RBC Disorders

Polycythemia

• INC’d Hct - can be >70%

• Occurs w/ cyanotic Congenital Heart Dz’s

Why is Polycythemia concerning?

• ↑ viscosity can impair flow & induce consumptive coagulopathies

• Treat w/ HEMODILUTION

Methemoglobinemia (definition)

• the presence of a higher than normal level of methemoglobin (metHb): >1%

• metHB is an oxidized form of Hgb that has no affinity for O2

MetHgb characteristics

• Inherited or acquired

• Acquired thru the use of nitrates (nitroglycerine)

MetHgb effects

• Results in tissue hypoxia

• Blood will appear Chocolate brown

• Providing normal O2 but pt is cyanotic

MetHgb Treatment

• Methylene Blue 1-3 mg/kg slowly over 5 min

• High doses of Methylene blue can actually cause MetHgb

  • >7mg/kg

Methylene Blue purpose

• Restores iron in Hgb to its normal O2-carrying state

• Should be an immediate response

What to do if Methylene Blue is not successful?

• High dose Vit C

• Exchange Transfusions

If MetHgb is occurring on CPB what should you do?

• 100% O2

• High Flows

Thalassemia (definition)

Inherited, autosomal, recessive blood disorder characterized by insufficient Hgb synthesis

Thalassemia characteristics (RBCs are:)

• Microcytic - abnormally small RBCs

• Hypochromic - RBCs are paler than normal

• Short-lived (~16 days)

• Pt’s often require exchange transfusions

Types of Thalassemia

• Thalassemia Major (Cooley’s Anemia)

• Thalassemia Minor

Thalassemia Major (Cooley’s Anemia) characteristics

• Diagnosed early in life

• Infant anemic/failure to thrive

• RBCs are destroyed at an excessive rate

• Transfusions required

• Iron from breakdown of cells is deposited in many organs causing dmg

Thalassemia Minor Characteristics

• Mild anemia & slight RBC changes

• Do well on CPB

• Treat anemia w/ RBCs if necesary

Elliptocytosis (definition)

A large number of elliptical (oval) shaped RBCs

Elliptocytosis characteristics

• Inherited

• Usually <15% RBCs are affected

• Predisposes pt to hemolytic anemia

Spherocytosis (definition)

The presence of abnormal spherical RBCs

Spherocytosis characteristics

• Inherited

• RBCs are fragile & short-lived (hemolysis & anemia)

• Often require blood transfusion

• May require splenectomy (d/t iron deposits)

Hemosiderosis (definition)

INC’d deposits of iron in some tissues (& waste products of RBCs)

Hemosiderosis characteristics

• Inherited

• Require frequent phlebotomy (regular blood removal to ↓ iron deposits)

• Often found in pt’s w/ various RBC destructive disorders such as thalassemia

Hemochromatosis (definition)

• Causes the body to absorb & store too much iron

• Iron deposits are built up w/in the total body & produce an iron level greater than 15 g

Hemochromatosis characteristics

• Inherited

• Palpable liver, bronze discoloration of skin

• DM & Cardiopathy in 50% of pt’s

• Requires frequent phlebotomy (regular blood removal to ↓ iron deposits)

Erythroblastosis Fetalis characteristics

• Hemolytic Dz of the newborn d/t Rh incompatibility w/ mother

• Alloimmune condition

• occurs when the IgG molecules produced by the mother pass thru the placenta & attach RBCs

Erythroblastosis Fetalis MOA (mother is Rh (-))

1. 1st pregnancy w/ Rh (+) fetus - unaffected

2. in b/w pregnancies mother develops anti-Rh (+) antibodies

3. 2nd pregnancy, if fetus is Rh (+): antibodies will cross the placenta & attack the RBCs

Can be fatal

Erythroblastosis Fetalis treatment

Give RhoGAM

Von Willebrand’s Disease (definition)

• Most common hereditary coagulation abnormality

• A qualitative or quantitative deficiency of von Willebrand’s Factor (vWF)

  • carries Factor VIII

Type I vWD

mild DEC in vWF

Type II vWD

• qualitative vWF defect

• w/ normal levels

Type III vWD

• Most severe

• Homozygous form

• very low levels of vWF

CPB considerations/Treatment for vWD

• Give cryoprecipitate (~10 units)

• Give Desmopressin (DDAVP) w/ bypass termination

  • Helps bring out Factor VIII

Factor V Leiden characteristics

• Inherited hypercoagulable (thrombophilia) disorder caused by a variant clotting Factor V

• Pt’s often present w/ DVT or PE

• Both heterozygous & homozygous pt’s can be affected

  • ↑ risk for homozygous

Hemophilia A

• Most common form of hemophilia (80%)

