BT_GS 1.36 Muscle relaxant pharmacokinetics

BT_GS 1.36 Describe the pharmacokinetics of neuromuscular blocking agents

TRUE/FALSE The short duration of action of succinylcholine is due to its rapid hydrolysis by acetylcholinesterase at the neuromuscular junction

TRUE/FALSE The volume of distribution of muscle relaxants imply that they are essentially confined to the intravascular space

TRUE/FALSE Antiepileptic inducers of CP450 increase the rate of elimination of vecuronium but not mivacurium

TRUE/FALSE About 30% of an administered dose of cisatracurium is metabolised by ester hydrolysis

TRUE/FALSE All muscle relaxants bind to alpha 1 acid glycoprotein

BT_PO 1.98a Physiology of Skeletal Muscle

I thought that this week, we could focus on the neuromuscular junction.

BT_PO 1.98a Describe the physiology of skeletal muscle including mechanism of excitation contraction coupling and compare the physiology of skeletal muscle with that of cardiac muscle.

TRUE/FALSE Most muscle fibres have only one neuromuscular junction.

TRUE/FALSE Activation of skeletal muscle acetylcholine receptors caused depolarisation by efflux of K+ ions.

TRUE/FALSE ATP can only supply energy for skeletal muscle contraction for 5-8 seconds.

TRUE/FALSE In the final stage of denervation atrophy, muscle cells have little capability to regenerate myofibrils.

TRUE/FALSE Skeletal and cardiac muscle act as a functional syncytium during depolarisation.

Study Tip – doing effective revision

Effective revision is an essential element of an effective study program. No matter how well you have summarised and understood a topic, without revision you will have forgotten 95% of the information within a month.

Therefore, your study timetable needs to have time allocated to revision. It is recommended to revise a new topic at “one hour, one day, one week, and one month” to limit the rate of forgetting. This is represented on an Ebbinghaus curve, below.


You need to have an organised system for doing this. Various methods are used, for example: an excel spreadsheet, coloured tabs on your index cards, or even just ticks on the top of your study notes.

Revision needs to be more than just passively looking over your notes. You need to actively engage with the material. Doing some SAQ’s is an excellent method, because this not only requires that you retrieve the knowledge from your long term memory, SAQ’s also ensure that you apply / use the knowledge in some way. Solving a problem is a great way of actively learning!!

Another (under-recognised) way of doing revision is to talk about primary material in theatre every day. We are surrounded by pharmacology, physiological alterations, and technology – so there is no excuse for not finding something to talk about … and revise!

Australia Day

Today you can enjoy a series of appropriately themed trivia questions ….

The ANZCA coat of arms depicts Andreas Vesalius standing on which native Australian plant?

When and where was the first documented anaesthetic given in Australia? How many years after Morton’s demonstration was this?

Which Australian anaesthetist (who worked at the Alfred in Melbourne) gives his name to the medal for the highest marks in the Primary Exam?

Which Victorian anaesthetist wrote the first Australian textbook on anaesthesia, and gives his name to the ANZCA museum?

Which Australian state produces about 50% of the world’s (legal) opium supply?


BT_PO 1.63 Describe glomerular filtration and tubular function

Daily glomerular filtration of potassium is approximately 800 mmol/day. TRUE / FALSE

Reabsorption of potassium in the proximal tubule is fixed at 65% of the amount filtered. TRUE / FALSE

Aldosterone controls potassium excretion by altering the amount reabsorbed in the distal tubule. TRUE / FALSE

An increase in plasma potassium concentration directly stimulates the Na-K pumps in the distal tubule, to increase potassium secretion. TRUE / FALSE

During hypokalaemia, the kidneys can achieve zero potassium excretion in the urine. TRUE / FALSE

BT_GS 1.21 Describe and give examples of the clinical importance of isomerism.

