How common is anesthesia awareness

The procedure was successful - at least from the doctors' point of view. It is not known exactly how the patient coped with the operation. The 20-year-old consumptive book printer Gilbert Abbott is considered to be the first sick person to be given general anesthesia. On October 16, 1846, the dentist William Morton at the Massachusetts General Hospital in Boston had him inhale ether - and Abbott fell into a twilight sleep.

The chief surgeon, John Collins Warren, performed the procedure himself and removed a cyst on the patient's neck in front of an audience in the classroom. However, towards the end of the five-minute operation, Abbott stirred and made unclear noises. He then reported that although he was pain-free during the procedure, he had heard noises and "indistinctly heard the scraping of a knife".

Since its inception, anesthesia has struggled with waking patients up while anesthetized and remembering gruesome details long afterwards. This is by no means just a problem from the pioneering days of the discipline, when depth of anesthesia was often a matter of luck and some patients suffered agony from being given too little anesthetic while others were given too much and never regained consciousness.

Even today, up to 16,000 patients a year in Germany are awake during general anesthesia, for short phases or for a longer period of time. In extreme cases, they experience the entire operation with full consciousness - without being able to move, speak or otherwise express themselves.

"This is one of the worst fears of patients and hits a primal fear," says Martin Sack, senior physician for psychosomatics at the TU Munich and chairman of the German Society for Psychotraumatology. "You definitely don't want to experience that." With the anesthetist Gerhard Schneider, Sack has written a book about undesirable intraoperative alertness - it deals with perceptions during anesthesia and possible consequences of awake phases on the psyche, which may require trauma therapy.

The problem has been known to doctors for a long time. In the 1970s and 1980s, anesthesiologists assumed that one percent of patients had awake moments while under anesthesia during surgery. In relation to around eight million operations under general anesthesia in Germany alone, this would mean that up to 80,000 patients did not continuously fall into the unconscious twilight sleep during the anesthesia, which should guarantee them freedom from pain.

Every year 500 people are traumatized after an operation

In the meantime, current studies from Scandinavia, Australia and the USA have shown that "only" 0.1 to 0.2 percent of patients experience the waking phenomena that doctors call awareness. Anesthetics were constantly being improved and dosages refined. Anesthetists know about the risk of light anesthetics and certain narcotics.

But it is not easy for the anesthetist to recognize phases of wakefulness during the operation. The patient may move their toes a little, the anesthesia is a little flatter and the anesthetist doses the anesthetic. But what is the patient just seeing? Doctors are advised to closely monitor anesthetic gas concentration and EEG to prevent the anesthetized from feeling anything. However, there is no generally recognized unit of measurement for the depth of anesthesia or even normal values. Blood pressure, heart rate and sweating show only imprecisely whether patients feel no pain, their muscles are no longer tense and how high the level of their loss of consciousness is.

Children seem to be twice as likely as adults to be awake during surgery, which is due to the fact that drugs redistribute faster in their bodies and a constant concentration is therefore more difficult to achieve. In emergency operations, night-time surgery and deliveries by caesarean section, unwanted alertness is statistically more common, because in all three cases an insufficient dose of anesthetic is chosen.