• Inherited blood clotting disorder characterized by a reduction in the amount or activity of Factor VIII

Treatment for Hemophilia A

• NovoSeven

• Synthetic Factor VIII

• aPTT is a good screening test

Hemophilia B characteristics

• Inherited blood clotting disorder characterized by a deficiency of Factor IX (Christmas Factor)

• Treatment - Give Factor IX

• aPTT is a good screening test

Tool to differentiate Hemophilia A & B

• “A, B”

• “8, 9”

Disseminated Intravascular Coagulation (DIC) (definition)

• Acquired Consumptive Coagulopathy

• Characterized by the formation of small blood clots inside the blood vessels throughout the body

• Lots of clotting occurs & at the same time lots of bleeding d/t ↓ levels of clotting factors (widespread, uncontrollable bleeding)

DIC effects

• Results in low Fibrinogen levels

• Can be detected by Fibrinogen assay

• Can be caused by long pump runs

DIC Treatment

• Treat the underlying cause

• Transfuse platelets, FFP, cryoprecipitate or PRBCs

• Poor prognosis

Vitamin K Dependent Deficiency

• Bleeding disorder

• Inherited or acquired

• DEC’d Factors II, VII, IX, X

• These factors rely on Vit K for their production in the liver

Primary Fibrinolysis (definition)

The body’s continuous process of dissolving fibrin to breakdown small fibrous clots becomes activated in the general circulation

Primary Fibrinolysis characteristics

• Widespread hemorrhage occurs as the fibrinogen becomes depleted

• Can be precipitated by surgery & CPB

Primary Fibrinolysis Treatment

Give Amicar (antifibrinolytic)

Cold Agglutinins (definition)

• Autoimmune Disease

• High conc’s of circulating antibodies that cause agglutination at low temps

IgM interacts w/ RBCs causing

• Hemagglutination

• Microvascular Thrombosis

• Hemolysis (d/t antibody binding)

Hemagglutination

Agglutination of RBCs can occur, leading to impaired BF & tissue oxygenation

Microvascular Thrombosis

Cold agglutinins may cause small blood clots, affecting microcirculation

Pre-op Screening for cold agglutinins

• Determine the titer - temp at which blood will agglutinate

• Consider pheresis or exchange transfusions before surgery

Clinically significant Cold Agglutins

• High titer

• High thermal amplitude

• Positive at 4°C

Clinically insignificant Cold Agglutins

•  Low titer

• Low thermal amplitude

• Negative at 4°C

Management of Non- clinically significant Cold Agglutinins on CPB

• A pt with low titer, low thermal amplitude and asymptomatic can tolerate moderate hypothermic CPB with little risk

• Postpone surgery if possible

• Consider steroid treatment

• know titer temp & consider warm CPG/crystalloid soln

Management of Clinically Significant Cold Agglutinins on CPB

• Maintain normothermia or mild hypothermia above thermal amplitude

• Use warm CPG

If you want to use cold CPG w/ a Clinically Significant Cold Agglutinins on CPB

1. Wash out myocardium w/ initial dose of Warm CPG

2. then give Cold Crystalloid

3. Before removing XC, wash out myocardium w/ Warm Crystalloid

4. Use a sump to drain CPG return from RA until sinus is clear

5. Beware of non-coronary collateral flow

What if we don’t know about cold agglutinins ahead of time?

• Agglutination will generally occur in CPG tubing when you shuttle blood over to the system & cool it

• Subsequent agglutination may be seen systemically

  • High pressure across oxy when cooling

If cold agglutination happens on CPB

1. Rewarm the pt

2. Flush out heart w/ warm soln

3. Subsequent doses of warm blood or warm crystalloid

Thrombocytopenia

Low platelet count

Heparin Induced Thrombocytopenia (HIT)

• Acquired

• caused by the formation of antibodies that activate platelets when exposed to heparin

• IgG bind platelet factor IV & heparin resulting in low platelet count as well as causing the blood to clot

What should we use instead of Heparin in HIT pt’s

• Direct Thrombin Inhibitors (DTIs)

  • Bivalirudin is most common

  • Argatroban w/ renal dysfunction pt’s

• Prostacyclin - anesthetizes platelets

Idiopathic Thrombocytopenic Purpura (ITP)

A condition of having a low platelet count of no known cause

HIT I characteristics

• Non-immune mediated

• More common

• Day 1-4 of initiating Heparin

• Mild symptoms

• No complications

• Can still use Heparin

HIT II characteristics

• Immune antibody mediated

• less common

• Day 4-16 of initiating heparin

• Moderate to severe symptoms

• Life-threatening thromboembolism complications

• Use anticoagulation other than heparin