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Last updated January 1, 2014

Intra-Operative Awareness (IOA)

More common than thought

Jenny Thompson, Health Sciences Institute, 10/27/2003

A patient identified as "J.L." was undergoing a coronary bypass operation at an Illinois hospital in 1998 when his anesthesia-induced sleep gradually lifted a full 45 minutes before the end of his surgery. Because of a neuromuscular blocking agent that had also been administered, J.L. was temporarily paralyzed and could not communicate with doctors or nurses to let them know he was completely awake and aware. And worse than that, he could feel the pain.

I had heard about the phenomenon of intra-operative awareness (IOA; also known as anesthesia awareness), but until I saw a report on the Today show last week, I didn't realize just how common it is.

Fortunately, this terrifying ordeal can often be avoided when patients are informed about anesthesia dangers and then make a point of communicating their concerns to doctors and anesthesiologists.

How many is way too many?
As many as 40,000 patients may experience intra-operative awareness every year, according to the American Association of Nurse Anesthetists (AANA). But the AANA web site also acknowledges that there are no precise figures available to accurately estimate just how many surgery patients experience IOA.

A woman named Carol Weihrer believes the figure is much higher, perhaps higher than 200,000 patients each year. In her opinion, the community of anesthesiologists is reluctant to fully recognize and discuss IOA, and therefore underestimates its effects as well as its frequency. Ms. Weihrer experienced anesthesia awareness during a surgery several years ago. Since then she's made it her mission to educate both patients and practitioners about the risk of IOA.

According to her anesthesia awareness web site, many doctors are unfamiliar with the long-range problems associated with IOA. In the case of J.L., for instance, after his coronary bypass he experienced post-traumatic stress disorder (PTSD), emotional problems, and sexual dysfunction. Ms. Weihrer has also experienced PTSD, including nightmares and flashbacks. And she adds, "The memory never goes away."

C gets in the way
The American Association of Nurse Anesthetists identifies the three primary causes of IOA as the misuse or failure of anesthesia equipment, inadequate anesthesia, and patient-related factors. In this third category, variables such as advanced age, obesity, and drug or alcohol abuse may compromise the effect of anesthesia. In fact, even high doses of vitamin C may interfere.

In the e-Alert "C Saw" (5/28/03), HSI Panelist Allan Spreen, M.D., explained that a high level of vitamin C is so detoxifying that it can complicate the anesthesia process. He said, "Many times I've had patients tell me that their anesthesiologist was surprised at how much medication was required to knock them out." For those patients who take large doses of vitamin C (something that Dr. Spreen generally recommends), he suggests that they gradually taper off their daily dose until reaching nearly zero just before the surgery.

Talking points
As for the other variables (age, obesity, etc.), this is where communication between patient and doctor is crucial. After discussing any personal variables, tell your doctor that you'd like to meet the anesthesiologist before your surgery; preferably, well in advance of being wheeled into the operating room. Let both of them know that you're concerned about IOA. Once the subject has been opened, here are three important issues to ask about:

  • Some anesthesia procedures leave the patient paralyzed during the operation, making it impossible to communicate anesthesia awareness. Ask your anesthesiologist if this will be the case during your surgery. If so, ask if there's another suitable method available that will not paralyze you.
  • Ask if the anesthesia tanks and equipment have been recently checked.
  • Ask if any monitors will be used to determine if you're inadequately anesthetized. For instance, there are two types of brain monitors that specifically assess anesthesia response: Bispectral Index and Patient State Analyzer.

Finally, never take anesthesia for granted. It's not routine, it's a critical aspect of your surgery. And as the experiences of J.L. and Carol Weihrer have demonstrated, unsuccessful anesthesia can make recovery much longer and more painful than it has to be.




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