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Pathology of Shock In Organs, image …
Pathology of Shock In Organs
What happens when the Heart undergoes Ischaemic Changes and then Low Flow Infarcts ?
Heart
Initially, the heart will undergo fatty change.
As the shock progresses, individual myocytes start to die and contract forming Contraction Band Necrosis.
If untreated the area furthest away from the blood supply will start to die, Sub-endocardium.
Sub-endocardium dies , this is visible microscopically as Subendocardial Haemorrhage/Infarct.
Transmural infarct if pre-existing atherosclerosis.
What happens when the Lungs undergoes Initial and then Progressive Shock ?
Diffuse Alveolar Damage
There will be diffuse damage to the alveolar lining epithelium and capillaries.
This increases the permeability. Causing fibrin and fluid to exude into the alveolar spaces.
Fluid accumulation causes acute pulmonary oedema and respiratory stress (Acute Respiratory Distress syndrome)
Fibrin exudate deposits into the alveolar spaces, forming hyaline membranes.
If a patient survives, the fibrinous exudate become organized and thick fibrotic alveolar septae form (diffuse pulmonary fibrosis)
What happens when the Liver undergoes Initial and then Progressive Shock ?
The centre of the lobule is distal to portal supply.
The Liver will undergo Centrilobular Haemorrhagic Necrosis aka Shock Liver
When the Liver is shocked the Centre of the Lobule will undergo centrilobular congestion, stasis and hypoxia, fatty change and eventually Centrilobular Haemorrhagic Necrosis.
Peripheral Lobules can show fatty change.
What happens when the Stomach undergoes Ischaemia ?
When the stomach undergoes Ischaemia there is a decrease in the mucosal defenses against HCL acid secreted by the stomach.
Mucosa will develop Haemorrhages that progress to Acute peptic Ulcer.
Cushing Ulcer (Stress)
Curling Ulcer (Burns)
Perforation
This is known as Ischaemic Gastroenteropathy
Kidney
What Happens to A Kidney when it undergoes Ischaemia ?
Oliguria or Acute Renal Failure
ATN: Necrosis of the PCTs, due to selective vulnerability.
ACN or BCN (Bilateral Cortical Necrosis): Necrosis of the Glomerulus and other tubules due to severe shock.
Papillary Necrosis
Colon
What happens when the Colon undergoes Initial and then Progressive Shock ?
The colon will develop Mucosal Haemorrhages and Watershed Infarct at the:
Junction between the Superior and Inferior Mesenteric Artery
And the Junction between the Inferior Mesenteric Artery and Hypogastric Artery.
It can Perforate as well.
Pancreases
What Happens when the Pancreas undergoes Ischaemia ?
When the pancreases undergoes Ischaemia, the cell injury results in the release of Zymogens.
Zymogens become activated into Digestive enzymes: Lipase, Elastase and Protease which digest Fats, Vessel, Pancreatic Acini causing Fat Necrosis, vasculitis and Pancreatitis.
This is known as Acute Pancreatitis Haemorrhages
Brain
What happens to a Brain when is undergoes Ischaemia and then Low Flow Infarcts ?
The Brain will undergo:
Selective Neuronal Necrosis
Watershed Infarcts
Cortical Laminar Necrosis
Hypoxic ischaemic Encephalopathy
Watershed Infarcts
Watershed infarcts are also known as Boundary Zone Infarcts.
Watershed infarcts are Bilateral.
They are found between the:
Anterior and Middle Cerebral Arteries
Middle and Posterior Cerebral Arteries
The Anterior and Middle Cerebral Arteries are most affected by Hypoperfusion.
When these zones undergo necrosis, a sickle-shaped band of necrosis will occur.
This is because the border between the arterial territories have a sickle shaped appearance.
Cortical Laminar Necrosis
Cortical Laminar Necrosis is band-like necrosis in the cortex due to the vulnerability of neuron in cortical layer 3 to hypoxia.
Hypoxic Ischaemic Encephalopathy (HIE)
Global Brain Hypoxia can occur in:
Birth Asphyxia (Cerebral palsy), Cardiac Arrest
Widespread Hypoxia and Hypoglycemia.
Neuronal Injury due to toxins and free radical resulting in cerebral Oedema.
Fatal if not severe brain death.
Pituitary Gland
What happens when the Pituitary Gland Undergoes Shock ?
Pituitary Gland is prone to necrosis in shock
The Anterior Pituitary is most vulnerable as it is the 2nd capillary bed.
Hypothalamus is the 1st capillary bed.
Anterior Pituitary Gland is prone to infarction in Post-Partum Haemorrhage because the Pituitary Gland expands during pregnancy to cater for additional demands of the foetus.
Pituitary Gland is located in the part of the skull known as the Sella Turcica
When the necrotic pituitary gland finally disappears it leaves behind an empty Sella Turcica
Simmonds Syndrome is the general term given to Pan-hypopituitarism due to pituitary gland destruction
Sheehan Syndrome is the term used in Obstetric context. (Post partum)
NOTE: panhypopituitarism: GSH¯ (dwarfism in children), FSH¯, LH¯ (amenorrhoea),
ACTH¯ (Addison disease), TSH¯ (hypothyroidism), ADH¯ (diabetes insipidus)
What happens to Adrenal Glands when they undergo Ischaemia and Low Flow Infarcts ?
DIC in the adrenal glands causes Adrenal Gland Failure and/or Bilateral Adrenal haemorrhage
When the adrenal gland can no longer produce adrenalin, patient develops profound shock.
The syndrome of adrenal insufficiency secondary to adrenal haemorrhage is called Waterhouse-Friderichsen Syndrome
It is Associated with DIC (Skin Purpura) and Septic Shock and Meningoccaemia
How to treat shock and DIC
Treat the cause Anti-histamine for anaphylaxis, stop bleeding
Treat the underlying mechanism: vasopressors for distributive shock, fresh frozen plasma for DIC
Prevent/Treat Complication: Proton-pump inhibitors, ventilators, dialysis, inotropes
Stress Ulcers are the dark spots that are less that 1 cm in diameter, and have a dark brown base. with a distinct margin.
Stress Ulcers develop in all regions of the stomach.
Acute Haemorrhagic Pancreatitis with Fat Necrosis
