Anesthesia awareness

Anesthesia awareness, also referred to as accidental awareness during general anaesthesia (AAGA) or unintended intra-operative awareness, is a potential complication occurring during general anesthesia where the intended state of complete unconsciousness is not maintained throughout the whole procedure. It can occur either because of failure to deliver sufficient anesthetic medication to the patient's body, or because of individual patient factors that mean the patient is resistant to what would normally be an adequate dose of anesthetic medication.

Awareness occurs when patients have anesthesia that is inadequate to keep them unconscious during an operation. The incidence of this anesthesia complication is variable and seems to affect 0.2% to 0.4% of patients according to the surgical setting carried out. This variation reflects the surgical setting as well as the physiological state of the patient. Thus, the incidence is 0.2% in general surgery, about 0.4% during caesarean section, between 1 and 2% during cardiac surgery and between 10% and 40% for anesthesia of the traumatized. The majority of these do not feel pain although around one third did, in a range of experience from a sore throat due to the endotracheal tube, to traumatic pain at the incision site. The incidence is halved in the absence of neuro-muscular blockade. In this situation, the patient may feel the pain or pressure of surgery, hear conversation, experience air hunger, or have difficulty breathing. The patient may be unable to communicate any distress because they have been given a muscle relaxant; without this, they can move and the anesthesiologists are alerted and provide more anesthetic drugs to render the patient unconscious again. If anesthesia awareness does occur, about 42% feel the pain of the operation, 94% experience panic or anxiety, and 70% experience lasting symptoms which may be psychological and may be physical or neurological. The quoted incidences are controversial as many cases of "awareness" are open to interpretation. These usually involve feeling severe pain, clear recall of the conversations of the operating room staff or suffocation. Some patients undergo sedation for smaller procedures such as biopsies and colonoscopies and are told they will be asleep, although in fact they are getting a sedation that may allow some level of awareness as opposed to a general anesthetic.

In some cases post traumatic stress disorder (PTSD) may arise after intraoperative awareness, causing the patient to require counseling for an extended period. Sometimes neurological and brain injuries caused during the operation are wrongly diagnosed and described as PTSD.

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