Difference between revisions of "Haemorrhage"
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==Introduction== | ==Introduction== | ||
* Haemorrhage is the escape of blood from within the cardiovascular system. | * Haemorrhage is the escape of blood from within the cardiovascular system. | ||
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** Neoplastic disease. | ** Neoplastic disease. | ||
* "Haemorrhagic diathesis" describes a predisposition to bleeding, either spontaneous or associated with trifling mechanical damage. | * "Haemorrhagic diathesis" describes a predisposition to bleeding, either spontaneous or associated with trifling mechanical damage. | ||
− | ** Often manifests as [[Haemorrhage | + | ** Often manifests as [[Haemorrhage#Purpura|purpuric disease]]. |
− | ** Haemorrhagic diatheses and [[Haemorrhage | + | ** Haemorrhagic diatheses and [[Haemorrhage#Purpura|purpura]] may be a feature of a number of diseases of different aetiology (poisoning, septicaemia or neoplastic disease). |
==Types of Haemorrhage== | ==Types of Haemorrhage== | ||
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* Two main types of haemorrhage are recognised and are considered in more detail below: | * Two main types of haemorrhage are recognised and are considered in more detail below: | ||
− | ** '''[[Haemorrhage | + | ** '''[[Haemorrhage#Haemorrhage by Rhexis|Rhexis]]''' |
*** Actual physical rupture of a vessel wall | *** Actual physical rupture of a vessel wall | ||
− | ** '''[[Haemorrhage | + | ** '''[[Haemorrhage#Haemorrhage by Diapedesis|Diapedesis]]''' |
*** The escape of blood from vessels. | *** The escape of blood from vessels. | ||
*** It may be difficult to detect a disruption to the vessel wall. | *** It may be difficult to detect a disruption to the vessel wall. | ||
===Haematoma=== | ===Haematoma=== | ||
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* A large blood clot within the tissues. | * A large blood clot within the tissues. | ||
** A localised collection of blood confined by surrounding tissues resulting in a modular formation. | ** A localised collection of blood confined by surrounding tissues resulting in a modular formation. | ||
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===In Body Cavities=== | ===In Body Cavities=== | ||
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* Haemothorax, Haemopericardium and Haemoperitoneum. | * Haemothorax, Haemopericardium and Haemoperitoneum. | ||
** Blood escapes into the respective body cavities. | ** Blood escapes into the respective body cavities. | ||
===Petechiae=== | ===Petechiae=== | ||
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* These are minute - foci are 1-2mm in diameter. | * These are minute - foci are 1-2mm in diameter. | ||
* Of capillary origin. | * Of capillary origin. | ||
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===Ecchymoses=== | ===Ecchymoses=== | ||
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* Of capillary origin. . | * Of capillary origin. . | ||
* Foci are 3-23mm in diameter. | * Foci are 3-23mm in diameter. | ||
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===Purpura=== | ===Purpura=== | ||
− | + | * [[Purpura haemorrhagica|Purpura]] is a clinical syndrome. | |
− | * Purpura is a clinical syndrome. | ||
* Multiple small spontaneous haemorrhages develop in tissues (e.g. skin, mucosae, serosal surfaces and joints). | * Multiple small spontaneous haemorrhages develop in tissues (e.g. skin, mucosae, serosal surfaces and joints). | ||
* A mixture of petechiae and ecchymoses. | * A mixture of petechiae and ecchymoses. | ||
==Haemorrhage by Rhexis== | ==Haemorrhage by Rhexis== | ||
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* This is of venular or arteriolar (or larger vessel) origin. | * This is of venular or arteriolar (or larger vessel) origin. | ||
** Results in major bleeding. | ** Results in major bleeding. | ||
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==Haemorrhage by Diapedesis== | ==Haemorrhage by Diapedesis== | ||
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===Septicaemia=== | ===Septicaemia=== | ||
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* Causes large numbers of petechiae and ecchymoses. | * Causes large numbers of petechiae and ecchymoses. | ||
===Toxaemia and Poisoning=== | ===Toxaemia and Poisoning=== | ||
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* Causes petechiae and ecchymoses. | * Causes petechiae and ecchymoses. | ||
** These haemorrhages are probably due to direct damage to the vessel walls. | ** These haemorrhages are probably due to direct damage to the vessel walls. | ||
===Purpura haemorrhagica=== | ===Purpura haemorrhagica=== | ||
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* Pupura haemorrhagica is a condition that occurs in horses after an infection. | * Pupura haemorrhagica is a condition that occurs in horses after an infection. | ||
** Particularly following [[Respiratory Bacterial Infections - Pathology#Strangles|Strangles]]. | ** Particularly following [[Respiratory Bacterial Infections - Pathology#Strangles|Strangles]]. | ||
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===Haemophilia=== | ===Haemophilia=== | ||
