Anesthesia Awareness—What If I Am Awake During Surgery?
Anesthesia Awareness - Awake Under Anesthesia
Fear of being awake under anesthesia, called anesthesia awareness or intraoperative awareness, causes a lot of anxiety for patients facing surgery.
Having anesthesia is scary for most people. As an anesthesiologist, I usually meet patients right before their surgeries. People facing surgery have many apprehensions and fears. More and more are concerned about anesthesia awareness.
I repeatedly hear that patients are often more apprehensive about the anesthesia than the surgery itself. And of all the fears that people have about the anesthetic side effects and anesthetic complications, the one I hear most often is, "I'm afraid of waking up during the surgery."
Anesthesia awareness has received a great deal of attention in the press over the last few years and even a full-length movie, called "Awake," capitalized on this fearful concept (I have reluctantly included the trailer here). But what is it really? Why and to whom does it occur? Keep reading to find out why it most likely won't happen to you.
"Awake" - Sensationalizing Anesthesia Awareness
What Is Anesthesia Awareness?
Anesthesia awareness, also called intraoperative awareness refers to a specific situation where a person is under general anesthesia for surgery and regains consciousness during the surgical procedure.
The definition of general anesthesia includes induction and maintenance of loss of consciousness. This means that you should not be able to wake up until the surgery is over. You do not respond to voice or painful stimuli.
For various reasons, some people do regain consciousness when they are under general anesthesia. For most people, this involves a very brief, hazy memory. Some people are aware of what is being said, but cannot move or indicate that they are awake. Still, there is usually no sensation of pain or awareness of the operation. The very rare, unfortunate few are awake, cannot move and do feel the surgery being done.
What Is NOT True Anesthesia Awareness?
There are many situations that are confused with anesthesia awareness.
Sedation anesthesia. I often have patients tell me they had anesthesia awareness during their colonoscopy or other procedure. These procedures are commonly done under intravenous sedation anesthesia. While the intravenous sedation drugs do cause sleepiness and often amnesia- you don't remember the procedure, they do not cause unconsciousness. It is not at all abnormal to be awake and remember these procedures. With the sedation, pain medications are either injected at the surgical site or given in the IV or both. You should still not be uncomfortable, even if you are awake, during surgeries or procedures under sedation.
Sedation plus spinal or epidural. Neither sedation or spinal/epidural anesthesia makes you unconscious during your operation. If you have spinal or epidural anesthesia to block the pain of surgery, you are usually also given sedation. The same is true for local anesthesia as well. In this case, it is not unusual or abnormal to have memories of being in the operating room. This is not anesthetic awareness.
Dreaming. Some people actually dream during their anesthetic, or more likely, when transitioning from unconsciousness back to wakefulness at the end of surgery. These dreams are often interpreted as actual wakefulness, but are not.
Waking at the end of surgery, but not able to move. When you return to consciousness, sometimes your brain is more awake than your body. You are waking up, but cannot move for a couple minutes. You can hear the anesthesiologist talking to you or feel the nurses putting bandages on your incisions, but cannot yet respond. The anesthesia wears off at different rates for different people. If your surgery is over, but you are still in the operating room and have memories of this, it is a normal variant of the emergence phase from anesthesia. Most people are conscious when they leave the operating room, post anesthesia, and many are talking and asking questions, but may not remember it later. If you do remember this phase, it's ok. The same is true for the beginning of your anesthetic, the anesthesia induction. Vague, hazy memories of being in the operating room are confusing and can be mistaken for being awake during the anesthetic.
Video from the American Society of Anesthesiologists explaining Awareness
Risk Factors for Intraoperative Awareness
Certain risk factors make anesthesia awareness more likely.
Type of surgery and type of anesthesia. Certain types of surgery are associated with higher incidences of anesthesia awareness. Surgeries where using lower concentrations and amounts of anesthetics is necessary to protect patients lead to more intraoperative awareness. Emergency cesarean sections, trauma surgeries, and open heart surgeries are the most likely cases to be associated with anesthesia awareness. Anesthesia challenges the body's physiology. Heart rates vary and blood pressures drop. When they cannot be adequately managed by giving more medication, the anesthetic must be "lightened" in order to NOT endanger the patients' lives.
There are certain brain and spinal cord surgeries that require that no anesthesia gas be used in order to not interfere with the nerve monitoring being used to prevent paralysis. The anesthetic called TIVA (total intra-venous anesthesia) also predisposes to higher rates of anesthesia awareness.
Type of patient. Patients who use illegal drugs such as cocaine and methamphetamine may be more likely to have intraoperative awareness. Not only do these drugs cause dangerous fluctuations in heart rate and blood pressure, they make the metabolism of anesthetic drugs much more unpredictable.
