2018.1 SAQ 5

BT_PM 1.12 (Opioid receptors)

List the desired and adverse effects of opioids and the corresponding anatomical location of the receptors being activated

Opioids have multiple sites of action and many of their effects are undesirable. These should be considered in your patients, and other analgesic techniques used if harms potentially outweigh benefits.

Opioids can mediate analgesia through presynaptic primary sensory afferents T/F

Opioids can mediate analgesia in the dorsal horn of the spinal cord T/F

Opioids have no supra-spinal mediation of analgesia  T/F

Immunosuppression is an adverse effect of opioids T/F

Biliary spasm is an adverse effect of opioids T/F

Bonus question, definitely not core material in answering this question but interesting. First paragraph of the pethidine entry on wikipedia leads you to the answer but it’s worth considering why the Germans were trying to develop drugs of this class in 1939.

Pethidine can cause mydriasis T/F

Reading your feedback in 2018 part 1

mcq feedbackBy now those who weren’t successful in meeting the requirements of the primary examination will have received their feedback letters. A difficult read which I’d like to try and make easier by helping you approach logically. This isn’t official advice, just what I would recommend to any SOT or candidate who approached me for help. I’ll talk about looking at the MCQ marks today.

I’ll be including photos of a feedback letter I’ve created for an imaginary candidate. Here are their MCQ marks. The candidate passed the MCQ and I would like to take this opportunity to say well done to everyone who passed the MCQ. You’ve demonstrated a great breadth of knowledge covering over 300 LOs. This requires significant organisation and diligence. Even if you didn’t go on to be successful in the overall exam this is a great achievement.

This candidate has only just passed the component though, and I’d recommend people in the 75-84 range realise they have a good base but they should try to improve this component to safely pass in their next attempt. More ruthless organisation and diligence is the key here. Aids I would recommend would be The Primer for the Primary which I’ve recently recommended, and a new resource which will be released soon at mak95.com. I’ve spoken with registrars who have used a beta version of this and they have given glowing reviews.

Low scores in this component mean you haven’t demonstrated a foundation in the basic sciences in anaesthesia, and it may well be very difficult to build this over just a few months. If training requirements allow it might be best to build up to sit in 2019.

2018.1 SAQ 4 Hazards of CO2 absorbents

Outline the hazards associated with the use of CO2 absorbents within a circle breathing system and how the risks can be minimised.

We use a CO2 absorber as part of a circle circuit on a daily basis. It is important to be cognisant of potential hazards associated with its use. The CO2 absorbents are continually evolving to help eliminate some of the absorbent specific risks, but the are a number of general risks that exist regardless of the absorbent used.

Miller’s Anaesthesia Ch 29 covers this topic well, including a discussion of the newer Ca(OH)2 and LiOH based absorbents.

Please note however that there is an error in Miller with regard to soda lime and Compound A production. Compound A production and buildup is favoured by dry soda lime, contrary to what Miller says. I have been in contact with the editor regarding the mistake.

The risks of using desiccated absorbent, especially those containing strong alkalis, are significant and it is important to be mindful of this.

BT_SQ 1.15 Outline how CO2 is absorbed in a circle system and the hazards associated with the use of CO2 absorption

4-8 mesh granules provide the optimal balance between surface area of CO2 absorption and resistance in the circuit  T/F

Ultra low flow anaesthesia (<0.5L/min FGF) increases the risk of carbon monoxide (CO) buildup in the circuit  T/F

Higher fresh gas flows, may increase the rate of CO production by drying the absorbent T/F

The CO2 canister is a common site for a circuit leak T/F

Inspiratory CO2 monitoring is a less reliable measure of detecting expired CO2 absorbent than a pH sensitive dye T/F

The use of sevoflurane or a Ca(OH)2 based absorbent will prevent potential CO poisoning T/F

2018.1 SAQ 3 Mechanisms of anaesthesia

BT_GS 1.49

Outline the theories, both current and discredited, as to how volatile anaesthetic agents cause loss of consciousness.

This is an issue which is currently in the media. It also serves as a cautionary tale about how mathematics can be misused to prove what you wish to see. A log-log plot will often make variables appear to be linearly related, particularly if points which are not on the line are discarded.

Some questions inspired by common misconceptions in the SAQ:

T/F Mammals have cell walls, in which volatile anaesthetic agents dissolve

T/F The mechanism of anaesthesia is a combination of cerebral oedema, hypoxia and hypercarbia

And some more serious ones:

T/F volatile agents cause immobility by acting on the GABA receptor

T/F volatile agents cause effects at the 5HT3 receptor

T/F the effect of volatile agents on lipid bilayers can be mimicked by a change in temperature of 1°C

T/F volatile agents do not exhibit isomerism

T/F xenon and nitrous oxide induce unconsciousness by actions on the GABA receptor

2018.1 SAQ 2 CVS changes with morbid obesity

Describe the cardiovascular changes that occur with morbid obesity.

In the 20 yrs since I started anaesthesia, an increasing number of our patients are now morbidly obese. Obesity has implications for most body systems, but the interaction of the drugs we use with the cardiovascular system, makes this of particular relevance to us.

