BT_SQ 1.9

Dedicated scavenging pumps. The hospital vacuum is designed to suck up fluids, and usually vents in to the plant room of the hospital. The plant room staff will not thank you for connecting the scavenging to such a system. The anaesthetic gas scavenging system should be vented away from where people will inhale the gases.







T/F A risk of using a scavenging system is excessive positive pressure in the breathing circuit

T/F Active scavenging systems should be capable of developing a high negative pressure

T/F Prolonged exposure to trace concentrations of volatile agents my be teratogenic in the second trimester of pregnancy

T/F Passive scavenging systems should have a flowmeter to measure flow

T/F A closed scavenging interface must be used with an active scavenging system

Color coding of gases

BT_SQ 1.10

For the end of January puzzle: See how many safety and standards violations you can find in this picture!


One of my friends was telling me about an incident at her hospital a while ago, where the patient became hypoxic after being given 100% oxygen. The hospital had done some work on the piping, but hadn’t tested it or notified anyone…

T/F Nitrous oxide hoses should be colour coded light blue

T/F Oxygen hoses should be colour coded green

T/F Air hoses should be colour coded yellow

T/F CO2 hoses should be colour coded gray

T/F Scavenging hoses should be colour coded black and white


Bonus questions:

1. How are the gas pipelines themselves coded so the workmen know which outlet to connect them to.

2. (Non examinable) What qualifications do you have to hold to install a medical gas pipeline in Australia?


BT_GS 1.35 Describe the physiology of the neuromuscular junction and the mechanism of action of neuromuscular blocking agents

If you’ve done anaesthesia for burns patients then you’ll know there is one drug that you must not forget to not give! Less dramatic, but perhaps more important because of the larger number of patients affected, are stroke, critical illness or any prolonged immobility (good reason for regular breaks from study).


Prolonged immobility results in increased sensitivity to suxamethonium   TRUE/FALSE

Prolonged immobility results in decreased sensitivity to NMDRs   TRUE/FALSE

Prolonged immobility results in increased expression of ‘”immature” AChR isoforms   TRUE/FALSE

Immature AChR isoforms are more sensitive to ACh   TRUE/FALSE

The presynaptic AChR are mostly of the immature type   TRUE/FALSE

5 things you probably didn’t know about Archie Brain

I hope I am not being presumptuous in assuming that all of you know who Archie Brain is. The next sentence will give you a rather substantial clue regardless. I reckon his invention of the laryngeal mask was worthy of the Nobel Prize for Medicine. His invention is certainly the most significant advance in the field of anaesthesia for my generation. It is very fortunate that propofol joined the arsenal at roughly the same time. White stuff + LMA is probably the commonest anaesthetic combo in the world today. Interestingly enough the first anaesthetics using the LMA were done with a combination of thiopentone and muscle relaxant. Trying to insert a LMA with just thiopentone is fraught with peril but the contemporary anaesthetic trainee has barely seen a vial of thiopentone these days let alone tried to insert a LMA under the influence of this venerable barbiturate. For a fascinating and comprehensive history about all things concerning Brain and his invention one should consult Joe Brimacombe’s definitive Laryngeal Mask Anesthesia: Principles and Practice. I would confidently assert that Brimacombe has inserted more LMAs than anyone else on the planet. Despite the American spelling of his textbook he is a pom who practices in Far North Queensland. To say he is an ardent fan of the Proseal LMA would be an understatement. LMAs are so popular in Cairns that they mandate intubating people each April so they don’t forget what to do with a laryngoscope.

The Laryngeal Mask Airway (LMA) was just one of numerous patents that Brain applied for.  TRUE/ FALSE

The first published study involving the LMA was a case series of women undergoing gynaecological laparoscopy.  TRUE/ FALSE

The LMA was first commercially available in 1983.  TRUE/ FALSE

Australia was the first place to use the Proseal LMA.  TRUE/ FALSE

There are over twenty different methods described to insert a LMA.  TRUE/ FALSE

BT_GS 1.35 Describe the physiology of the neuromuscular junction and the mechanism of action of neuromuscular blocking agents

This is well-covered in Hemmings and Egan (Chapter 18). Giving neuromuscular blockers is one of the most risk-filled components of anaesthetic practice, so it’s worth knowing a bit more than how to draw a nice picture of the NMJ and the top 10 side-effects of suxamethonium…

Each muscle fibre is innervated by a single unmyelinated branch of a myelinated motor axon   TRUE/FALSE

Nicotinic receptors are sparse in the depths of the synaptic clefts of the post-junctional membrane   TRUE/FALSE

The perijunctional membrane has a high density of voltage-gated sodium channels   TRUE/FALSE

The number of quanta of Ach released is not affected by the extracellular calcium ion concentration   TRUE/FALSE

Each nerve impulse releases at least 200 quanta, each of about 5000 ACh molecules   TRUE/FALSE

The difference between the depolarisation caused by Ach and the threshold level needed to trigger an action potential is called the ‘safety factor’   TRUE/FALSE

BT_GS 1.44 Describe the clinical pharmacology of drugs used in the management of PONV


Regarding ondansetron:

It is significantly more expensive than metoclopramide*     T/F

It prolongs the QT period to a similar degree to that of droperidol     T/F

A common adverse effect is constipation                               T/F

It doesn’t impair the analgesic efficacy of tramadol             T/F

The wafer formulation has an intense bitter taste                 T/F


*At the time of writing, an amp of Maxolon costs about 40 cents in my hospital.

A bit of light relief – yum!

I thought we all needed (well I certainly did) a bit of light relief after a whole week of BT_PM1.3.

A bit of light relief is an essential component of any study programme.

