How to Prevent Waking Up During Surgery (3:12)
It is unfathomable to think that someone would go under the knife without some form of anesthesia. Ever since the mid-1800s when an enterprising dentist discovered that inhaling ether gas would knock a patient out well enough to painlessly extract a tooth, anesthesia has been indispensible. However, as you can imagine, the methods of that time were both imprecise and dangerous: If the patient inhaled too little ether they would wake, and if they inhaled too much they died.
Today, general anesthesia techniques are so advanced that surgeons can confidently operate knowing that patients will not move about, feel pain or remember anything from the moment they start counting backwards, to the time they regain consciousness in the recovery room.
Every year, millions of people go under the knife – and under general anesthesia. They remain completely asleep during the procedure and have zero awareness of the event.
But not always.
Sometimes general anesthesia is administered and the surgery begins, but the patient isn't completely "under." Like something straight out of the "Twilight Zone," people hear conversations, feel the surgeon manipulating their bodies, even smell the cauterizing of flesh, but they are unable to let anyone know.
This rare phenomenon of being consciously alert but physically paralyzed is called unintentional intraoperative awareness or anesthesia awareness, and its effects can bring about a lifetime of mental anguish. Remembrances can intrude into every day life causing sleep loss, nightmares, anxiety, panic attacks and post-traumatic stress syndrome.
There are 3 types of anesthesia: local, regional and general. While there may be some intentional awareness with regional or local anesthesia, the goal of general anesthesia is to not only keep patients still and pain-free, but also to keep them from being aware of what happens throughout the procedure and certainly from recalling it later on.
To achieve this, anesthesiologists use a combination of intravenous drugs and inhaled gases to block muscle activity, pain signals and memory of the event. The exact cocktail depends on how long the patient needs to be asleep, the type of procedure being performed and the overall condition of the patient including their physical attributes and health.
After the anesthesia is administered, electronic devices continually monitor and regulate breathing, oxygen, carbon dioxide, heart rate, body temperature and blood pressure. All the while, the anesthesiologist can make adjustments as needed.
An active brain however is particularly difficult to monitor. Doctors might suspect that consciousness isn't fully dampened when they see signs such as a elevated blood pressure or heart rate, or muscle movement. But certain drugs used to achieve anesthesia may mask these changes. Some hospitals use the bispectral index (BIS) brain-sensing monitor, similar to an electroencephalogram (EEG), to measure a patient's level of consciousness. But not all hospitals use this monitoring method and some doctors dispute their value in signaling or preventing anesthesia awareness.