Computer controlled pharmacokinetic models
Using a pharmacokinetic model, a computer continuously calculates the patient’s expected drug concentration and administers a BET regimen, adjusting pump infusion rates, typically at 10-second intervals. Models are derived from previously performed population pharmacokinetic studies. By programming desired target concentrations, the anaesthetist uses the device in a fashion analogous to a vaporizer. There are differences between predicted and actual concentrations, but these are not of great consequence, provided the true concentrations are within the drug’s therapeutic window.
Patient pharmacokinetics and pharmacodynamics vary with age, cardiac output, coexisting disease, concurrent drug administration, body temperature and weight of patient. These factors play an important role in choosing target concentrations.
Vaughan Tucker developed the first computer assisted total IV anaesthetic system [CATIA]. The first commercial target-controlled infusion device was the Diprufusor introduced by Astra Zeneca, dedicated to propofol administration in the presence of a pre-filled propofol syringe with a magnetic strip at its flange. Many new systems are available for use now. Patient data like weight, age and height are programmed in the pump and the pump software, by using pharmacokinetic simulation, apart from administering and maintaining appropriate infusion rates, displays the concentrations calculated and the expected time to recovery.
Post time: Dec-10-2024