significantly alter the course of that patient’s care.
