AZ vaccine and clots

 KYJ - knowing your jargon.

How does someone have clots yet no platelets?

Clots and vaccines?? 

Thrombosis with thrombocytopenia??? 

The links between AstraZeneca’s Covid vaccine and this unique thrombotic reaction still have so many unanswered questions, and women under 60 are a little nervous.

Here is some of what we know:

The condition is Thrombosis with thrombocytopenia.   Which, almost seems counterintuitive.   How to I clot without platelets??? 

As always in my posts, let’s go back- 

Some terms:

Thrombocytes are platelets; small cell fragments present in blood and serve to assist in stopping bleeding. They form clots.

Clot : is a clump of platelets packed together like snow flakes in a snowball.

Thrombus is a clot that is strengthened by gumming it together with strands of protein called Fibrin.  

Fibrin is a sticky stringy thread like substance that forms when liquid proteins in the blood called coagulation Factors (specifically Factor X(10), prothrombin and fibrinogen) are activated or triggered in a process called Coagulation.

So recap:   To clog up a blood vessel that is injured and bleeding, we form a clot and strengthen it with coagulation.

Together this makes a stable clot.   That is called a thrombus.

Now Thrombocytopenia means a reduced number of platelets.   Normally 150-400 thousand/ micro-litre of blood.

So technically a platelet count below 150 is regarded as Thrombocytopenia.

Recognise that clotting (involving platelets) and coagulation (involving a chemical protein chain reaction), are separate processes that, together, stop bleeding.

The technicality of the marriage between platelets and coagulation is a magnetic attraction.  Romantic I know. 

But platelets have a chemical they release called Platelet factor 4

 PF4 is positively charged.

A natural protein called Heparin circulates in blood preventing those coagulation proteins activating.   That’s why we call heparin a blood thinner- it isn’t, it’s actually a coagulation stopper (anticoagulant).

Heparin is negatively charged.

So.... remember the magnet? 

Negative sticks to positive right?

Well heparin sticks to Platelet Factor 4.

Boom! 

 

Heparin is switched off. Blood in the vicinity of activated platelets starts to form Fibrin which wraps around the clot like a fishnet around a bait ball of prawns, forming the clot into the thrombus.  The change in charge also further activates platelets to activate .

So...

 what triggers the syndrome .

Well we think it’s the immune (inflammatory) reaction where platelets are first triggered to activate and release PF4.

Clots then set off a chain reaction of where clots trigger fibrin formation (coagulation) which in turn, triggers more clots.   As clots form, platelets die off reducing their population to low levels- thrombocytopenia.

It is similar to a rare condition called Heparin induced Thrombocytopenia ( HIT ) .

Like this AZ vaccine stimulus, HIT is also thought to be the result of an immune reaction to complexes formed when negatively charged heparin molecules bind to a positively charged platelet factor 4.

Its like dropping a cigarette butt into a forest of tinder dry leaves, it creates its own microclimate and spreads like wild fire.

The syndrome also has some similarities to the effect of some snake venoms.   Brown snakes particularly - cause both clotting (early); though to be the cause of early snake bite deaths (inside the firs few hours), then,because the platelets are depleted, they start bleeding. It’s called consumptive coagulopathy.

In AstraZeneca vaccine recipients affected by this rare clotting syndrome, the number of platelets crashes.

They had platelets, but they got used up forming clots triggered by the immune response, now leaving thrombi behind in their wake.

It appears within two weeks, usually between day 4 and 20.

The weird thing is these AZ clots tend to form directly in Gut vessels, brain and lungs.

Not in the deep veins which is typical of other thrombosis disorders.

There are so many unanswered questions here.

Why this vaccine and not the others?  Dunno

Why not flu shots and other vaccines ?  Dunno.

Why women > men ? Dunno 

Anyhow I’ve Roberted on for a lot longer than anticipated , so I’ll park it there with a quick plug for my online pathophysiology series 

Called “Physiology with Rob”

There is a live seminar on this stuff in Brissy in Nov if you check out the web page.

Www.ECT4Health.com.au

Geek on all you thrombocytes! 

~Rob

#Knowingyourjargon

#kyj

#ECT4Health

Capillary pressure

 How is a Decubitus Ulcer(bed sore), 

a subdural Haemorrhage, 

a spinal cord injury,

And glaucoma all similar?

They are obviously different, but the one pathophysiology they have at there core, is pressure.

Let’s talk capillary pressure

Capillary pressure (Pc) is the pressure difference across the interface between two immiscible (un-mixable)fluids arising from the capillary forces.

 At the end of your arteries the arterial blood supplying oxygen and nutrient to ALL tissues enters the smallest of blood vessels- the capillaries.

A single cell thick and full of tiny holes called fenistrations, capilliaries are the end of blood’s journey to perfuse tissues.

(More on capilliaries in my video  here : https://youtu.be/sdWhUmUuWqc )

Unlike the high pulsing pressure in arteries, capillary pressure, ranges from 10 to 22 mmHg , and here is the crux.

If external or internal compartment pressures from compression, oedema or other internal or external forces exceed these forces, then the tiny capilliaries are squished (real word), and oxygen doesn’t reach its destination tissue/organ.

Now think the patient lying on their buttocks, or heels lying in one place on the bed. There is too much compression over these bony prominence, this exceeds the capillaries pressure, the tissue becomes ischaemic (lacking oxygen), and ultimately tissue dies. This is exactly how Pressure ulcers start.

In closed head Injury, then maybe collections of blood (haematoma), and as the tissues of the brain start to become inflamed and swell, along with the collection of haematoma, intracranial pressure rises. When the rise in  intracranial pressure exceeds Maximum capillaries pressure, then brain tissue becomes ischaemic and dies.

Spinal-cord injuries that leave permanent damage are rarely A result of a severed spinal-cord.

The vast majority of spinal cord injury occurs as a result of bleeding or swelling into the bony canal where the spinal-cord sits.  As the swelling or bleeding increases into this area, it places compression or pressure on the spinal-cord, this exceeds the capillaries pressure resulting in, you guessed it, ischaemia and cell death.

Glaucoma is a collection of disorders disorders that result in a blockage of aqueous humour, A fluid that is constantly being manufactured in the anterior chamber of each Eye.

As the pressure builds up inside the anterior chamber, this exerts compression across the entire globe of the eye. When this compression rises higher than capillaries pressure, then diffusion to the optic nerve is diminished causing optic nerve ischaemia and death. This results in permanent blindness if it’s not caught and treated .

So there you have it. The common denominator in all of these injuries and so so many other conditions that we try this nurses is compression or pressure that exceeds a capillary’s ability to perfuse its target tissue.

...

Always up for a dad joke so here’s today’s.

Bad puns, that’s how eye roll!! 

#KYJ

#dadjokesdaily 

#ECT4Health 

Still places at respiratory seminar and Trauma seminar .