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





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



BT_GS 1.59 TCI

BT_GS 1.59 Describe the pharmacological principles of and sources of error with target controlled infusion

I am sure you have all looked at this screen. Here are some questions to test your knowledge of these models.

TCI Interface.png

TRUE/FALSE Inaccurate drug delivery from the infusion pump contributes to 55% of the overall inaccuracy of a TCI infusion

TRUE/FALSE With most modern TCI algorithms actual plasma concentrations are within 20-30% of predicted concentrations 95% of the time

TRUE/FALSE The Marsh model uses age and weight to calculate the compartment size

TRUE/FALSE The Schnider model may calculate a negative lean body mass in very obese patients

TRUE/FALSE The most clinically reliable method is to target the effect site concentration observed at loss of consciousness.