There is much more to study and learn about prevention of anesthesia complications and how technology may improve the safety and outcome of anesthesia. Large trials have never shown that a specific hemodynamic monitoring technique improves outcome. In controlled situations, oximetry and capnography have demonstrated efficacy in early detection of events that could be harmful during anesthesia. The BIS monitor has been shown to affect early recovery outcomes and possibly be of value in decreasing long-term mortality. Through all the controversy one thing remains constant: the response to information coming from monitors depends solely on the person administering the anesthesia. Aids to practitioner vigilance probably can never be proved to possess independent benefit, but their role in improving practitioner performance cannot be argued.