BT_PM 1.17 Pharmacokinetics of intravenous opioids and clinical relevance

I am not a massive fan on memorising a whole lot of numbers for the sake of it – boring!!

However, sometimes these pesky numbers can actually help us guide clinical practice and, in that situation, they take on a whole new level of relevance. The pharmacokinetics of opioids are a case in point.

Hopefully no opioids in this handbag (although to be honest, I couldn’t be sure) Cottesloe, WA

BT_PM 1.17 Describe the pharmacokinetics of intravenous opioids and their clinical applications

The high lipid solubility of fentanyl confers a long duration of action when given intrathecally  TRUE/FALSE

The rapid speed on onset of alfentanil is primarily due to its low pKa  TRUE/FALSE

Duration of action of remifentanil is determined by its elimination half life   TRUE/FALSE

The terminal elimination half life of morphine and fentanyl is similar   TRUE/FALSE

Active metabolites of both morphine and pethidine contribute to the duration of analgesic effect   TRUE/FALSE

Well done today: there are worse things you could be doing

A late post today, so that I could send a huge CONGRATULATIONS to all of you who sat the ANZCA Primary written paper today! I hope that it went well for all of you and that you were able to display your accumulated knowledge to your best advantage.

Remember it is normal to dwell on those things that didn’t go well. Inevitably, there will be some questions that didn’t feel quite as great as the rest. No need to be particularly worried by this, as the SAQ mark is an average of your all your scores.

I was looking for uplifting pictures to add to this post, perhaps of a beautiful holiday location or some cute little baby animals, but when I googled “best photos of 2017”, the world was not portrayed as a very happy place. It reminded me, that even when in the midst of stressful times, related to exams, study or work, we are actually very privileged to have the opportunity to do the job that we do.

I did find an amazing photo (the one above) and the accompanying story of this small group of Nepalese bee keepers, who harvest a rare psychotropic honey from hives on those cliffs!!. As a person who has a significant fear of heights, this job looks like one of my worst nightmares!! The article is a bit political, but you might find the description of the effects of the honey quite entertaining in your post exam stupor ( you may recognise the feeling 😉 )

I hope that you all find time to look after yourselves and indulge in something nice over the next few day. Well done again….

BT_PM 1.3 Pre-emptive and preventive analgesia

Glass poppies Andy Paiko

 

A few weeks ago I ran a series of posts on this LO.

I ran out of steam before reaching the last of the bullet points. This was partly because the area has held so much hope from a theoretical mechanistic viewpoint but there is little strong scientific evidence to support benefit from particular clinical practice – how disappointing….

I thought it might be timely to revisit now, just before the written exam. I wish there were a rapidly acting pre-emptive analgesic, I could prescribe, to make tomorrow less painful for those of you about to sit. However, the best prescription, to make the day easier, is to have studied well and practised lots – which I am sure all of you who read this blog will have done. BEST WISHES!!

The latest edition of Acute Pain Management: Scientific Evidence has a section on this topic (I hope that link takes you there. If it doesn’t, the book is freely available here [see section 1.5]).

BT_PM 1.3  Describe the basic physiological mechanisms of pain including:

· Pre-emptive and preventive analgesia

Pre-emptive analgesia, by definition, must be given before a noxious stimulus occurs TRUE/FALSE

The aim of pre-emptive and preventive analgesia is to reduce sensitisation   TRUE/FALSE

The NMDA receptor plays an important role in central sensitisation  TRUE/FALSE

Peri-operative ketamine infusions may have a role in preventing the development of chronic post-surgical pain    TRUE/FALSE

Outcomes in this area have been muddied by fraudulent research   TRUE?FALSE

Medical Latin

We use Latin abbreviations all the time….. do you know the meanings of any of these terms?

 

T / F    PRN is the abbreviation for pro re nata which means “never actually given”

T / F    “stat” is short for statim which means “melodramatic”

T / F    “Q” (as in Q4H) is short for quaque, which means “every”

T / F    “PO” is the abbreviation for per os, meaning “through the mouth” – NOT “go away”

T / F    “TDS” (ter die sumendum) and “TID” (ter in die) are equally acceptable for “three times a day”

 

For those sitting the written exam on Tuesday – all the very best!!!

