BT PO 1.120 Pharmacology of anticoagulant drugs

Praxbind

This post will focus on the new or novel anticoagulant drugs (NOACs) which are taking over from warfarin thanks to effective marketing and their not needing regular monitoring. They continue to pose significant problems in the perioperative period especially in the setting of emergent surgery due to difficulties in antagonising their anticoagulant activity. Although idarucizamab works very well it still costs a bomb and only works for dabigatran. All the set texts cover these important drugs well. You need to know more than the surgeons about all these agents.

T/F  all these agents are given once a day

T/F  these agents have a reduced risk than warfarin of major bleeding

T/F  reversal drugs have been developed for all of the NOACs

T/F  prothrombinex will reliably reverse the anticoagulant effect of dabigatran because it is a thrombin inhibitor

T/F  normal conventional coags makes significant NOAC activity unlikely

Lastly, do you know the generic to match these brand names:

  • eliquis
  • pradaxa
  • prasugrel
  • xarelto
  • brilinta

(I may have been a bit sneaky)

Are these words spelled/ spelt correctly?

m kelly

No LO for correct grammar but each of the following words is notorious for being spelled incorrectly by candidates on SAQ papers. Although it probably won’t lose you points it is somewhat irksome to see words ubiquitous to anaesthesia being written incorrectly- especially when the correct spelling is provided in the question itself!

You should be very familiar with the following words in terms of their meaning and application to anaesthesia. They all do actually have a primary LO that relates to them. Regarding whether they are spelled correctly, the answer is only a brief Google search away but beware there are also plenty of websites and textbooks that perpetuate spelling errors. The picture above for instance….

 

Which of the following are spelled correctly?

Ropivicaine

Mallampatti

Alfentanil

Splanchnic

Substantia Gelatinoosa

Rapoport-Leubering shunt

Monro-Kellie Doctrine

Keety-Schmidt method

Primary Exam Webinar

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I hope that everyone has had a great week and is going to be able to do at least one enjoyable thing over the weekend. Maybe you’ll find yourself as happy and relaxed as these sea otters, off the coast of Carmel, California. They are some of my favourite creatures and have wrapped themselves in kelp, as an anchor to the seabed, just to reduce one more worry – that of drifting away.

Today, I little bit of a plug for the Tips for the Primary Exam Webinar which will be hosted by ANZCA next Tuesday July 10, 7.30 AEST.

The webinar will briefly outline the exam and then talk about ways to get the most from your exam sitting, addressing each component separately. The information will be applicable for those sitting the exam in August. However those planning to sit in February may also find it helpful and at the end there will be some general study advice, for those will a bit more preparation time.

The session has 100 spots available. You can register via the link above.

BT_PO 1.14 Explain the vertical gradient of pleural pressure and its significance

A viva or SAQ may ask you to compare the alveoli at the apex of the lung with those at the base when considering the subject in the upright position. This is core stuff and you would be expected to know all of the following although you may have to pause for thought with the last one. All the answers will be found in Nunn and/or West.

At end expiration apical alveoli are larger  T/F

Perfusion of the lung base is greater than of the apex  T/F

Ventilation of the lung base is greater than that of the apex T/F

PaCO2 of apical alveoli is similar to that in the conducting airways T/F

The overall V/Q ratio of the lung is about 0.8 T/F

The V/Q ratio in the lung apex is about 3.3  T/F

In the supine position all the regional differences in lung perfusion become insignificant and it functions as a homogeneous unit  T/F

BT_RA 1.4 Describe the anatomy of the vertebral column spinal cord and meninges relevant to the performance of central neuraxial block with appropriate surface markings.

Ellis and Lawson’s “Anatomy for anaesthetists” is worth a read through for some of the key areas of anatomy pertinent to anaesthetists. The answers to all of these are available there. In the exam you will be quizzed on a pretty narrow range of anatomy as it’s not easy to examine in a clinically relevant way without resorting to recollection of ‘factoids’. However, given the frequency with which you stick long sharp things into people’s spines, blindly aiming for a spot half the size of your little fingernail at seemingly ever-increasing distances from the surface, it behoves you to be au fait with the anatomy of the vertebral column and it’s contents.

T/F  the intercristal (Tuffier’s) line usually passes through the body of L3

T/F  the posterior rami of sacral nerves exit through the sacral hiatus

T/F  the dural sac terminates at L5/S1

T/F an epidural catheter advanced too far may exit the vertebral canal through an intervertebral foramen

T/F  the dural sac does not have posterior attachments

T/F  the subdural space is a potential space between the dura and arachnoid mater

Help to find some positive emotion

 

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Mermaid – Grand Prize Winner National Geographic Photographer of the Year

This morning I wrote a post on the benefits of cultivating and using positive emotion. Sometimes these emotions can be hard to find. I have just been looking at my emails and thought I must share this with you – the  National Geographic Travel Photographer of the Year  finalists and winning entries.