Some prescription medications. Certain prescription medications may also increase the risk. Anesthetics are adjusted throughout the surgery based on surgical stimulation level, type of anesthesia and the heart rate, breathing rate and blood pressure of the patient. Patients who take medications that block the normal increases in heart rate or blood pressure may have their signs of light anesthesia masked by the medication.
Statistics on Awareness Under Anesthesia
The American Society of Anesthesiologists estimates that some degree of anesthesia awareness occurs in about 1 in 1000 general anesthetics. It is believed that the majority of these cases are during the induction (beginning) of the anesthetic when the drugs haven't fully taken effect. Likewise, a great many cases are at the end of surgery, during anesthetic emergence, when the anesthetic is wearing off but isn't completely gone. These are not intraoperative awareness as the surgery is not occurring. Because the memories are fuzzy and confusing, patients often don't know that this wasn't during the surgery itself.
There are no exact statistics on true intraoperative awareness cases that occur during the surgery and cause distress and lasting trauma to the patient. It is, however, an area of active study and research.
Again, talk to your doctors and ask questions if you are remotely concerned that this has happened to you.
Prevention: What You Can Do to Prevent Intraoperative Awareness.
Talk to your anesthesia doctor and provide accurate information. This is your best defense against intraoperative awareness.
So, be honest with your doctor about:
- Your fears. Usually, this will help calm you. While no absolute guarantees can ever be made, your doctor can help pinpoint whether or not you have higher risk than average for this complication and let you know how he or she will address the risk.
- Alcohol consumption. Chronic, excessive alcohol intake results in a higher need for anesthetic medications.
- Illegal drugs use. Your anesthesiologist needs to know this to figure out which and how much anesthesia it will take to get you to sleep and keep you there. They are not there to judge you, but cannot keep you safe if they don't have all relevant information.
- All of your prescriptions and supplements. Different medications affect the metabolism of anesthesia differently. And just because supplements are "natural" or "alternative" doesn't mean they don't have side-effects or don't interfere with anesthetic medicines.
How the Anesthesiologist Monitors During Surgery
The anesthesiologist, using intraoperative monitoring, will be watching your heart rate, blood pressure, and breathing rate (if a ventilator doesn't need to be used). Increases in these seen on the intraop monitors indicates that the anesthesia is too "light." These parameters generally increase before any awareness occurs. The anesthesiologist is constantly adjusting the delivery of the anesthesia gas and giving other medication in the IV to keep the anesthesia level where it needs to be. The anesthesia is increased to ensure adequate depth of anesthesia if it's too light. Likewise, even though you are unconscious, your body will reflexively move to stimulation if the anesthetic depth needs to be increased. This also occurs before awareness.
The various brain monitors on the market have not been shown to reduce anesthesia awareness, despite what the makers of these expensive devices say. They do provide other useful information and may or may not be used if your hospital has them, at the discretion of the anesthesiologist.
A study published in the "New England Journal of Medicine" (August 18, 2011) has actually shown that relying on a BIS (brain) monitor can actually increase the incidence of intraoperative awareness vs. using measurement of the anesthetic concentration (the usual technique). This sounds counter-intuitive, but to me is not surprising. Here's why...
The BIS monitor (which I use for other information) gives a number that is indicates the level of consciousness. Other indicators include heart rate, blood pressure and breathing rate/pattern changes (if the patient is breathing on their own). In my experience (disclaimer-based on only my experience, not scientific study), the changes in vital signs happen first. Heart rate goes up before you see a change in the BIS number. That means that providers who rely only on the BIS number and ignore the changes in vital signs may be missing the chance to prevent awareness. The awareness may have already happened before the change in BIS number is seen. There is a lag between the event and the change in BIS.
Personally, I try to use all the data available to me and not rely on the BIS monitor for prevention of awareness. Vital signs to me are more reliable, happen earlier (before awareness can occur in most cases) and should not be ignored to focus on the BIS monitor. The BIS does provide other useful info, but is not as reliable as the manufacturer may claim to prevent awareness.
Treatment for Anesthesia Awareness
If you have had a case of genuine intraoperative awareness, let your doctor, surgeon, or anesthesiologist know right away. Many people do well with just an explanation of why it might have happened. Others suffer short-term or even long-term post-traumatic stress disorder. In those cases, an evaluation by a psychologist or psychiatrist and possible medications may be needed, usually on a short-term basis.
If you aren't sure if you had true anesthesia awareness, speak to your surgeon or contact the anesthesiologist. Most people who aren't sure have had one of the other experiences -- like sedation, dreaming, or waking at the end and being confused about the time -- and feel much better after having their questions answered.