Exam Intelligence

“The Anaesthetist’s toolbox”

This gem of a website contains some very useful presentations buried on the learning link, found in the top of the toolbar.

Written by some South Coast trainees, the presentations are not only useful for revision, but they also very kindly seem to have made them available to help others who need to write a presentation at short notice.

Very kind!

GasLog - The Anaesthetist’s Toolbox

I know, I know.

I apologise.

I sat down and talked to a couple of people where I work who have just passed the written exam (and Well Done! to everyone who did!).  They were saying that one of the things they are struggling with now is the ability to vocalise everything that they have learned.

The answer, I’m afraid, is to do exactly that.  Even if you’re the shy retiring type, in fact particularly if you are, you need to verbalise.  Burst out in the middle of your lists with comments about each of the drugs that you are using: “Propofol is fascinating, don’t you think?  It’s chemical structure based on a phenol ring looks just like a snowman, yes?  Here, let me show you…”  (You need a bit of an eye of faith, but look at it the right way, and it does.  Trust me!)

Also, this is the time where you find out just how much your partner loves you, and who your good friends are.  Give your loved one the Bricker viva book, and get them to ask you questions about Ketamine, pain pathways blah blah.  They don’t have to understand it, but it helps if they can bluff their way through by reading ahead!

Also, if you struggle with being concise, try this:  The Five Word Viva Game.

Anyway, good luck!

I think that if you keep the basic principles in mind this is quite simple to understand.

Firstly decide on what side of tube you need, a left or a right. i.e. do you want the left or the right bronchus to be intubated. So in exam speak;

“This will depend on patient factors and surgical factors.”

A right sided tube will generally pass into the right bronchus more easily due the more direct angle the right main bronchus branches from the trachea. So for many procedures on either the right or the left lung or pleura a right sided tube is often selected.

Sometimes the tube could get in the way of the surgeon for example, if a right pneumonectomy needs to be performed, for example, the right bronchus may need to be resected which means you can’t put a right sided tube in there!

Another indication for a specific sided tube may be to protect a lung from an infected lung on the other side.

There is some interesting physiology which occurs when ventilating only one lung, and http://ourworld.cs.com/_ht_a/doschk/onelung.htm contains some useful descriptions of the physiological changes.

It is worth remembering the following points though:

1. As always consider the West Zones creating a starling resistor in the upper zones of the dependant lung. Here the flow of blood through the pulmonary capillaries is reduced due to the effects of gravity and can be occluded completely if the alveolar pressure is higher than the hydrostatic pressure in the capillary. Remember also that in the horizontal position the West zones become horizontal.
2. When inflating the upper lung after the operation, the clamp is often switched to the dependant lung for the first few breaths to direct all the pressure to the collapsed upper lung. The reason is that otherwise, the collapsed upper lung will offer a higher resistance to the air flow than the already inflated dependant lung (LaPlaces’ Law). In other words the already inflated balloon (the lower lung) will be much easier to blow up than the fully deflated balloon (the upper lung). So, with the dependant lung clamped, all the ventilation pressure is directed to inflating the collapsed lung. Obviously don’t forget to unclamp the dependant lung after a few breaths!

From SuneilR

Image via Wikipedia

Someone asked me to produce an answer for a question that gave an idea of how much needed to be written.

I’ve shown you examples of good and bad layout, but here is an answer that could be considered as having sufficient content to gain a pass.  It must have done, because I wouldn’t have passed the April 2008 SAQ paper otherwise!

The question I am answering is about pre-oxygenation and is question 5 in the April 2008 paper which you can find by clicking here.

A)    Method of Pre-Oxygenation

• Ask patient to breathe normally (normal tidal volume) for 3-5 minutes,
• Via face mask tightly applied to face,
• Connected to circle-absorber system,
• With fresh gas flow of 100% oxygen of >minute volume.

B)    Physiological basis

• O₂ consumption is approximately 250ml min^-1.
• FRC is ≈ 2500ml
• Preoxygenation replaces nitrogen containing air in the lungs with oxygen and generate reservoir of ≈ 2500ml oxygen.
• Oxygen saturation therefore maintained in apnoeic patient for 5-10 minutes.
• Also, small increase in oxygen reserves within body tissues.
• Duration required for preoxygenation is dependent on washin of oxygen and washout of nitrogen and can be decreased by patient increasing per breath volume (4-breath and 8-breath techniques).