I would encourage you to scroll through the amazing photographs and feel the positive emotion flood through you….

Onset of local anaesthetic block

A lower tissue pH will increase the speed of onset of local anaesthetic block. TRUE/FALSE

An increase in progesterone, increases the sensitivity to local anaesthesia. TRUE/FALSE

A large nerve axon has a faster onset of action with the same dose of local anaesthetic, compared to a small nerve. TRUE/FALSE

Fick’s law of diffusion covers all of the factors that affect onset of a local anaesthetic block. TRUE/FALSE

Ropivicaine has intrinsic vasodilatory actions which may reduce its length of action. TRUE/FALSE

 

Duration of Non-depolarising Neuromuscular Blocking Agents

NDMRs with a long duration of action have a clearance rate that is limited by the glomerular filtration rate. TRUE/FALSE

Intravenous calcium can be used to hasten the recovery from neuromuscular blockade. TRUE/FALSE

Magnesium and Lithium have opposing effects on the duration of action of NDMRs. TRUE/FALSE

Hypothermia increases the duration of vecuronium induced neuromuscular blockade. TRUE/FALSE

A patient with a 40% burn 2 weeks prior, is likely to be resistant to the effects of NDMRs. TRUE/FALSE

Onset time for Non-Depolarising Neuromuscular Blockade

Increasing the dose of Atracurium from 0.6mg/kg to 1.0mg/kg, increases the speed of onset of intubating conditions. TRUE/FALSE

Sevoflurane will slow the onset of non-depolarising neuromuscular blocking drugs. TRUE/FALSE

The gender difference in sensitivity to NDMRs is insignificant. TRUE/FALSE

The onset of action of NDMRs in peripheral muscles (versus central) is slower primarily due to differences in blood supply. TRUE/FALSE

The most potent NDMR has the slowest onset whereas the least potent NDMR has the fastest. TRUE/FALSE

Ephedrine increases the cardiac output, which causes the NDMR to reach the effect site more quickly. TRUE/FALSE

The onset of NDMRs may be delayed in someone with poor nutritional status. TRUE/FALSE

 

 

Anaesthesia – a novel prevention for jet lag? Bee prepared to be amazed!

Above is one of the fabulous tapestries hung in Christiansborg Palace, Copenhagen. Commissioned by the current Queen, this one depicts the Vikings (great travellers themselves).

Having recently undertaken long distance travel across many time zones, the prevention of jet lag has been on my mind. Some of my friends swear by melatonin, especially the controlled release form. I am a fan of the natural melatonin stimulant – sunlight. Exposure to intense natural light is supposed to increase nocturnal melatonin levels and it is a good excuse to get out an explore wherever you have just landed!

That’s all well and good, but what is the relevance to the title of this post? One of the fellow authors of this blog, slowlywaving, recently regaled me with the fascinating story regarding evidence that anaesthesia interrupts circadian rhythms. It all revolves around the study of bees.

Bees have a stong circadian timer which governs much of their behaviour and also helps with their navigation in conjunction with the sun compass. Amongst other things it enables them to judge how much time has passed whilst they have been in the hive so that when they leave the hive, they can maintain their heading back to a great source of nectar, even though the position of the sun may have changed dramatically.

A group of researchers decided to use bees to test the effect of anaesthesia on circadian rhythms. In our initial discussion, the thought was that the bees were anaesthetised with propofol and there was some discussion about how this could possibly be achieved (anyone trying cannulating a bee? do they even have veins? you can find the answer here if you are interested). As it turns out, isoflurane was used and the bees received a 6 hr daytime anaesthetic.

On awakening from the anaesthetic, the bees behaved in a manner consistent with them sensing a time 4-5 hours earlier than the actual time. They headed off to find their food at the bearing it would have been at, relative to the sun, several hours previously! They did a whole lot of fancy genetic testing and determined that the effect was related to dramatic slowing of the circadian rhythm. How cool! Interestingly night time perception was unchanged, which apparently fits with the hypothesis.

So how could we use this to prevent jet lag? Just imagine being anaesthetised (it would be much easier with propofol than isoflurane, assuming that it has the same effect) prior to being put on your long haul flight. You are then awoken at the same hour that you were anaesthetised, but in your new location and, voila, no jet lag!! Do you think it would take off? (sorry…)

The other fascinating part of the story revolves around tracking the bees. It involves tiny radar transponders and a disused airbase, but perhaps that can be a story for another day….

For those of you interested I have posted a copy of the article at aGasgal’s site