Chapter 18: Surgical Hemostasis

Question 1

How long can the abdominal aorta be ligated for?

Answer 1

30 mins

Question 2

How long can the Portal triad (Pringle) be ligated for?

Answer 2

10-15 mins

Question 3

How long can the Hepatic artery be ligated for?

Answer 3

30 mins

Question 4

How long can the splenic artery and vein be ligated for?

Answer 4

15-20 mins

Question 5

How long can the renal artery and vein be ligated for?

Answer 5

30 mins

Question 6

Tourniquets over what pressure can cause demyelination?

Answer 6

> 1000mmHg - causing compression of nerves causing neurological deficits for up to 6 months postop

Question 7

Tourniquet max time is?

Answer 7

1.5 - 2 hours due to ATP depletion

Question 8

Two recommendations for applying a touniquet?

Answer 8

Use the widest one you can
Elevate the limb before application to help exsanguinate leg.

Question 9

Exsanguination of the limb prior to tourniquet or with Esmarch is not recommended in what 2 circumstances?

Answer 9

Infection and/or neoplasia

Question 10

What can reduce the risk of ischemic damage when using a tourniquet?

Answer 10

hypothermia

Question 11

What are the three groups of hemostatic agents?

Answer 11

Mechanical agents, active agents and hemostatic sealants

Question 12

What are possible complications of hemostatic agents?

Answer 12

volumetric swelling
exothermic reaction
foreign body reaction
inhibition of normal tissue healing
immunogenic reaction

Question 13

When should hemostatic agents not be used?

Answer 13

in intravascular spaces
when blood salvage procedures are being used (autotransfusion - can get through the 40um filters)

Question 14

How do mechanical hemostatic agents work?

Answer 14

Swell in response to bleeding and can be a matrix for clot to form on - rely on normal clotting

Question 15

Do mechanical hemostatic agents inhibit healing?

Answer 15

They inhibit the healing of tissue edges of skin

Question 16

Gelatin combined with what is more effective than gelatin on its own?

Answer 16

Thrombin

Question 17

Which one collagen or gelatin actively promotes platelet aggregation?

Answer 17

Collagen
gelatin does not

Question 18

How does gelatin reabsorb?

Answer 18

Via granulomatous inflammation with ingrowth of fibroblasts developing rapidly following placement of the sponge

Question 19

How long in experimental studies do gelatin sponges take to absorb?

Answer 19

5 weeks

Question 20

How can you tell if a gelatin sponge is what you see on advanced imaging or if it is a tumor?

Answer 20

Small little pockets of air in the foam

Question 21

Bovine collagen is what type of collagen? How long does it stay there and how is it removed?

Answer 21

Type 2
8-10 weeks and is absorbed by fibroblast remodeling

Question 22

what is the name of the cellulose used as a hemostatic agent?

Answer 22

Oxidised regenerative cellulose (ORC)
- unknown mechanism
- appears to form a large gelatinous clot
- works independently from coagulation pathway
- acidic properties may cause denaturing of blood proteins

Question 23

Why might cellulose be a less effective hemostatic agent than others?

Answer 23

The acidic environment inactivates thrombin

Question 24

Is cellulose bactericidal?

Answer 24

Yes
Against Gram - and Gram + aerobes and anaerobes

Question 25

How long does resorption of cellulose take?

Answer 25

2-6 weeks

Question 26

Name 3 mechanical hemostatic agents that are not gelatin/collagen or cellulose?

Answer 26

bone wax ostene polysaccharide spheres - dehydrate the blood

Question 27

Alginates cannot be used in which environments and why?

Answer 27

In body cavities - they cause foreign body reactions

Question 28

How does thrombin work?

Answer 28

Actively converts fibrinogen in blood to fibrin to create a clot (It's Factor II)

Question 29

Fibrin is what type of hemostatic agent?

Answer 29

Active - works independently from the patients own clotting pathway - derived from pooled human plasma

Question 30

What is a concern with synthetic sealants? How long to absorb?

Answer 30

They swell up to 400% - need to be used with caution next to vital structures 4-8 weeks

Question 31

Antifibrinolytics are either lysine (EACA, tranexamic acid) or serine (aprotinin) protease inhibitors - which one is more potent and why?

Answer 31

Lysine is more potent as it binds more strongly to the plasminogen molecule

Question 32

How does tranexamic acid work?

Answer 32

thrombin time prolonged and stabilizes clot - does not affect platelet number or normal coagulation times

Question 33

Desmopressin is what? how does it work?

Answer 33

A synthetic analogue of arginine vasopressin that stimulates the release of factor 8 and vWF from endothelial cells

Question 34

What are the main side effects of desmopressin?

Answer 34

antidiuretic effect causing hyponatremia and water retention

Question 35

Ethamsylate improves what?

Answer 35

platelet adhesiveness and aggregation in the presence of vascular injury - Also anti-inflammatory and improves blood flow in necrotizing pancreatitis

Question 36

What is chitosan?

Answer 36

A natural biodegradable non toxic carbohydrate derived from deacetylated chitin from shrimp shells - it rapidly forms a gel-like clot on contact with blood