Sunday, 3 January 2021

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 : )

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!! 




Still places at respiratory seminar and Trauma seminar .

Saturday, 25 July 2020

Assessing Pain

Are you assessing pain ?

One of the most neglected skill sets of a clinician, is pain assessment.   Much has been written over the years but two themes reign supreme.
1- pain is what the patient says it is.
2- we are not good at assessment of pain.

As a subjective phenomenon, it is difficult to measure. So, do you use a system?  Have you got a template or a mnemonic you use when assessing a patient for pain.

O -Onset 
Asking about what brought the pain on.  Was it sudden, or a chronic ache that has been there long term. This lets the nurse drill down on any acute change in the pain .

P-Palliation /Provocation
Palliatition is easing or symptoms and provocation is worsening.  So ask your patient what makes their pain better or worse.  Has positioning, analgesia at home, or hot/cold pack made any differences?  Is the pain worsened on movement, palpating, or position? In chest /abdo pain, dies deep breathing alter the pain?  In leg ulcer patients, is their pain worse when they hang their legs down (venous congestion) or worse when elevating (arterial)- called claudication; this is the difference between venous or arterial disease.

Asking the patient to describe pain.  This can be difficult for the patient to articulate, so I use this question like a multi choice question.  People might identify if you say others describe their pain as “sharp, dull, stabbing,burning, shooting, electric, heaviness, aching, pressure, throbbing, spasming, cramping etc”. Is there altered sensation like numbness, pins n needles or intermittent tingling? Can you think of others?

R-Region and Radiation
Where exactly is the pain at its worst? Can they pinpoint the pain by pointing to where it hurts most?  Some is vague regional pain eg abdominal or cardiac pain, others are isolated pains like fractures, and epigastric pain.
Ask the patient if the pain radiates or spreads from a focal point to somewhere else.  Typically, cardiac pain radiates from the centre of the chest into the neck, jaw, teeth and arms (L>R).  Some abdominal pain can radiate to the shoulders, and some back pains can send electric shooting pain down the buttocks and back of the legs (sciatica).  

Pain scores have been around for a long time in visual (Wong-BakerFace scale, slide rule descriptor) and numeric 0-10 scoring systems.  These are hard for many patients to interpret and the most inaccurate part of a pain assessment.  Part of the problem with their use is inconsistency that nurses and paramedics apply the pain score.  
0 is no pain.  10 is the worst pain experienced.  It is finite, it is recognisable and it is something that the patient needs to reflect on NOT imagine.   You can not imagine a pain you have never felt, so stop expecting a patient to do this.  Never say.
“10 is the worst pain imaginable”. It isn’t.   10 will only ever be the worst they’ve remembered.  So should your patient suggest they have never experienced pain worse than this pain right now; then take them at their word, and record it as 10.
Soon you will intervene to ease the pain, so you will want to reevaluate the score after positioning or giving analgesia.
0= no pain:  10 is the worst they’ve ever experienced.
Even if they are laughing or won’t get off their phone!!  Frustrating I know, but it’s not a number they need to get right, nor one that you should judge them on.

Get a time line on the patient pain.  How long have they had this pain, is it there now? If not when was it there, and for how long?  If it is intermittent, how long is each episode?

Now the data is collected, a physical inspection or palpation may be valuable to aid your assessment.  Use range of movement assessment to put limbs through their paces.  Observe patient posture, positioning and any self protective guarding.   Look for inflammatory signs - red,hot,swollen.
And obtain a tidy medical history, including medications the patient is on.... I use AMPLE and I’ll look at that in the next blog.

So that’s it.  OPQRST.  In a simple template you can follow every time you’re assessing pain.  I hope it was a helpful refresher. 

I’d love to hear your thoughts and opinions, tips and tricks.

Sunday, 7 June 2020

ECTopics :17 Claiming CPD

Do you know how to diarise your CPD? In this short podcast, I discuss the standard reflection. Get through your next CPD NMBA audit with my Rule of Threes.