This not particularly scientific article suggests a number of ways in which you can improve your concentration span, most of which seem quite sensible.

One of their suggestions is to take a break.  If you have been following the blog for a while, you may know that I need little excuse for a break.

One of my favourite things to do, if I just need a mental break, is to bake!

To me baking has numerous advantages:

  • the process itself is quite meditative
  • it requires no real brain power, just follow the recipe
  • it makes a bit of a mess – quite therapeutic in my books
  • you end up with something delicious at the end
  • the end product can be consumed on a future breaks, perhaps with a cup a coffee, to improve your concentration even more (see link above)

Below are a few of my favourite simple recipes. Believe it or not, I am not really one to photograph food, so you will have to use your imaginations. These recipes are pretty well bullet proof and very tasty (especially if, like me, you LOVE ginger and rhubarb).

The easiest of all, Chatter’s Crack, I have already shared with you here.

The next one Gingerbread, from my friend Eliza

  • 110g unsalted butter
  • 110g golden syrup
  • 110g treacle
  • 225g plain flour
  • 1 tsp bicarbonate of soda
  • 1 tsp mixed spice
  • 1 dessertspoon ground ginger
  • 60g caster sugar
  • 150ml milk
  • 2 medium sized eggs, beaten

Ginger syrup

  • 100g caster sugar
  • 100ml water
  • 5cm piece fresh root ginger peeled and grated

Preheat oven to 150ºC (not sure whether this is fan forced or not. I have tried both and didn’t make much difference, but I would go with fan forced if available). Grease and line a 900g loaf tin.

Melt butter, syrup and treacle together in a saucepan over low heat. Sieve the flour, bicarbonate soda and spices in a bowl, add the caster sugar and mix well. Add the syrup mixture, milk and eggs and mix.

Pour into the prepared tin and bake for 40mins or until cooked (Eliza says an extra 5-10 mins). [N.B This is a moist cake]

For the ginger syrup, dissolve the sugar in the water with the ginger over low heat and boil for 2 mins.

Remove the cake from the oven and drizzle with the ginger syrup whilst still hot. Allow to cool in tin before serving. Keeps for a week (so I am told – it never lasts that long at our place!)

Third, from David Herbert’s Best Ever Baking Recipes. Super easy, delicious and also pretty foolproof.

You can see that this one is a favourite (and that I am a messy cook!)

And last of all, this is the cake I think I have cooked the most of any, in the 22 yrs since the book it is in, Stephanie Alexander’s A Cooks Companion, was published. The oven temperature is for conventional, not fan forced (drop to 140C if using fan forced).

I will concede the current weather is not ideal for baking, but I encourage you to give one of these a go the next time you need a bit of light relief.

BT_PM 1.3 Describe the physiology of descending inhibitory pathways

I think this will be may last post on this topic for a little while.

We might need some light relief tomorrow and then I am off on holidays -yay!

I think the descending inhibitory pathways are great and should be celebrated in all of us – life would be a bit grim without them…..


However, this sort of descending pathway I could easily live without- terrifying! (Bell Tower, Trogir, Croatia)

BT_PM 1.3 Describe the basic physiological mechanisms of pain including:


· Mediators, pathways and reflexes


Descending inhibitory neurones synapse in the region of the dorsal horn TRUE/FALSE

Relative lack of pain sensation in an extreme  “fight or  flight” situation is likely due to descending inhibition  TRUE/FALSE

Descending inhibition of nocioceptive input is inactive in our normal resting state TRUE/FLASE

Cannabinoids facilitate descending inhibition   TRUE/FALSE

Placebo analgesia may be mediated by increased activity of descending inhibitory pathways   TRUE/FALSE

BT_PM 1.3 Describe the central processing of pain

In the protracted series on this LO, today we have made it to the brain. Again a complex area, but one where it is important to have some fundamentals sorted in your minds.

Version 2

I thought you might need something beautiful today as an antidote to all the pain… Here is the inverted dome ceiling of the Palau de la Musica in Barcelona. The whole building is amazing and the ceiling even more sublime in person

BT_PM 1.3  Describe the basic physiological mechanisms of pain including:

• Central processing of pain


Nuclei in the lateral thalamus mediate the processing of the sensory and discriminative aspects of pain   TRUE/FALSE

The amygdala is involved placing pain within an emotional context, which may enhance to inhibit the pain experienced     TRUE/FALSE

The primary somatosensory cortex is involved with both sensory and emotional processing of pain    TRUE/FALSE

Nuclei in the medial thalamus have projections to areas involved with the affective experience of pain      TRUE/FALSE

At the level of the brainstem, and through associated neural networks, there is modulation of the autonomic response to pain  TRUE/FALSE

BT_PM 1.3 Describe the physiology of signal conduction in relation to pain

I am going to interpret this as signal conduction from the periphery to the brain, in other words, conduction along the primary and secondary (or projection) afferents.


This is definitely an area where you don’t want the wires getting crossed…… (photo Ho Chi Minh City)

BT_PM 1.3  Describe the basic physiological mechanisms of pain including:

· Conduction


Voltage gated sodium channels are important in normal and abnormal transmission of signals along the primary afferent neurone  TRUE/FALSE

Increased potassium conductance in the primary afferent neurone will tend to enhance signal transmission    TRUE/FALSE

Nociceptive-specific projection afferents predominate in Rexed lamina I and respond exclusively to noxious stimuli   TRUE/FALSE

Wide dynamic range neurones receive input from visceral and somatic sources TRUE/FALSE

Activation of NMDA receptors, on the post synaptic membrane, occurs readily at normal signal transmission strength TRUE/FALSE