Ventilation / Perfusion (V/Q) Relationships

BT_PO 1.26 Discuss normal ventilation-perfusion matching

BT_PO 1.29 Discuss ventilation-perfusion inequalities, venous admixture and the effect on oxygenation and carbon dioxide elimination

 

T / F   the V/Q ratio at the apex of the upright lung is 3.3, because the apex receives most of the alveolar ventilation

T / F   in a conscious person lying on their left side, the left lung will receive more ventilation AND perfusion than the right lung

T / F   in an anaesthetised ventilated patient lying on their left side, the left lung will receive more ventilation AND perfusion than the right lung

T / F   atelectasis results in an increase in alveolar dead space, which can cause hypercapnoea

T / F   a decrease in cardiac output can decrease mixed venous PO2 – this will magnify the hypoxaemia produced by any alveolar shunt

Nitrous Oxide

BT_GS 1.27 Describe the pharmacology of nitrous oxide

 

T / F   nitrous oxide does not support combustion

T / F   nitrous oxide acts synergistically with volatile agents to produce anaesthesia

T / F   nitrous oxide does not cause any peripheral vasodilation

T / F   nitrous oxide acts on GABA receptors in the brain

T / F   nitrous oxide use is associated with post-operative MI

Serotonin Syndrome

BT_PO 1.102 Discuss the clinical features and management of serotonin syndrome

 

T / F   all serotonin receptors are ligand gated ion channels

T / F   tramadol, pethidine, fluoxetine, amphetamines and amitriptyline are all potentially serotonergic

T / F   monoamine oxidase inhibitors are not serotonergic

T / F   features of serotonin syndrome include: CNS excitation; hyperthermia; and hyper-reflexia

T / F   treatment is usually supportive, although cyproheptadine is a potential antidote

Humidification

BT_SQ 1.5 Describe basic physics applicable to anaesthesia, in particular:
…. principles of humidification and use of humidifiers ….

 

T / F   during quiet breathing, air reaching the carina is close to 37 degrees C and 100% relative humidity

T / F   at 37 degrees C, air can hold a maximum of 44 mg/L of water vapour

T / F   during expiration, water vapour condenses onto the airway mucosa

T / F   absolute humidity depends upon both the temperature and the atmospheric pressure

T / F   a HME can warm inspired gases to about 30 degrees C, but this takes about 20 minutes

Study tip : Capitalise on your freshness

Last week I hosted a webinar, through ANZCA, entitled “Tips for the Primary Exam”. For those of you who are registered with ANZCA, you can watch it via the College networks (it is a bit of a time investment, but the fast forward button is always available).

One of the other contributors to this blog, asked me whether there were any noteworthy points that could be highlighted here. A lot of what I discussed has already been touched in the previous study tips on this blog.

With the upcoming exam, there has been single, but significant change – the increase in reading time to 15 mins and the allowance for you to write on the question paper during that time. I discussed how to use this change to your best advantage in the webinar and that is the point I will focus on today.

The written portion of the exam is a real feat of endurance – 2.5hrs of MCQs in the morning, backed up with 2.5 hrs of writing the SAQs in the afternoon. Exhausting! None of us write for that long continuously these days. By the end of the afternoon, you will be very tired.

A the start of the SAQ paper however you will still be reasonably fresh – capitalise on your freshness in the 15 mins reading time:

1. Read the questions carefully – those that look like repeated questions may have had important changes made. The answer you have practised for the old question may not be able to be successfully transplanted into the new question

2. Highlight important words – this may include those important word changes, things you wish to define, anything that helps you ANSWER THE QUESTION

3. Jot down a couple of notes to help you structure your answer – your brain will be thinking quite well at this stage. If something great enters it, take 30 sec to write it down. This may be especially helpful for questions you plan to answer towards the end of the 2.5 hrs. To be able to refer back to your little notes, when your brain is fatigued, may provide that little spark that helps you through.

I suggest that you include “Reading Time” in any set of SAQs you practice (1 min per question). The more times you use that extra minute per question in practice, the more useful it is likely to be for you in the exam.

SS_PA 1.52 Pharmacokinetic differences in neonates and children compared with adults and the implications for anaesthesia

A little person I know had an anaesthetic last week having swallowed a curtain hook, probably a couple of months ago. He had not been very keen to eat solid food!!

SS_PA 1.52 Describe how the pharmacokinetics of drugs commonly used in anaesthesia in neonates and children differ from adults and the implications for anaesthesia

Water soluble drugs have a larger volume of distribution in neonates TRUE/FALSE

Drugs that depend on redistribution into fat compartments for their termination of action have longer durations of action in neonates    TRUE/FALSE

The absorption of oral drugs is more rapid in neonates compared with adults   TRUE/FALSE

The relationship between weight and drug elimination is linear in children  TRUE/FALSE

Remifentanil’s half life is unchanged in neonates    TRUE/FALSE