The media has certainly done its part to get people thinking about intraoperative awareness.  From multiple late night news reports, to the movie, "Awake", patients' preoperative anxiety levels have risen noticeably.  This issue is without doubt, one of the more common concerns expressed to us by patients before their operations and as such deserves a thorough explanation.

"Awareness" refers to some type of recall of an event or experience under general anesthesia.  If regional anesthesia or conscious sedation is the anesthetic of choice, then occasional episodes of awareness may be normal and certainly not associated with any pain or discomfort.  General anesthesia, however, implies a state of unconsciousness for the duration of the operation. Aside from the events related to actually going to sleep and waking up, the intraoperative experience should be recall-free.

So how worried should you be about awareness under anesthesia?  The answer is: not much at all.  The incidence of intraoperative awareness has been reported to be about 0.1% or 1 in 1000. This figure is somewhat misleading because it is primarily composed of high risk scenarios such as trauma surgeries, emergency caesarian sections and open heart surgeries.  In such cases, deep anesthesia may be unsafe to administer due to the fragile state of the patient.  For the typical patient who is not at high risk, the incidence of awareness is closer to 1 in 40,000 cases or 0.0025%.
How do we keep the numbers so low? By keeping a very close eye on you. We use a host of sophisticated devices to monitor your vital signs, anesthesia levels and if deemed appropriate, your level of consciousness. This last type of monitor, the level of consciousness monitor, attempts to quantify the degree of wakefulness using EEG waves. The most common level of consciousness monitor is called the BIS monitor. As of yet, this technology has not yet been proven to minimize the likelihood of awareness. A study in The New England Journal of Medicine (March 2008) concluded by stating, "...our findings do not support routine BIS monitoring as part of standard practice." The bottom line is that there is no substitute for the undivided attention of a caring and experienced anesthesia professional.
Still worried?  If so, here's what you should do:
  • Talk to your anesthesiologist about your concerns and apprehensions.  
  • Discuss previous anesthetic experiences.  
  • Be frank about drug usage, prescription or otherwise.
  • Visit the American Society of Anesthesiologists website at and click on Patient Education for more information. 
What you should not do, is delay a needed surgery for fear of this exceedingly rare event.

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