Intraoperative alertness

Anesthesia awareness (Engl. Awareness ) is present when a patient during general anesthesia (anesthesia) perceives its environment partially or completely or actively follow prompts. Intraoperative states of wakefulness without memory are differentiated from those with unconscious (implicit) and conscious (explicit) memory in retrospect, with most of those affected belonging to the first group.

If there are no particular risks, waking phenomena occur at a frequency of one to two cases per 1,000 anesthesia (0.1 to 0.2%). However, in children, the risk of such an event is increased by 8-10 times. Another study found a frequency of 1: 15,000, provided that the patients are not specifically questioned, i.e. only about every 30th patient independently reports an awareness they have experienced. There is an increased risk in emergency interventions , caesarean sections , cardiac surgery , interventions at night, seriously ill patients with limited cardiovascular reserves ( ASA status IV, V), drug addiction, patients with chronic pain, previous episodes of intraoperative wakefulness, the use of muscle relaxants , total intravenous anesthesia and no premedication with a benzodiazepine .

Monitoring system for EEG monitoring ( BIS )

The experience of awareness is very variable and can include hearing and visual perceptions and the sensation of pain , paralysis , helplessness and fear . The convalescence after surgery can significantly be impaired ( posttraumatic stress disorder ), usually an experience of intraoperative awareness is not associated with longer-term consequences. In individual cases, a post- traumatic stress disorder that requires treatment can develop . This can also be caused by states of wakefulness without conscious memory.

Measures to avoid awareness include the identification of risk factors before an intervention, a standardized test of the equipment, the clinical monitoring of the patient (heart rate, blood pressure, pupil size, sweating, movements of the patient). The depth of anesthesia can be checked using monitors based on the recording of an electroencephalogram (EEG). The use of these devices is controversial, as there is no convincing data that the frequency of awareness can be significantly reduced. The American Society of Anesthesiologists does not recommend regular use for this reason. Another possibility is the regular demand to move a hand that is not affected by the anesthesia ("isolated forearm technique").

Classification according to Jones

JG. Jones (1994) classifies the degree of intraoperative alertness as follows:

• 1 ° Explicitly rememberable, conscious wakefulness with experience of pain
• 2 ° Explicitly rememberable, conscious wakefulness without experiencing pain
• 3 ° conscious wakefulness (simple conscious activities are possible, e.g. following prompts) without conscious, but with possible subconscious memory
• 4 ° Unconscious wakefulness, with amnesia of explicit (conscious) memory, but unconscious (implicit) memory
• 5 ° No alertness

literature

• I. Rundshagen: Intraoperative alertness. In: Anästh Intensivmed. 2009; 50, pp. 296-308. Review.
• U. Linstedt, H. Wulf: EEG measurement to avoid awareness - benefit or luxury? In: Anasthesiol Intensivmed Emergency Med Schmerzther. 2008 May; 43 (5), pp. 384-391. PMID 18464217
• American Society of Anesthesiologists Task Force on Intraoperative Awareness: Practice advisory for intraoperative awareness and brain function monitoring: a report by the American society of anesthesiologists task force on intraoperative awareness. Anesthesiology. 2006 Apr; 104 (4), pp. 847-864. Review. PMID 16571982
• BA Orser, CD Mazer, AJ Baker: Awareness during anesthesia. In: CMAJ. 2008 Jan 15; 178 (2), pp. 185-188. Review. PMID 18073268
• Stefanie Pilge, Gerhard Schneider: Awareness - Clinical Relevance Awareness - clinical relevance. Georg Thieme Verlag Stuttgart · New York, Anästhesiol Intensivmed Emergency Med Schmerzther 2013; 48 (1): 48-56 doi : 10.1055 / s-0032-1333079
• George A. Mashour, Beverley A. Orser, Michael S. Avidan: Intraoperative Awareness. From Neurobiology to Clinical Practice. Anesthesiology, May 2011, V 114, No 5, pp. 1218-1233
• Peter Samuelsson: Awareness and Dreaming during Anesthesia. Incidence and Importance. Dissertation, Linköping University Medical Dissertations No. 1082, Linköping and Kalmar 2008
• George A. Mashour: Consciousness, Awareness, and Anesthesia. Cambridge University Press, 2010, ISBN 1-13948-637-3
• R. Sandin: Outcomes after awareness with explicit recall. Acta Anaesthesiologica Belgica 57 (2006) (4): 429-432.

Web links

• J. Wallenborn: Neuromonitoring in Anesthesia - What is important? AI-online, (2014), pp. 33–49

Individual evidence

1. ↑ Unwanted wakefulness during anesthesia. In: Dtsch Arztebl Int. 2011; 108 (1-2), pp. 1-7. doi: 10.3238 / arztebl.2011.0001
2. ↑ JJ Pandit et al .: A national survey of anesthetists (NAP5 Baseline) to estimate an annual incidence of accidental awareness during general anesthesia in the UK. In: Anaesthesia. Volume 68, pp. 343-353, April 2013. doi: 10.1111 / anae.12190
3. ↑ Marieke Degen : Psychology - Awake in general anesthesia (archive). In: deutschlandfunk.de. December 5, 2013, accessed April 12, 2015 . 
4. ↑ JG. Jones: Perception and memory during general anesthesia. Br J Anaesthesia (1994) 73: 31-7

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