One of the most stressful times in a person's life is when they find out that either they or a loved one need to have surgery. To add to the stress, you may have heard a lot about being awake during the operation. You read an article somewhere, or was it your Aunt Ida who told you that when she was having her women's surgery she remembers being awake and hearing the doctors' voices in the operating room talking about their golf games and the most popular restaurants.
All kidding aside, awareness under anesthesia where a patient is partially or fully awake (hopefully not!!) during general anesthesia (when you are supposed to be asleep); or recall, the memory of events which occurred during general anesthesia, have both been documented and are a very real concern to patients and anesthesiologists. Does this mean that when you or someone you love is to have an operation you should worry that you're going to be awake?!!
First, let's talk about what general anesthesia for surgery means. General anesthesia is administered to render a patient unconscious and pain-free for an operation. During the operation, the patient receives sedatives (drugs that calm you and put you to sleep), analgesics (drugs that take the pain away), and muscle relaxants (drugs that paralyze you). I know this sounds horrible, but for the sake of the surgery it is very desirable because it gives the surgeon easier access to generally inaccessible parts of the body. For the most part a balanced combination of the above drugs is used to achieve the state of "general anesthesia". General anesthesia is usually achieved by the administration of different inhaled gases and intravenous drugs, alone or in combination. The gases used most commonly are oxygen, nitrous oxide and agents called isoflurane, enflurane, halothane, desflurane and sevoflurane (these agents are both sedatives and analgesics). The intravenous drugs commonly used are drugs called the benzodiazepines which are sedatives or hypnotics (drugs such as Valium® are the prototype), and the narcotics which are analgesics (drugs such as morphine and Demerol® are common). These drugs aren't the only drugs that the anesthesiologist will use. There are many others and the anesthesiologist is highly specialized in the proper use of these drugs and in how they will affect different people. But there is no cookie-cutter method and as Mr. Rogers says, "Everybody is special" and must have their anesthetic tailored to their specific needs. Therefore, you must tell the anesthesiologist your specific medical history.
Now what are the chances that someone will have awareness or recall during an operation? The overall incidence is usually considered at between 0.2 - 1% of all non-obstetric and non-cardiac surgery. Higher risks of recall are seen during obstetrical procedures such as Caesarian sections (7 - 28%), major trauma (43%) and cardiac surgery (23%). So in general the incidence of these events occurring is pretty small; unless of course it happens to you, right?!! So why isn't the incidence 0%? Well as we all know there really aren't any certainties in life or in medicine. In theory, the anesthetic drugs should allow the patient to be "out" from the time they roll into the operating room to the time they wake up in the recovery area. But not everyone is the same, and everyone's medical, physical and social make-up are different. How one drug or action affects one person, may be different than on the next person.
Each drug used in the provision of anesthesia has side-effects, the most notable of which is low blood pressure. This fact must be considered when a patient receives their drugs for anesthesia. Multiple drugs in combination may cause severe drops in blood pressure. This is why the anesthesiologist must know how each of these drugs works and what effects it will have once given. Some patients may require very little medication to ensure unconsciousness while others will require much more. Sometimes medication may make the blood pressure too low and that requires intervention to raise it. This is the reason that the percentage of awareness is higher in obstetrics, trauma and cardiac surgery. Many times patients are either emergencies or are very sick with very low blood pressures to start off with. The anesthesiologist while trying to provide adequate anesthesia must also ensure that the blood pressure does not fall dangerously low. The anesthesiologist must assess what the patient's medical condition can tolerate and then administer anesthesia accordingly. The anesthesiologist cannot just give a fixed amount of medicine to everyone and walk away satisfied. There must be constant re-evaluation during the procedure to ensure the best possible outcome for the patient. Medicine and anesthesia are basically part art and part science. Part of the art is being able to integrate the science of anesthesia (medications and technology) into the patient's physiology. For the most part it works well.
It seems that over the past year or so if you picked up a magazine or watched TV this subject has been focused on extensively. There have also been claims of new devices that can be placed in the operating room by the anesthesiologist to ensure unconsciousness during an operation. This is anesthesia's "Holy Grail" and several techniques have been looked at over the years; but so far technology has not provided a definitive solution to this problem. Even though there are articles written in the lay press about these devices they have yet to be proven as accurate indicators of anesthesic depth and at this time can not be recommended as a gauge for the anesthesiologist to determine how much anesthesia is enough. Awareness and recall are possibilities during the surgical experience. The risk is relatively low, and should certainly not be the foremost thing on your mind prior to the procedure. The most important thing is to have an anesthesiologist at your side who is constantly vigilant of the patient.