Target controlled infusion (TCI) devices are increasingly used in clinical practice. These devices unquestionably aid optimization of drug dosage. However, it still remains to be determined if they sufficiently address differences in pharmacological make up of individual patients. The algorithms guiding TCI pumps are based on pharmacological data obtained from a relatively small number of healthy volunteers, which are then extrapolated, on the basis of sophisticated pharmacokinetic and pharmacodynamic modeling, to predict plasma concentrations of the drug and its effect on general population. One has to realize the limitation of this approach: these models may be less accurate when applied to patients in extreme clinical conditions: in intensive care units, with a considerable loss of blood, severe hypothermia or temporary changes in the composition of plasma, e.g., hypoalbuminemia. In the future, data obtained under these "extreme" clinical circumstances, may be used to modify the dosage algorithms of propofol TCI systems to match the clinical scenario.