C)    Assessment of adequacy

• Measure end-tidal oxygen concentration (>85% indicates good preoxygenation)
• Measure time for SpO2 to drop below 90% from onset of apnoea
• Measure arterial oxygen tension using arterial blood gases
• Mass spectrometry of expired gas

D)    Advantages of PreO₂

• Increases time to desaturation during securing an airway

Disadvantages

• Absorption atelectasis (airway closure followed by absorption of distal gas)
• Atelectasis due to airway narrowing (gas in alveolus absorbed faster than can be replaced through narrow airway)
• Patient anxiety heightened by tight fitting face mask (”I can’t breathe”) (increases oxygen demand)
• Potential to mask oesophageal intubation by delaying desaturation (offset by EtCO₂ monitoring in modern practice).

Now that’s my answer to the question.

It isn’t perfect, but I think it’s pretty good (and I want to hear from anyone who thinks it needs modifying: help-me@examintelligence.com).

I don’t think you need to write any more than that.

On another note:

James has written a Sexy Topics list over at Passing The Final, which I highly recommend you read.  It contains a lits of topics which are prime fodder for the SAQ.  Like him, though, I urge you not to underestimate the MCQ!

Good luck!

Image via Wikipedia

Whilst I was revising for my exam, I did not really take much note of the college Bulletin, which comes with the “Blue Journal” every other month.  I have started reading it again, and in doing so came across several references to an article from March 2008, written by an airline pilot, about the death of his wife under anaesthesia for an attempted ENT operation.  It is quite a tragic case, from which he hopes anaesthetists will learn.

In summary, she had no medical or anaesthetic conditions of major concern, there was slightly reduced neck movement which wouldn’t have worried anyone, airway assessment did not indicate a potentially difficult airway.  The procedure was a straightforward endoscopic sinus surgery and septoplasty.  The plan was to use an LMA which unfortunately could not be inserted at induction, and tracheal intubation proved extremely difficult.  She became hypoxic and could not be ventilated and was eventually allowed to wake up, but unfortunately had had a prolonged episode of hypoxia, and died with extensive brain damage on an intensive care unit 13 days later.  Now this is a grossly simplified summary, and I highly recommend you read the article on page 17 of issue 48 of the RCOA bulletin along with a summary of the case written by Prof Michael Harmer (former president of the AAGBI) at the Clinical Human Factors Group website for more details.

The reason I am writing about it is because it is another one of those safety issue questions that might come up, and something that everyone should be aware of.  I have never been unfortunate enough to be in a “Can’t Intubate, Can’t Ventilate” situation myself, but have become involved in a case where a QuickTrach has been inserted immediately prior to my arrival (without which that patient would certainly have died).  I can tell you that the danger of “fixation” that the pilot talks about is a real danger, and one which I have seen happen to people, and if I’m honest, has happened to me when trying to solve problems, at least outside of work!

My thoughts on this are that whenever you encounter serious difficulties, you should summon assistance, preferably of at least the same level of skill as you, but failing that, any other pair of eyes, hands and a different perspective on the situation can help.  (An aside here:  sometimes, when you can’t figure out something, it’s worth “brainstorming”, but in a non-judgmental way, by which I mean you brainstorm everything, and don’t disregard it immediately out of hand because you judge it to be a bad idea.  The reason for saying “non-judgmental” here, is that you may be fixated on the problem being one thing, but actually it is another, so you throw away a solution without consideration, because you’re looking for a solution to the wrong thing.  Never forget to listen to people.  Sometimes their ideas will be stupid and silly, but sometimes they will come up with a gem…)

Secondly, when you get into difficulty, take a few seconds to think about what you are ACTUALLY trying to achieve.  Are you really trying to intubate, or are you really trying to oxygenate?  Are you trying to save someone’s life by decompressing their tension pneumothorax, or trying to practice your sledinger chest drain insertion?

Thirdly, always look back at what you did, preferably with someone who wasn’t there (though this may be impossible) who can understand the situation (no point talking it through with the diabetes clinic HCA in this instance, is there), and try to figure out what went wrong, what could have been done differently, and why it wasn’t done differently.  The most important thing is that there should not be any attempt to apportion blame. It’s not about “It was your fault.  You didn’t do this or that”.  It’s about “Next time we should make sure that the following things happen…”.

Anyway, back to the point, after all, this is a website about passing the FRCA, right?

There are a number of guidelines and protocols out there about how to manage a failed or difficult intubation, but for the purposes of the UK exam, I suggest you stick to the ones you can find here at the Difficult Airway Society.  Other countries have slightly different guidelines, but the bottom line is, that the idea is to get oxygen in by whatever means is necessary, with the two ultimate (more desirable) outcomes being  a surgical airway, or a spontaneously breathing awake patient (never forget that an awake patient is a possibility for getting yourself out of trouble!).