Wachzustände während Allgemeinanästhesie Definition, Häufigkeit, klinische Relevanz, Ursachen, Vermeidung und medikolegale Aspekte

Zusammenfassung

Man unterscheidet verschiedene intraoperative Wachheitsstufen, wie explizit erinnerbare bewußte Wachheit und Erleben von Schmerz, explizit erinnerbare bewußte Wachheit ohne Schmerzerlebnis, bewußte Wachheit mit Amnesie, unbewußte Wachheit mit impliziter Erinnerung und keine Wachheit. Die explizit erinnerbare bewußte Wachheit mit Schmerzerleben wird auf<1:3000 Allgemeinanästhesien geschätzt. Die erinnerbare bewußte Wachheit ohne Schmerz wird in der Literatur mit 0,2–2% angegeben. Mit 7–72% weist die bewußte Wachheit mit Amnesie in Abhängigkeit von den verwendeten Anästhesieverfahren eine weit größere Streuung auf. Unbewußte Wachheit mit postoperativer impliziter Erinnerung wird ebenso aufgrund methodischer Schwierigkeiten recht unterschiedlich mit bis zu 80% angegeben. Postoperativ kann sich nach einer intraoperativen Wachepisode beim Patienten ein sog. posttraumatisches Streßsyndrom entwickeln. Ursachen intraoperativer Wachheit können sein: Fehlfunktion der Narkosegeräte, die flache Allgemeinanästhesie wie bei Sectio caesarea, der akuten Versorgung des polytraumatisierten Patienten, während herzchirurgischer Operation, Bronchoskopie und bei erschwerter Intubation. Narkoseverfahren wie die alleinige Kombination von Relaxans und Lachgas, die alleinige Verabreichung von Opioiden und/oder Benzodiazepinen sind mit einer besonders hohen Inzidenz intraoperativer Wachheitsfälle belastet. Grundlagen für die gerichtlichen Schritte sind ärztliche Behandlungsfehler oder die nicht vorliegende Aufklärung und Einwilligung des Patienten für ein solches Ereignis.

Abstract

The possibility that a patient during general anaesthesia is aware of the operation going on and aware of severe pain that might be remembered postoperatively must be very alarming to patients and anaesthetists alike. Furthermore, there is experimental evidence showing that conscious recall of intraoperative events is only the tip of an iceberg; it seems very probable that there is even a higher incidence of unconscious perception during general anaesthesia. Therefore, the following stages of intraoperative awareness must be distinguished: (1) conscious awareness with explicit recall and with severe pain; (2) conscious awareness with explicit recall but no complaints of pain; (3) conscious awareness without explicit recall and possible implicit recall; (4) subconscious awareness without explicit recall and possible implicit recall; (5) no awareness. The incidence of conscious awareness with explicit recall and severe pain has been estimated at less frequent than 1/3000 general anaesthetics. Conscious awareness with explicit recall but no complaints of pain has been reported in the literature with an incidence of 0.5–2%. With 7–72%, conscious awareness without explicit recall and possible implicit recall shows a very wide range of variation and its occurrence probably depends on the anaesthetic drugs used. Subconscious awareness with possible implicit recall has an incidence of up to 80%, but there are many methodological problems in demonstrating implicit memory of intraoperative events. Reports of intraoperative awareness do not come exclusively from cardiac surgery and obstetrics, but also from all other operative specialities. Postoperatively, patients who experienced intraoperative awareness may develop a so-called post-traumatic stress syndrome. Symptoms involve re-experiencing the event awake or in dreams, sleep disturbances, depression, avoidance of stimuli associated with the event. The probability of the development of the post-traumatic stress syndrome seems to coincide with the experience of severe pain. When a patient complains of intraoperative awareness postoperatively the anaesthesiologist should discuss the event frankly with the patient. When the symptoms of the post-traumatic stress syndrome persist a psychotherapy should follow. Causes for intraoperative awareness may be: equipment failure, too-light anaesthesia, e.g. for a caesarean section or for emergency surgery in severely injured or polytraumatized patients, during cardiac surgery, bronchoscopy or difficult intubation. There is interindividual variability in anaesthetic effect; for example, chronic drug or alcohol abuse or overweight may make increased anaesthetic doses necessary. They are at risk for intraoperative awareness. Some general anaesthetics or anaesthetic procedures, e.g. the combination of a relaxant and N₂O, opioid mono-anaesthetics, or opioids combined with benzodiazepines, seem to involve a higher risk of intraoperative awareness than do volatile anaesthetics. The bases of litigation are medical malpractice, breach of contract by the anaesthesiologist or lack of informed consent from the patient. Therefore, patients who are at risk of intraoperative awareness should be given detailed information on this special risk before the operation.