| Popis: |
Summary Awareness by the anaesthetized patient of intraoperative events can occur and is generally understood, rightly or wrongly, to imply inadequate anaesthesia. However, the possibility that a patient may be awake and capable of communicating during general anaesthesia, yet have no conscious recall of this in the postoperative period, is not always recognized, nor is the significance of this phenomenon fully understood. This state, conscious awareness with amnesia, is, by definition, not detectable in the postoperative period except possibly by sophisticated psychological testing or hypnosis. A technique is described (the isolated forearm technique) which enables states of awareness to be detected intraoperatively. Difficulties arise in understanding conscious awareness with amnesia since, in terms of general anaesthesia, it is debatable whether a patient can be conscious and anaesthetized at the same time, or whether these states are, by definition, mutually exclusive. This chapter highlights some of the problems surrounding the definitions of consciousness and anaesthesia, and discusses the reliability of conventional monitoring in assessing the adequacy of general anaesthesia. Clinical data are also presented which confirm the view that neither changes in blood pressure, heart rate, sweating nor tear production, taken individually or in aggregate, can reliably predict when a patient may be awake during certain general anaesthetic techniques. |
