Limitations of TCI models

Limitations of Any Models

• Most pharmacokinetic models were developed in a small group of young, healthy, non-obese subjects
• Large inter-individual and intra-individual differences exist
• Plasma drug concentrations in any individual patient are unlikely to be identical to those predicted by the pharmacokinetic model but are generally within +/- 20%
• The system does not consider drug interaction or concurrent drug therapy
• Less accurate in patients with characteristics deviating from healthy young adults
  • Multimorbidity
  • Older patients
  • Obese patients
• Less accurate in extreme clinical conditions
  • Critically unwell patients
  • Hypovolaemia
  • Severe hypothermia
  • Metabolic disturbances

Why bother using TCI if it is not accurate?

• TCI pumps are a useful tool for titration to effect (clinical effect or the desired effect on the EEG as measured by a pEEG monitor)
• The reliance on the accuracy of proportional changes (e.g. increasing or decreasing 10%) to allow titration of the drug concentration to the clinical effects in individual patients is more important than the predicted or actual measured values
• TCI systems allow the determination of a relevant and effective decrement time so as to predict the offset of the drug

Join us in Week 6 to learn more about these special subsets of patients