Clotting & Tourniquets

Question 1

How does blood clot?

Answer 1

• Hole in vein
• Platelets sticky and clump around
• Activated platelets and injured tissue produce chemicals that react with clotting factors in blood (I - XIII)
• CFI (fibrinogen) > fibrin (solid protein) traps platelets and blood cells > clot/plug
• May take hours so remind patient not to do anything after that may interfere with it

Question 2

What factors may interfere with the clotting process?

Answer 2

• Abnormal liver function (liver produces CFs)
• Vit K levels (CFII, VII, IX & X depend on)
• Clotting disorders e.g. haemophilia
• Anticoagulants e.g. warfarin, aspirin, heparin
• Hypercoaguability drugs
• Low platelet counts e.g. in immunosuppression, leukaemia, platelet function disorders
• Heavy lifting/excessive movement after

Question 3

What is the general rule for taking blood glucose samples?

Answer 3

They should be taken last in order of draw because bottles contain an enzyme which may adversely affect other tests if cross-contamination

Question 4

What factors may affect the sample quality?

Answer 4

Age
Gender
Race
Pregnancy
Blood taker competence

Question 5

What is haemolysis?

Answer 5

RBC damage, contents leak into blood plasma, so may give false high readings of e.g. K (because most K intracellular. K imp for muscle contraction esp. heart, so quickly rest patients with high K level)

Question 6

Where should tourniquets be ideally positioned?

Answer 6

10cm (hand width) above intended puncture site

Question 7

When should the tourniquet be loosened/removed?

Answer 7

When first tube starts to fill, and never left on longer than necessary

Question 8

What should be removed first, tourniquet or needle?

Answer 8

Tourniquet

Question 9

What is the disadvantage of using a disposable tourniquet?

Answer 9

No slow release mechanism, so no way to easily retighten if blood flow stops. If non-disposable one used, consider washing after each session