ABSTRACT
This chapter discusses the intravenous induction agents. The 'standard anaesthetic technique' is to induce anaesthesia with a quick-acting intravenous agent. These are mostly short-acting and provide an immediate, deep plane of anaesthesia that will allow control of the airway to take place. The patient must then be kept asleep with either an infusion of intravenous agent or volatile gas. Typically anaesthesia occurs at brain concentration of 4.0–8.0 mcg/mL, with dose adjustments the same as the induction dose. Thiopentone has many drug interactions and is oxidised in the liver. These enzyme systems are quickly saturated, and after multiple doses the metabolism of thiopentone changes from first order to zero order kinetics. Etomidate suppresses the adrenal cortex and cortisone release. For this reason, many anaesthetists no longer use it for septic or shocked patients and those undergoing major surgery. Midazolam is the only one with a short enough duration of action to be realistically used as an induction agent.
