RETURNS THU JAN 19 8|7c

Anesthesia Awareness

By Meg Marinis, Director of Research | Feb 4th, 2010
Absolute terror.

That's what Meredith saw in Leslie Wilson's eyes when she realized that the patient had woken up during her surgery in the OR. Leslie recounts the horror of being able to smell her own "burning flesh," not being able to speak, not being able to move—it was like being alive in a coffin. We understand why she might not want to have Bailey's hands touch her again...

Anesthesia awareness is the unintentional consciousness or awareness of events happening during an operation either with, or without pain sensations. The patient might not be able to physically notify any member of the operating team, but he or she might be able to hear conversations or surgical equipment.

Why do people wake up during surgery? Why did Leslie wake up in Bailey's OR tonight?

During some procedures, the team of medical professionals may choose to administer less anesthesia to the patient due to the nature of the surgery. They make a calculated decision based on the patient's general health, medical history, and current problem. For example, if a patient seems to be having severe respiratory problems, the team may choose to lighten the anesthesia dose.

Also, people react to medications differently; it involves the patient's drug metabolism. Drug metabolism is the process where the body breaks down medication and converts it to active chemical substances, through the use of enzymes (also manufactured within the body). Though many tissues in the body can metabolize substances, most metabolic activity occurs in the liver.

In Episode 613, we introduce anesthesiologist Dr. Ben Warren. After the incident in Bailey's OR, Ben runs a work-up on patient Leslie Wilson and determines that her body metabolizes anesthetic agents much more quickly than most people. He returns to tell Bailey about Leslie's "cytochrome P450 results." Cytochrome P450 (also known as CYP450) is a large group of enzymes found in the body that breaks down compounds (which include drugs and toxic compounds in the liver). After discovering the make-up of Leslie's enzymes, Ben now knows he needs to adjust the dosage of anesthesia (increase it most likely) given to her during surgery. However, due to ongoing research on this theory, studies are still being done to determine an efficient way of testing patients' rate of drug metabolism.

What are the consequences of awareness during surgery?

Obviously, it depends on the patient who experiences awareness. Some people may feel no adverse effects. However, on the other end of the spectrum, some patients feel such anxiety after the event that they may be even diagnosed with post-traumatic stress disorder. These feelings may last from a few days to years, but, in either instance, if a patient endures such a trauma, he or she should talk to a health provider.

But! How often does anesthesia awareness occur?

RARELY. Patients should feel assured that they will remain completely sedated during any surgical procedure. An anesthesiologist remains in the operating room during one's surgery, closely monitoring one's vitals and level of consciousness. Many operating rooms have a BIS monitor (Bispectral index) that provides a BIS value ranging from 0 to 100. This value reflects a patient's level of consciousness (A value of 0 represents EEG silence; close to 100 represents a fully awake adult; and the range between 40 and 60 equals the value recommended for a patient under general anesthesia). If one's heart rate became slightly elevated, the anesthesiologist would detect it and alert the surgeon. According to a study sponsored by the American Society of Anesthesiologists, for approximately fifteen years, the incidence rate of awareness during general anesthesia has been 0.1-0.4% (1-4 for 1000 patients). The statistics may be difficult to calculate due the fact that many patients who experience awareness do not share their stories or even remember the incident.

What can be done to prevent awareness?

All patients planning to have surgery should talk with their anesthesiologist ahead of time. During the conversation, both the anesthesiologist and patient should decide together on the safest form of anesthesia as well as discuss the patient's medical history at length. It is also important for the patient to answer the questions honestly about one's lifestyle and family history because even things such as alcohol may affect one's reaction.

For more information on anesthesia awareness, please visit:

http://www.asahq.org/patientEducation.htm

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