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* Failure of the normal clotting of the blood. | * Failure of the normal clotting of the blood. | ||
** Due to absence of one of the clotting factors. | ** Due to absence of one of the clotting factors. | ||
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===Dicoumeral poisoning=== | ===Dicoumeral poisoning=== | ||
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* Dicoumeral is an antagonist to Vitamin K. | * Dicoumeral is an antagonist to Vitamin K. | ||
** Vitamin K is needed by the liver to synthesise prothrombin and various clotting factors. | ** Vitamin K is needed by the liver to synthesise prothrombin and various clotting factors. | ||
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==Gross Appearance of Haemorrhage== | ==Gross Appearance of Haemorrhage== | ||
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* The gross appearance of haemorrhage can vary depending on the tissue in which it occurs. | * The gross appearance of haemorrhage can vary depending on the tissue in which it occurs. | ||
===Epistaxis=== | ===Epistaxis=== | ||
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* Epistaxis is a nose bleed. | * Epistaxis is a nose bleed. | ||
* The haemorrhage may originate anywhere in the respiratory system. | * The haemorrhage may originate anywhere in the respiratory system. | ||
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===Gastric Haemorrhage=== | ===Gastric Haemorrhage=== | ||
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* Gastric secretion soon turns the blood a dark brown. | * Gastric secretion soon turns the blood a dark brown. | ||
* When vomited up it is called Haematomesis. | * When vomited up it is called Haematomesis. | ||
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===Dysentery=== | ===Dysentery=== | ||
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* Occurs when the bleeding is low down the [[Alimentary System Overview - Anatomy & Physiology|alimentary tract]]. | * Occurs when the bleeding is low down the [[Alimentary System Overview - Anatomy & Physiology|alimentary tract]]. | ||
* The blood is passed in the faeces relatively unchanged. | * The blood is passed in the faeces relatively unchanged. | ||
===Haematuria=== | ===Haematuria=== | ||
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* Blood is present in the urine. | * Blood is present in the urine. | ||
** Imparts a red colour to it. | ** Imparts a red colour to it. | ||
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===Bruising=== | ===Bruising=== | ||
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* Brusing is the result of haemorrhage. | * Brusing is the result of haemorrhage. | ||
* Appears red for 48 hours and then begins to turn yellow. | * Appears red for 48 hours and then begins to turn yellow. | ||
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==Effects of Haemorrhage== | ==Effects of Haemorrhage== | ||
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===Local=== | ===Local=== | ||
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* Haemorrhage may result in a diffuse mass of red blood cells and fibrin in loose connective tissues and in organs. | * Haemorrhage may result in a diffuse mass of red blood cells and fibrin in loose connective tissues and in organs. | ||
** E.g. in the cutaneous connective tissues, the [[Spleen - Anatomy & Physiology|spleen]] and the gut wall. | ** E.g. in the cutaneous connective tissues, the [[Spleen - Anatomy & Physiology|spleen]] and the gut wall. | ||
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===Systematic=== | ===Systematic=== | ||
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* The systematic effects of haemorrhage are usually associated with uncontrolled blood loss. | * The systematic effects of haemorrhage are usually associated with uncontrolled blood loss. | ||
** I.e. from a major artery associated with trauma. | ** I.e. from a major artery associated with trauma. | ||
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** Loss of 30-40 per cent in a few minutes is often fatal. | ** Loss of 30-40 per cent in a few minutes is often fatal. | ||
** Loss of over 50% over a 24 period may be tolerated in the dog. | ** Loss of over 50% over a 24 period may be tolerated in the dog. | ||
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+ | [[Category:Circulatory Disorders - Pathology]] | ||
+ | [[Category:Cardiology Section]] |
Latest revision as of 15:38, 15 October 2013
Introduction
- Haemorrhage is the escape of blood from within the cardiovascular system.
- Can be distinguished microscopically from congestion.
- Congestion - the blood remains within the vessels.
- Haemorrhage - blood is seen outside the vessels.
- Haemorrhage may be of capillary, venous, arterial and rarely cardiac origin.
- May be external or internal (within body cavities).
- Associated with:
- Wounds or trauma.
- Inflammation, where toxins are involved.
- Neoplastic disease.
- "Haemorrhagic diathesis" describes a predisposition to bleeding, either spontaneous or associated with trifling mechanical damage.
- Often manifests as purpuric disease.
