BT_GS 1.53 Describe the synergism between anaesthetic agents, opioids and regional blockade and how this is used clinically

TRUE/FALSE  Moderate doses of opioids can reduce MAC of volatile agents by as much as 75%.

TRUE/FALSE  50% reduction in doses is expected when propofol and midazolam are used together for hypnosis.

TRUE/FALSE  The exact degree of drug synergism can be calculated from pharmacokinetic data of individual agents.

TRUE/FALSE  The bispectral index is additive when propofol and remifentanil are used in total intravenous anaesthesia.

TRUE/FALSE  Midazolam has no effect on the ketamine dose required to suppress movement to a noxious stimulus.

Paediatric Pharmacokinetics

Paediatrics.png

SS_PA 1.51  : Describe how the pharmacokinetics of drugs commonly used in anaesthesia in neonates and children differ from adults and the implications for anaesthesia

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

TRUE/FALSE The half life of drugs is longer in 2 year olds than in neonates

TRUE/FALSE The FA/Fi curves in infants is steeper than in adults

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

TRUE/FALSEPlasma protein binding in neonates varies both qualitatively and quantitatively

Another cool book that should be on the ‘Recommended Texts for the Primary’ list

9781905237166-us

Most people don’t find pharmacokinetics particularly palatable. This book is arguably one of the most enjoyable ways you can learn about pharmacokinetics. This book doesn’t just entertain but it also gives you a sound understanding of PK concepts as they relate to the practising anaesthetist. It is under 200 pages and can be read in a day. It is fairly non PC which accounts for half its charm. Nothing in there about TCI sadly.

Addendum by woundedwildebeest… I got to see this post when it was a draft and bought the book. I definitely second this recommendation. Funny, educational, with even a dramatic twist on the last page. I’d suggest reading a chapter at a time and applying it in theatre before moving on to the next.

BT_GS 1.59 Describe the pharmacological principles and sources of error with TCI

kindle cover2504Many of us use TCI on a daily basis. Indeed some people use it almost exclusively. Fewer appreciate the remarkably small data set that the algorithms were created from. Even fewer understand the limitations of the algorithms. If you want to find the answers to the statements below can I suggest you look at the chapter “Everything you should know about Propofol TCI” in the book The First Year. It can be freely downloaded from the College Library: click on Library Guides> Medical Education> Featured Resources and scroll to the bottom. The pdf is waiting for you. The cover is reproduced above. The TCI pump algorithms are poorly treated in the texts.

Q. A TCI using the Marsh algorithm will give the same dose of propofol to an eighty year old and a twenty year old patient of the same weight.  TRUE/ FALSE

Q. TCI can be used for morbidly obese patients.  TRUE/ FALSE

Q. The Minto algorithm for Remifentanil was devised by an Australian anaesthetist.  TRUE/ FALSE

Q. Plasma or effect site TCI can be used effectively for the Schnider algorithm.

Q. The James equations are used to calculate LBM in the Minto and Schnider algorithms.  TRUE/ FALSE

 

 

 

 

BT_GS 1.12 Explain and describe clinical application of concepts relating to intravenous and infusion kinetics

The joys of pharmacokinetics are relatively few but a sound understanding of PK principles is a necessary evil for the anaesthetist. The following statements relate to the ubiquitous PK parameter, keo.

Q. Is the rate constant that describes transfer of drug from the central compartment to the effect site.  TRUE/ FALSE

Q. Is the rate constant for elimination of drug from the effect site.  TRUE/ FALSE

Q. Is directly proportional to the t1/2keo.  TRUE/ FALSE

Q. Can be measured directly using frequent blood sampling.  TRUE/ FALSE

Q. Has units of inverse time.  TRUE/ FALSE

 

2017.1 : SAQ 3

Propofol and remifentanil target controlled infusions are often given together as a total intravenous anaesthesia technique. Discuss pharmacological reasons why this is a useful combination.

BT_GS 1.59    BT_GS 1.53    BT_GS 1.41

A practical pharmacology question on a common drug combination. Before setting out to write a model answer try asking yourself first what are the clinical reasons you use this combination.

There are significant pharmacokinetic interactions between these drugs  TRUE/FALSE

There are significant pharmacodynamic interactions between these drugs  TRUE/FALSE

Both drugs have a rapid offset  TRUE/FALSE

Adding remifentanil to propofol can lead to more stable haemodynamics  TRUE/FALSE

Can be used in patients susceptible to malignant hyperthermia  TRUE/FALSE

 

 

SS_PA 1.51 : paediatric pharmacokinetics

As promised…

SS_PA 1.51  : Describe how the pharmacokinetics of drugs commonly used in anaesthesia in neonates and children differ from adults and the implications for anaesthesia

Neonates require larger doses of neuromuscular blockers per kg than adults   TRUE/FALSE

Neonates require larger doses of remifentanil per kg than adults   TRUE/FALSE

Neonates require a larger induction dose of thiopentone per kg than adults   TRUE/FALSE

Higher doses of EMLA can be more safely used in neonates than older children   TRUE/FALSE

Surgical stress decreases the concentration of alpha 1 acid glycoprotein   TRUE/FALSE

BT_GS 1.3& 1. Dose-effect curves and related terms

Clearly a favourite of mine (see yesterday’s post and also this one)

BT_GS 1.3 Define and explain dose-effect relationships of drugs with reference to:

· Graded and quantal response

· Therapeutic index

· Potency and efficacy

· Competitive and non-competitive antagonists

· Partial agonists, mixed agonist-antagonists and inverse agonists

· Additive and synergistic effects of drug combinations

BT_GS 1.4 Describe efficacy and potency with reference to dose- response curves

Use the curve below as a basis for your graphs

sigmoid curve

1.Add axes to indicate that the curve is a graded dose-response curve for a full agonist. Show the ED50.

2.Draw on the same axes, the same agonist in the presence of a competitive antagonist. Indicate the important features on your curve.

3.Show a partial agonist (E=0.8) which is equipotent to the full agonist drawn

4.Show on the graph with the full agonist, a more potent partial agonist capable of producing 50% maximal effect

5.Are any of the curves 2-4 compatible with a graph representing the full agonist in the presence of a non competitive (irreversible) antagonist? If so, which one?

I’ll post the answers later in the week

 

BT_GS 1.3 Dose response curves and associated terms

This is one of my favourite topics to ask in vivas. It is very easy to get yourself confused unless you have things clear in your head. Practise, practise, practise…..

BT_ GS 1.3 Define and explain dose-effect relationships of drugs with reference to:
· Graded and quantal response

· Therapeutic index

· Potency and efficacy

· Competitive and non-competitive antagonists

· Partial agonists, mixed agonist-antagonists and inverse agonists

· Additive and synergistic effects of drug combinations

 

Antagonist drugs have no intrinsic activity TRUE/FALSE

Quantal dose response curves look at the response of an individual to varying doses of a drug TRUE/FALSE

Therapeutic index is derived from quantal dose response curves TRUE/FALSE

Potency of a drug can be deduced from both a graded and quantal dose response curve TRUE/FALSE

A competitive antagonist will reduce the maximum efficacy of the agonist drug 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