Lecture 5, hemorrhage and hemostasis

Question 1

Hemorrhage

Answer 1

An abnormal escape of blood from an artery, a vein, an arteriole, a venule or a capillary network

• Caused by traumatic injury/medical condition
• External/internal
• Primary hemorrhage occurs soon after an injury
• Secondary hemorrhage follows an injury after a considerable lapse of
  time
• Arterial/venous/capillary/
  parenchymatous

Question 2

Arterial hemorrhage

Answer 2

• Ruptured artery
• Bright red colour (oxygen)
• Flow ordinarily in waves of spurts
• May be steady if artery is deep
• Spontaneous hemostasis rare
• Life-threatening
• Hardest to control

Question 3

Venous hemorrhage

Answer 3

• Ruptured vein
• Rather dark red
• Steady, profuse bleeding
• Spontaneous hemostasis possible
• Level of danger dependant on the diameter of the vessel
• Potentially life-threatening

Question 4

Capillary hemorrhage

Answer 4

• Ruptured capillaries
• Most common
• Mix of arterial and venous blood (fairly bright)
• Trickle of blood (small drops at a time)
• Spontaneous hemostasis likely
• Usually not life-threatening
• Easiest to control

Question 5

Parenchymatous hemorrhage

Answer 5

• Injury to a parenchymal organ (liver, spleen, pancreas etc.), corpus
  cavernosum (penis, clitoris), cancellous bone
• Similar to capillary hemorrhage, bleeding more profuse
• Spontaneous hemostasis unlikely or time-consuming
• Potentially life-threatening

Question 6

Blood volume of body weight

Answer 6

7-9%, in cats ~6,5%

Question 7

Classification of hemorrhage, class I

Answer 7

HR, RR, BP normal, normal urine output, slightly anxious

Question 8

Classification of hemorrhage, class II

Answer 8

Mild blood loss 15-30%

HR↑, RR↑(mild), BP normal, oligouria, confused, irritable, cool extremities

Question 9

Classification of hemorrhage, class III

Answer 9

Moderate blood loss 30-40%

HR↑↑, RR↑, BP↓, oligouria, lethargic, cool extremities

Question 10

Classification of hemorrhage, class IV

Answer 10

Severe blood loss >40%

HR↑↑↑, RR↑↑↑, BP↓↓, anuria; lethargic, comatose; cold extremities, cyanosis

Question 11

Blood loss

Answer 11

Prognosis dependant on many factors (severity, rate, concurrent
disorders)

Medical attention in case:
* Bleeding does not stop
* Class II (recommended), Class III or IV (necessary)

Blood loss → hypovolemic shock →
death (1/2 - 2/3 of total blood volume lost)

Question 12

Hemostasis

Answer 12

Complex process involving platelet activation and circulating clotting
factors. Causes blood from escaping the damaged blood vessel.

The balance of anti- and procoagulants keeps the blood in liquid form.

• Physiological hemostasis
• Artificial hemostasis
• Temporary (provisional)
• Definitive

1. Vascular spasm
2. Platelet plug formation
3. Clot formation (coagulation)

Question 13

How hemostasis happen?

Answer 13

• Injury → vasoconstrictors released from endothelium (endothelin) →
  vasoconstriction at the site → (aggregation and) adhesion of platelets (plug formation)
• Thromboplastin (combination of phospholipids and tissue factor)
  catalyzes the conversion of prothrombin (nonactive) to thrombin →
  thrombin causes fibrinogen to polymerize →
  polymerized fibrin forms
  long strands of tough unsoluble protein that are bound to the
  platelets → formation of a hemostatic clot

Question 14

Ways to do provisional artificial hemostasis

Answer 14

Manual pressure
Tamponade
Pressure bandage
Hemostats (forceps)
Tourniquet

Question 15

Ways to do definitive hemostasis

Answer 15

Mechanical
Physical
Chemical
Biological

Question 16

Mechanical hemostasis

Answer 16

Tamponade –
the closure or a blockade of a wound as if or by a tampon to stop bleeding (absorbent material, pressure); mildcapillary or parenchymatous hemorrhage

Ligation –
placement of a surgical suture (smallest material possible?)
around a vessel; arterial, venous hemorrhage
* Transfixation ligature (larger arteries)
* Mass ligature – preferably not used

Question 17

Physical hemostasis

Answer 17

• Low local temperature – vasoconstriction (minor bleeding)
• High temperature: electrocautery
• Monopolar
• Bipolar

Question 18

Chemical hemostasis

Answer 18

Topical substances
* Bone wax (tamponade)
* Gelatin- and cellulose-based hemostatic products (clotting)
* Adrenalin (vasoconstriction)

Systemic treatment (mostly preventive)
* Ca
* Vitamin K
* Tranexamic acid (Cyclokapron)

Question 19

Biological hemostasis

Answer 19

Goal is to promote coagulation

Localized use:
* Covering the bleeding (not severe) with a part of the omentum

Systemic use:
* Blood transfusion (blood coagulation factor concentrates)