I have previously written a post on this topic where I have suggested some good resources. I would suggest you look at that post if you would like some further reading material (and also some more T/F statements to check your knowledge)

BT_PO 1.50 Describe the cardiovascular changes that occur with morbid obesity

Stroke volume increases linearly with BMI in part due to an increased preload  T/F

In the absence of another pathology, systemic vascular resistance is reduced in the morbidly obese T/F

All of the hormones secreted by visceral adipocytes are detrimental to the CVS  T/F

Both concentric and eccentric hypertrophy of the left ventricle occur in morbid obesity T/F

Morbid obesity is a hypercoaguable state T/F

 

 

2018.1 SAQ 1

Anatomy of the nose, mouth and larynx

IT_AM 1.1 Describe the basic structural anatomy of the upper airway including the larynx
BT_AM 1.1 Describe the anatomy of the upper airway, larynx and trachea, including its innervation and endoscopic appearance
BT_AM 1.2 Describe the physiology of the airway including airway reflexes

For specialist anaesthetists, the importance of an advanced level of knowledge of airway anatomy hardly needs stating! Your understanding of airway anatomy becomes incredibly important with a difficult intubation, especially when the anatomy is distorted. 

 

T / F  the nasal cavity needs to be cooler than core temperature, in order to function as a heat and moisture exchanger

T / F  Figure 1 shows the nasal turbinates in coronal section on a CT scan. They are abnormally large in size.

T / F  Figure 2 is the view with a fibreoptic scope just inside the LEFT nostril. A = nasal septum, and B = inferior turbinate. The scope should be advanced via X rather than Y.

The following questions all relate to Figure 3.

T / F  A = arytenoid cartilage. Although there is a corniculate cartilage at the apex of the arytenoid, the corniculate is very small, and doesn’t contribute much to the size of the visible “bump”.

T / F  B = posterior commissure. This is the groove formed where the left and right aryepiglottic folds meet posteriorly. With a difficult laryngoscopy, it may be the only visible laryngeal structure.

T / F  C = pyriform fossa. This is commonly the location of foreign bodies (e.g. fish bones), or the place where nasogastric tubes get caught. The pyriform fossae are continuous with the upper oesophagus.

T / F  the sensory innervation of X is the same as for the vocal cords

airway SAQ pics

A little time to pause and reflect

I saw that there was no post scheduled for this morning – I suspect everyone is a bit exhausted after this week’s vivas!

I thought I would take this opportunity to encourage you to take a moment to pause and reflect….

Sometimes in our busy lives it can be easy to lose sight of what is truly important to us. We get carried along by the tide of work, study and other commitments as life rushes by.

Some people will be elated this week having just passed the exam, whilst for others the feeling may be at the other end of the emotional spectrum – angry, frustrated, despondent.

Wherever you are placed, take some time to stop and think about who and what really matters to you. It may take some careful consideration to still your mind enough to locate the answer, but when you do, celebrate it.

I hope that everyone has a relaxing and peaceful weekend – you all deserve it. I am on holidays now, looking at the view above, and am looking forward to some time to pause and reflect myself.

Anticonvulsants

BT_PO 1.99  Outline the pharmacology of anti-depressant, anti-psychotic, anti-convulsant, anti-parkinsonian, and anti-migraine medication

 

T / F   in the ampoule, phenytoin is formulated in alcohol and ethylene glycol, making it prone to cause thrombophlebitis

T / F   phenytoin has very high oral bioavailability, so the IV and oral doses are similar

T / F   both phenytoin and levetiracetam require blood level monitoring

T / F   levetiracetam causes a “voltage dependent” block of voltage gated sodium channels

T / F   levetiracetam is only available as an oral medication

BT_RA 1.14 Describe factors influencing dose and choice of anaesthetic agents for spinal anaesthesia

OLYMPUS DIGITAL CAMERA

Something with many spines…. (Ecuador)

This is a very clinical LO, and something that you have probably thought about when performing spinals yourselves. The LO also talks about epidurals, but I think we can tackle that in a separate post.

Why is it that we use bupivacaine almost exclusively as our local anaesthetic in the subarachnoid space?

Miller’s Anesthesia 8e Ch 56 gives a detailed description of this topic.

BT_RA 1.14 Describe factors influencing dose and choice of anaesthetic agents for spinal anaesthesia and epidural anaesthesia/analgesia

If other factors are kept constant, an increased dose of local anaesthetic (LA) will usually result in a higher block T/F

Use of a hyperbaric LA solution increases the ease of obtaining a saddle block T/F

Transient neurological symptoms have been associated with the use of lignocaine with 5% dextrose T/F

The addition of adrenaline to LA in a spinal anaesthetic may improve analgesia by direct α2 agonism  T/F

The addition of clonidine to a spinal improves analgesia without prolonging motor block T/F

 

BT_RT 1.7 Describe blood groups and the physiological basis of transfusion reactions

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As a person with an O negative blood group who has had children, I find the physiology of blood groups quite interesting. I feel very thankful for the free availability of Anti-D [Rh(D) immunoglobulin], in Australia, as I suspect my second Rh positive child would, if she knew the potential implications for her.

In Australia, the source of Anti-D is still kind volunteers who have be sensitised to the Rhesus antigen. Here is a newspaper article celebrating 50 yrs of use of Anti-D ( a warning that the start of the story mentions an intrauterine foetal death. However, the the story as a whole is quite uplifting)

BT_RT 1.7 Describe blood groups and the physiological basis of transfusion reactions

ABO blood groups are named according to the presence of A or B antigen on the red blood cells T/F

Antibodies form in plasma against non self antigens  T/F

A person with O blood has no antibodies to ABO blood groups in their plasma  T/F

ABO incompatibility occurs when the recipient’s antibodies react with the donor antigen T/F

Only people who are Rhesus negative can develop Anti-D antibodies T/F