ECTopics :17 Claiming CPD

Monday, 18 May 2020

Ectopics :12 Comedian Georgie Carroll **Explicit Language and adult content**

Ectopics :12 Comedian Georgie Carroll **Explicit Language and adult content**

Had a great chat with Adelaide nurse, and Standup comedian Georgie Carroll. 
Born and raised in Manchester, England; now a proud Australian. Georgie Carroll is a Comedian, Nurse, Wife and Mother. 
This combination of Nationalities, home life and hospital has provided a 24/7 training ground that has nurtured Georgie’s naturally funny bones. Her bluntness and charm coupled with razor-sharp wit, give her a broad-spectrum appeal that can be put into any room and shine. 
this podcast features a free flowing (mostly) unedited fly on the wall type ear, of our chat that lasted the best part of 40 mins.   Like some Nurse to nurse conversations had in the privacy of comfortable company, there is a language disclaimer and some dark and risque content.  But all in all , its just fun chat with talented nurse, mother, and all round great conversationalist.
Catch Georgie's own Podcast called THE SWAB  on all your fav podcast apps.
Or flick over to her webpage -
#georgiecarroll #TheSWAB #ECTopics  #ECT4Health

Friday, 15 May 2020

A 5th category of Shock: Pneumogenic

A fifth category of shock - Pneumogenic

Are we missing a vital category of shock? 
Forever- we have had shock classified into 4 main categories, but is there a fifth?

Hypovolaemic - that is a reduction  in blood volume. 

Cardiogenic- that is a reduction in cardiac output

Obstructive - which is an obstruction to venous return and this preload.

And Distributive which is a venous dilation which causes a maldistribution of blood between arterial and venous capitance.

The point is- they are all shock which can be defined as Global Cellular Hypoxia- Lack of oxygen to all cells is the fundamental definition of shock.

So with shock being one thing (global hypoxia), why wouldn’t Respiratory failure contribute to shock?   It should.
I think the clever books have missed a category.

So I’m advocating a 5th category - Pneumogenic shock.

All tissue /organ oxygenation starts with delivery of oxygen via the arterial network.
The right heart receives blood from the tissues, pumps it into the lungs, to be oxygenated, receives it into the left heart, then pumps this oxygen to tissues- thus completing the circuit.

Traditionally in shock we have categorised every step in this circuit, except the glaringly obvious issue to oxygenation of blood inside pulmonary vessels.

The world of respiratory medicine goes to great pains to highlight the importance of understanding the physiology of VQ ratios, PF Ratios and A-a gradients, but stop short when translating this hypoxaemic discourse of respiratory failure to the concept of shock.

It therefore seems rational to add a unique category into the age old shock paradigm.  I propose “pneumogenic shock” to describe an aetiology of profound  global hypoxia born from a respiratory failure, not a cardiovascular failure.

Definition - Pneumogenic Shock, is a syndrome of hypoxaemic hypoxia caused by pathophysiological conditions that prevent adequate oxygenation of blood  (external respiration).
Pneumogenic shock would be classified as pre-pulmonary or extrinsic, and intrapulmonary (intrinsic).

Extrinsic Pneumogenic shock (EPS)
EPS occurs when a person is exposed to a reduction of oxygen in the gas mix being breathed.  EPS could manifest with toxic gas inhalation, or hypoxia environments.  It’s estimated that Fio2 of less than 0.15 (15%) is not sustainable for life at sea level barometric pressure.
Therefore breathing a smoke filled toxic gas environment where partial pressures of oxygen are too low would be considered to constitute EPS.

Prepulmonary Pneumogenic shock would manifest as a factor of airway obstruction, or restriction.  Foreign body airway occlusion (FBAO), mechanical suffocation, strangulation/hanging, and upper airway, larynx, tracheal or bronchial oedema, are all examples.
They may be manifestations of trauma, infection or other triggers of inflammation to the upper airway.  Fundamentally, shock caused by this subcategory are not associated with low Fio2, or alveolar dysfunction.

Intrinsic Pneumogenic Shock 
This Pneumogenic shock is intrapulmonary.  Where gas exchange occurs in alveoli, a mismatch of VQ ratio leads to an A-a gradient that is incompatible with survival.
In instances of severe pulmonary oedema, pulmonary embolism, low airway injury, ARDS or acute lung injury; gas exchange may become so impaired that hypoxaemia is critical.  
 A measure of PF ratio and V:Q would be assessment data that differentiates Pneumogenic shock from other syndromes.

I’m Rob Timmings a nurse educator.
The thoughts on this page are my own.  Not the position of ECT4Health, it’s directors or employees.  Rob Timmings is open to discussion on the content in this article.  It exists as a discussion paper.