Week 9 - Clotting and Coagulation Flashcards
What is the best way to determine surgical bleeding risk?
Thorough history and physical –> During interview may aid in a decision to get labs drawn to if indicated
What things may patients complain about with undiagnosed coagulopathies during the interview?
Frequent hematomas, runaway bruising, and oozing after minor injuries
What are some physical signs of bleeding that warrants further investigation?
Bruising or petechial hemorrhages on chest, abdomen, or upper extremities
Where is vitamin K created?
Bacteria from the gut
What factors does vitamin K form?
Factors 2, 7, 9, 10, proteins C and S
What patient problems may be present in patients who are unable to form or use clotting factors?
LIVER DISEASES
What 2 things are important to ask the patient when assessing anticoagulant drugs they are taking?
What drug they are taking and when they took the last dose
How does Aspirin work?
Irreversibly inhibits cyclooxygenase which inhibits formation of prostaglandins and in turn Thromboxane A2 –> decreases function of the platelet
Patients should stop taking aspirin _____________ days prior to surgery
7-10 days
NSAIDS need to be withheld ______________ hours prior to surgery, why?
24-48 hours. These drugs reversibly block cyclooxygenase which prevents prostaglandin from forming, preventing the synthesis of thromboxane A2, so only a day or two is needed for platelets to regain function
Which herbal supplements can cause increased bleeding time?
All herbal supplements on table
What is a normal bleeding time?
3 - 7 minutes –> Qualitative assessment platelet count and function!
When can cryoprecipitate be given due to low fibrinogen levels?
80-100 mg / dL or less
What is a normal ACT?
80 - 150 seconds
What must the anesthesia provider do in an emergent or trauma situations that require surgery in regard to blood coagulation?
Must rely on on information supplied by family members, physical, and lab testing
Should coagulation labs be ordered on every patient prior to surgery?
No, only if indicated through doing a thorough history and physical
What can be done in a situation where a patient requires surgery, but not emergently. The patient presents with an elevated PT time
Administer vitamin K 4-6 hours prior to surgery for reversal –> 10-20 mg IM
If bleeding risk is moderate, what should be done prior to surgery? A type and crossmatch OR a type and screen?
Type and crossmatch
What should be done in an emergent surgery when the patient could be at an increased risk for bleeding?
Ordering all the blood components to have access to in the OR –> PRBCs, FFP, Platelets, and cryoprecipitate
What is the purpose of thromboxane A2 in the clotting process? What medications prevent this from occuring?
Constrict the vessel so vWF and platelets can adhere to the site of injury –> NSAIDS reversibly block this and ASA agents irreversibly block this
Prolonged bleeding will occur resulting in inadequate hemostasis
If a patient has a prolonged bleeding time, but hasn’t taken any medications that would cause this, what would be suspected? Should the case be cancelled?
Primary hemostasis abnormality –> Further investigation should be done
Just because a patient has a prolonged bleeding time DOES NOT mean they are at increased risk of bleeding or that an abnormality is present.
Is an isolated, slightly elevated bleeding time reason enough to cancel or delay a surgery?
No
Does a patient with a normal platelet count mean they have normal platelet function
No, only a representation of the quantity of platelets in the plasma with no correlation to function of the platelets
When is a patient considered throbocytopenic?
Counts less than 100,000
The patients platelet count drops below 50,000? What should be suspected?
You should suspect the patient will have prolonged bleeding under surgical conditions.
What platelet count is minimum for adequate hemostasis?
Greater than 100,000
When is a platelet count considered at a critical level? What can occur?
Less than 20,000. Spontaneous bleeding can occur
What does a PT time evaluate?
PET –> All extrinsic pathways and common pathways (3, 7, 10, 5, 1, and 2)
Most commonly used test to monitor oral anticoagulant therapy (Coumadin derivatives –> Warfarin)
Prolonged in deficiencies in these factors or warfarin.
What are some drawbacks to a PT test?
Not very sensitive. Does NOT tell you which clotting factor is deficient or what the issue is. Only which pathways (extrinsic and common)
What is considered mild thrombocytopenia?
50,000 - 100,000
How is a PT test preformed?
Patient plasma is incubated with source of tissue factor
What does a PTT test measure?
Intrinsic and common pathway deficiencies or heparin therapy (12, 11, 9, 8, 10, 5, 2, 1, and ultimately 13) –> Also screens for acquired coagulation inhibitors like factor 8 antibodies and lupus anticoagulants
What factor would be missing in hemophiliacs?
Hemophilia A (Factor 8) and Hemophilia B (Factor 9)
Does a prolonged PTT always indicate a bleeding disorder?
No
What would be suspected if both a PT and PTT time were elevated?
Typically a common pathway deficiency –> Liver disease or DIC
What must occur within the body before a patient presenting with a prolonged PT or PTT time?
Factor that is deficient must be decreased by 30%
What factor deficiency won’t cause increased bleeding? Which ones will?
Factor 12 WILL NOT, Factors 9 and 8 WILL
What does an activated clotting time test?
Quick test used in surgery to monitor the ability of blood to clot –> Normal is 90 - 150 seconds
Most commonly used to guide anticoagulant dosing
What does thrombin time assess?
The ending phase of coagulation
What three things does a thromboelastogram (TEG) measure?
- Platelet reactions
- Coagulation
- Fibrinolysis
What does a normal TEG look like?
What would a hemophiliacs TEG look like?
How do you interpret a TEG?
What factor is approved for use in hemophilia A, B, factor 7 deficient, and universal hemostatic agent by the FDA?
Factor 7 –> VERY expensive
