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What is anesthesia awareness?

Anesthesia awareness is when a patient wakes up or moves while under anesthesia, during a surgical procedure. In this video, anesthesiologist Yael Varnado, MD, discusses this rare surgical issue, and how there is a spectrum of patient experiences.  

Awareness during anesthesia implies that during a period of intended general anesthesia, the brain is aroused by stimuli that are stored in memory for future explicit recall. It has an estimated incidence between 0.007-0.91. Thus, with over 20 million general anesthetics performed yearly in the United States, the occurrence can be striking. Consequently, in 2004, The Joint Commission issued an alert stating that anesthesia awareness is an "under-recognized and under-treated" problem in health care organizations. The incidence in trauma patients is even more alarming and has been shown to range from 11-43% in various studies.

When discussing and describing awareness, there are several important terms that require defining:

  • Consciousness describes a state in which a patient is able to process information from his or her surroundings.
  • Unconsciousness results from the interruption in cortical communication and loss of integration that is needed to process information from one’s surroundings.
  • General anesthesia is a drug-induced state that produces unconsciousness.
  • Perceptions while under anesthesia are most commonly auditory (sounds, conversations) and feelings of fear, helplessness, pain, anxiety, and paralysis. Less commonly, they include visual perception, memory of intubation, and feeling the operation without pain.
  • Memories are often described as explicit or implicit. Explicit memory, or recall, is the conscious recollection of stored memories, whereas implicit memory describes changes in performance or behavior that are produced by previous experiences but without any conscious recollection of those experiences
  • Amnesia is the absence of recall. Patients may follow commands as they are emerging from anesthesia or during “wake-up” testing (e.g. spinal surgery to test the integrity of nerves), but not have conscious recall (explicit memory).
  • “Awake paralysis” is a term used to describe errors in the administration of neuromuscular blocking agent resulting in paralysis of the unanesthetized or incompletely anesthetized patient.
Anesthesia awareness, also referred to as “intraoperative awareness,” is an extremely rare event. It occurs when a patient becomes conscious during surgery and subsequently recalls what happened. Anesthesia awareness occurs approximately 1 to 2 times per every 1,000 uses of general anesthesia.
In some high-risk surgeries, such as trauma, cardiac, emergency cesarean delivery, or in situations involving a patient whose condition is unstable, using the usual dose of anesthetic drugs could harm the patient. In these and other critical or emergency situations, there can be a greater risk of awareness because the patient cannot be put safely into a deeper anesthetic state.
The American Society of Anesthesiologists is committed to educating the public about anesthesia awareness and minimizing its occurrence. Awareness during surgery only applies to patients who are under general anesthesia and does not include:
  • The period of time just prior to the anesthetic completely taking effect or as the patient is emerging from anesthesia.
  • Sedatives administered during a local or regional anesthetic (such as a nerve block, spinal or epidural).
  • Sedation for dental procedures and colonoscopies.
Most patients do not experience any pain during awareness. However, it can be disturbing and some patients may need counseling following surgery to ease their anxiety. If you believe you have experienced awareness, please talk to your medical care team immediately.
Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)

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 everyday life causing sleep loss, nightmares, anxiety, panic attacks and post-traumatic stress syndrome.


 

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.