Blåt fag Modul 1 Flashcards
What is Heparin and where is it found in the body
Heparin is a fast acting anticoagulant drug.
It is found in mastcells in the lungs, liver and connecting tissue around the blood vessels.
What is heparin derrived from
It is derrived from either bovine or porcine lung and gut tissue
How does heparin work?
Heparin activates AT3, which inhibits thrombin activity.
What is the half life of heparin
1-2.5 hours
Where is heparin Metabolised
Mostly in the liver, and a little by kidneys
If the patient has a decreased liver function, how will that affect the metabolism of heparin
It will decrease the clearence of heparin. Half time is prolonged.
How much affect does heparin have on AT3?
It affects the activation of AT3 by 1000 fold
When is heparin used
It is used pre-bypass (by the anesthesiologist), in the priming solution, and during CPB
How much heparin is given pre-bypass
300-400 IE/kg
What should the ACT be, before going on by-pass?
480
How much heparin should be given in the priming solution (according to the recommendations)
5000 IE/L
What other tests can be used to monitor coagulation
- POC (hemocron jnr.)
- Hepcon - (Protamine titration assay)
- Heptem - (Heparin effects on the hemostasis)
- TT - Thrombin time
- APTT - APTT can not be used when there are high levels of heparin in the plasma
Can you go on by-pass without heparin
No! Because the oxygenator and pump will clot.
Can you cannulate without heparin
No, heparin needs to be given before, otherwise the coagulationsystem is activated.
What is protamin?
Protamin inhibits heparin
How does protamin work
Protamin binds to heparin, making it release AT3
How long is the half life of protamin
About 5min
How much protamin is used to reverse the effects of heparin
2mg/kg
What allergy is important to know before giving protamin
If the patient has a fish or shellfish allergy, because protamin is derrived from fish (salmon) semen.
What happens in an allergic reaction to protamin
You will get an anaphylactic reaction
- Pulmonary hypertension
- Oedema
- Systemic hypotension
- Vascular restriction
Who is most prone to get an allergic reaction from protamin
people with prior protamin exposure and people with fish/shellfish allergies
How is an allergic reaction by protamim treated?
Stop giving protamin!
- 100% O2
- Fluids
- Steroids
- Antihistamines
- vasodialators
- Bronchodialators
When is protamin given
Post by-pass, by the anaestethic team
When test dosis is given, you turn of the last suctions.
How is the effect of protamin measured
By returning the ACT or APTT to the pre by-pass baseline
Can you go back on by-pass after protamin is given
Yes, but a new full dose of heparin must be given, and the ACT is at the required limit according to guidelines
What happens if protamin enters the CPB circuit
It will clot rapidly.. Or not at all. It is very dangerous.
Mention other coagulation disturbances
- Cold agglutinins
- Haemophilia
- DIC (dissiminated intravscular coagulation)
- HIT (Heparin induced thrombopeni)
How do you keep fluid and electrolyte homeostasis in CPB (3)
- Restricting hemodilution
- Minimizing the circuit (shorten tubes)
- Use VAVD
What scenarios makes the perfusionist “mess up” the homeostasis
- Hypovolemia (lack of volume)
- Poor venous drainage
- Blood loss
- Hemodilution
- External suctions or cellsaver
What is homeostasis
It is where the body is in a balanced state internally
Where are possible placements of venous catheters
- single stage in the right atrium (atrial)
- Two stage in the vena cava (cavoatrial)
- Bi caval with 2 single two stages
- In the femoral or iliac vein.
What size are cannulas and catheters given in
In outer diameter!
Does a high pressure drop create greater or lower resistance to flow? (delta P)
A high pressure drop means a smaller inner diameter and therefore equals a greater resistance to flow
What determines pressure drop
Pressure drop is the difference between the fluid entering the cannula and the fluid leaving the cannula.
What different types of drainage are there
- Syphon - Gravity
- KAVD - Kinetic assisted venous drainage
- VAVD - Vaccum
How low should the venous reservoir be placed under heart lvl in cm?
around 40-70 cm