Diastereoisomers are two molecules that are mirror images of each other, because they have one chiral centre. TRUE / FALSE

Adrenaline preparations are racemic. They contain levo-adrenaline and dextro-adrenaline, which are equipotent. TRUE / FALSE

Ropivacaine contains only the S isomer, which has lower toxicity than the R isomer. TRUE / FALSE

Intravenous glucose solutions contain only D-glucose, because L-glucose cannot be used by cells. TRUE / FALSE

S-ketamine is not currently available in Australia. It would be advantageous, because the R enantiomer causes more hallucinations. TRUE / FALSE

BT_AM 1.1 Describe the anatomy of the upper airway, larynx and trachea, including its innervation and endoscopic appearance

The turbinates project into the nasal cavity from the nasal septum. TRUE / FALSE

When a curved laryngoscope blade is placed in the vallecula, it elevates the epiglottis by tensing the hyoepiglottic ligament. TRUE / FALSE

In an adult, cricoid pressure blocks the oesophagus by compressing it against the C3 vertebral body. TRUE / FALSE

The sensory innervation of the area just above the vocal cords is from the external branch of the superior laryngeal nerve. TRUE / FALSE

The surface landmark that corresponds with the carina is the manubriosternal joint (angle of Louis). TRUE / FALSE

BT_PO 1.48 Intergration of cardiovascular responses part 2

When I was writing yesterday’s post, I forgot that today would be Saturday ( that is what comes from being on sick leave and having children on holiday😉). Lucky you – an extra post this week!

BT_PO 1.48 Discuss the cardiovascular responses to:
· Changes in posture

· Exercise

· Valsalva maneouvre

· Positive pressure ventilation and PEEP

· Pneumoperitoneum

· Haemorrhage and hypovolaemia

· Surgery and trauma

The blood volume impacts on the cardiovascular responses of a patient undergoing the Valsalva Manoeuvre  TRUE/FALSE

Pneumoperitoneum with an intraabdominal pressure of greater than 10mmHg is likely to result in an increase in cardiac output TRUE/FALSE

Compensation which occurs following haemorrhage, aims to restore arterial blood pressure to normal TRUE/FALSE

Sympathetic stimulation associated with major haemorrhage results in significant coronary artery constriction TRUE/FALSE

The baroreceptor setpoint changes during excersice TRUE/FALSE

BT_PO 1.48 Integration of cardiovascular responses

Sticking with CVS physiology, another LO highly represented in the exam. I think I will stick with this topic tomorrow as well – stay tuned for part 2…

BT_PO 1.48 Discuss the cardiovascular responses to:
· Changes in posture

· Exercise

· Valsalva maneouvre

· Positive pressure ventilation and PEEP

· Pneumoperitoneum

· Haemorrhage and hypovolaemia

· Surgery and trauma

Coronary blood flow may increase 4 times resting level during heavy exercise

The cardiac output during exercise is higher than that calculated on heart rate and increased contractility alone

1000 ml of interstitial fluid can be absorbed during shock during the first hour

The Valsalva Manoeuvre can be used to test the integrity of the baroreceptors

A cerebrally mediated activation of the sympathetic nervous system occurs when the arterial pressure falls below 50 mmHg

BT_PO 1.45 Cardiac output

No pictures today, just an LO which features heavily in the SAQs and vivas.

BT_PO 1.45  Discuss the factors that determine and control cardiac output and the implications for clinical practice including:          
· Preload, afterload and contractility

· The Frank-Starling mechanism

· Cardiac output and vascular function curves

· Pressure volume relationships in the heart

The heart only has to work against afterload once the aortic and pulmonary valves are open and ejection of ventricular blood begins TRUE/FALSE

If afterload and contractility remain unchanged, increasing preload will result in a decreased end-systolic ventricular volume TRUE/FALSE

In sinus rhythm, atrial contraction contributes about 30% to the end diastolic ventricular volume TRUE/FALSE

A Frank Starling curve relates ventricular end diastolic volume to left ventricular pressure TRUE/FALSE

In normovolaemic patients, IPPV causes an increase in cardiac output TRUE/FALSE