Lecture 5, hemorrhage and hemostasis Flashcards

1
Q

Hemorrhage

A

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
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2
Q

Arterial hemorrhage

A
  • 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
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3
Q

Venous hemorrhage

A
  • Ruptured vein
  • Rather dark red
  • Steady, profuse bleeding
  • Spontaneous hemostasis possible
  • Level of danger dependant on the diameter of the vessel
  • Potentially life-threatening
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4
Q

Capillary hemorrhage

A
  • 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
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5
Q

Parenchymatous hemorrhage

A
  • 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
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6
Q

Blood volume of body weight

A

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

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7
Q

Classification of hemorrhage, class I

A

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

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8
Q

Classification of hemorrhage, class II

A

Mild blood loss 15-30%

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

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9
Q

Classification of hemorrhage, class III

A

Moderate blood loss 30-40%

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

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10
Q

Classification of hemorrhage, class IV

A

Severe blood loss >40%

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

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11
Q

Blood loss

A

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)

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12
Q

Hemostasis

A

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)
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13
Q

How hemostasis happen?

A
  • 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
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14
Q

Ways to do provisional artificial hemostasis

A

Manual pressure
Tamponade
Pressure bandage
Hemostats (forceps)
Tourniquet

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15
Q

Ways to do definitive hemostasis

A

Mechanical
Physical
Chemical
Biological

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16
Q

Mechanical hemostasis

A

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

17
Q

Physical hemostasis

A
  • Low local temperature – vasoconstriction (minor bleeding)
  • High temperature: electrocautery
  • Monopolar
  • Bipolar
18
Q

Chemical hemostasis

A

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

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

19
Q

Biological hemostasis

A

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)