Predicted effect compartment concentration of thiopental at loss of eyelash reflex

We derived the predicted effect compartment concentration ofthiopental, at loss of the eyelash reflex, following three differentinjection regimens. Sixty patients were given thiopental forinduction of anaesthesia. Twenty patients received multiplesmall boluses, 20 patients received a single bolus and 20 patientsreceived an infusion. Computer simulation was then used to derivethe effect compartment concentration. The median concentrationwas not significantly different between the three groups. EC₅₀,derived after combining all three groups was 11.3 µg ml^–1.The EC₀₅–EC₉₅ range was 6.9–18.3 µg ml^–1,suggesting wide inter-individual variation. Br J Anaesth 2001; 86: 422–4