- Haemorrhagic diatheses and purpura may be a feature of a number of diseases of different aetiology (poisoning, septicaemia or neoplastic disease).
Types of Haemorrhage
- Two main types of haemorrhage are recognised and are considered in more detail below:
- Rhexis
- Actual physical rupture of a vessel wall
- Diapedesis
- The escape of blood from vessels.
- It may be difficult to detect a disruption to the vessel wall.
- Rhexis
Haematoma
- A large blood clot within the tissues.
- A localised collection of blood confined by surrounding tissues resulting in a modular formation.
- Often sub-cutaneous.
- May form space-occupying lesions.
- E.g. in brain.
In Body Cavities
- Haemothorax, Haemopericardium and Haemoperitoneum.
- Blood escapes into the respective body cavities.
Petechiae
- These are minute - foci are 1-2mm in diameter.
- Of capillary origin.
- Usually seen on the skin, mucous membranes and serosal surfaces.
Ecchymoses
- Of capillary origin. .
- Foci are 3-23mm in diameter.
- Are blotchy.
- Often confluent.
- Usually seen on the skin, mucous membranes and serosal surfaces.
Purpura
- Purpura is a clinical syndrome.
- Multiple small spontaneous haemorrhages develop in tissues (e.g. skin, mucosae, serosal surfaces and joints).
- A mixture of petechiae and ecchymoses.
Haemorrhage by Rhexis
- This is of venular or arteriolar (or larger vessel) origin.
- Results in major bleeding.
- There are several causes of haemorrhage by rhexis.
- Trauma.
- Haemorrhagic enteritis.
- Erosion of blood vessels by tumours or abscesses.
- Idiopathic rupture of arteries.
- In the horse intrapericardial rupture of the aorta may occur, although this is uncommon.
Haemorrhage by Diapedesis
Septicaemia
- Causes large numbers of petechiae and ecchymoses.
Toxaemia and Poisoning
- Causes petechiae and ecchymoses.
- These haemorrhages are probably due to direct damage to the vessel walls.
Purpura haemorrhagica
- Pupura haemorrhagica is a condition that occurs in horses after an infection.
- Particularly following Strangles.
- Endothelial damage is caused by accumulation of immune complexes.
Haemophilia
- Failure of the normal clotting of the blood.
- Due to absence of one of the clotting factors.
- Rare.
- Reported in dogs and pigs.
Dicoumeral poisoning
- Dicoumeral is an antagonist to Vitamin K.
- Vitamin K is needed by the liver to synthesise prothrombin and various clotting factors.
- Occurs with:
- Warfarin poisoning
- Warfarin is a common rat poison)
- Prolonged feeding of sweet clover.
- Warfarin poisoning
Gross Appearance of Haemorrhage
- The gross appearance of haemorrhage can vary depending on the tissue in which it occurs.
Epistaxis
- Epistaxis is a nose bleed.
- The haemorrhage may originate anywhere in the respiratory system.
- Can occur in the lungs following heavy exercise in the horse.
- Appears bright red and perhaps frothy.
Gastric Haemorrhage
- Gastric secretion soon turns the blood a dark brown.
- When vomited up it is called Haematomesis.
- Blood originating in the stomach and upper small intestine that is passed through the anus and is called Melena.
Dysentery
- Occurs when the bleeding is low down the alimentary tract.
- The blood is passed in the faeces relatively unchanged.
Haematuria
- Blood is present in the urine.
- Imparts a red colour to it.
- It is important to distinguish this from haemoglobinuria.
- In haemoglobinuria, the breakdown products of red blood cells appear in the urine following intravascular haemolysis.
- In haemorrhage, the red blood cells will separate out and sediment to the bottom of a test tube.
Bruising
- Brusing is the result of haemorrhage.
- Appears red for 48 hours and then begins to turn yellow.
- Due to macrophages converting haemoglobin into haemosiderin.
Effects of Haemorrhage
Local
- Haemorrhage may result in a diffuse mass of red blood cells and fibrin in loose connective tissues and in organs.
- E.g. in the cutaneous connective tissues, the spleen and the gut wall.
- Alternatively, a local accumulation may form a haematoma and become a space- occupying lesion.
- This may interfere with organ function.
- E.g in intracranial haemorrhage, haemopericardium, and pulmonary haemorrhage.
- This may interfere with organ function.
Systematic
- The systematic effects of haemorrhage are usually associated with uncontrolled blood loss.
- I.e. from a major artery associated with trauma.
- Rate of loss is critical, e.g.
- Loss of 30-40 per cent in a few minutes is often fatal.
- Loss of over 50% over a 24 period may be tolerated in the dog.