"Doc, make sure I don't wake up in the middle of the operation today." This sentiment is one that's frequently expressed by my patients, and by patients in every surgical setting. Unanticipated awareness under anesthesia - intraoperative awareness - is rare, yet it still happens. We must recognize that this is a preventable problem and work together to reduce the chance of any occurrence in our facilities. Here's a quiz to test your awareness of awareness.

1. What is intraoperative awareness?

A. Waking up during the procedure
B. Recalling the sounds and conversations
C. Feeling and remembering pain
D. Dreaming during a procedure
E. All of the above

Correct answers: A, B and C. "Intraoperative awareness occurs when a patient becomes conscious during a procedure performed under general anesthesia and subsequently has recall of these events," says the American Society of Anesthesiologists' "Practice Advisory for Intraoperative Awareness." What patients experience and remember may include snippets of conversation, pain and the sensation of not being able to breathe. Severe cases can cause psychological trauma resulting in post-traumatic stress disorder. The dramatic details of these events often make for sensational media reports. Children are more likely than adults to recall their dreams after general anesthesia, but dreaming during surgery doesn't have any known long-term consequences and isn't considered awareness.

2. How common is intraoperative awareness?

A. Quite common
B. Common
C. Uncommon
D. Never occurs

Correct answer: C. Although we hear much talk about intraoperative awareness in the media, it's a very rare occurrence. Studies that report an incidence of 1 to 2 cases per 1,000 patients may overstate the actual occurrence. A three-year study of more than 87,000 patients published in the journal Anesthesiology in February 2007 reported that awareness incidence was 1 per 14,450 patients in adults having both inpatient and outpatient surgery. However, with 21 million patients receiving general anesthesia each year in the United States, awareness occurs in patients between 1,400 and 40,000 times a year. Regardless of its frequency, patients are extremely concerned about it.

3. Who is at greater risk for awareness?

A. Trauma patients
B. Obese patients
C. Females
D. Cardiac patients

Correct answers: A and D. Incidence of awareness is greater in patients who require smaller doses of anesthesia, such as trauma patients with depressed vital signs, cardiac patients and others requiring less anesthesia to avoid side effects. Patients who have unstable vital signs may not tolerate large doses of anesthetics and thus may be at risk for awareness. Patients taking betablockers and calcium channel blockers may have a higher risk of awareness, as these drugs may mask some of the vital sign changes associated with light anesthesia, such as increased heart rate or blood pressure. Although it's difficult to rely on children's testimony, recent studies report that pediatric patients may be more at risk for awareness than adults.

4. Does age affect risk of awareness?

A. Yes
B. No.

Correct answer: A. Many earlier studies of pediatric patients reported extremely high rates of "awareness," up to 8 percent. An Australian study reported in 2005 an incidence of 0.8 percent in a pediatric population between the ages of 5 and 12. This may be related to altered anesthetic pharmacology in children. Anesthesia providers may also hesitate to give large doses of anesthetics to children because pediatric vital signs can change rapidly. The CARE (Childhood Awareness and Recall Evaluation) study, sponsored by Aspect Medical, will evaluate the incidence of pediatric intraoperative awareness in a multicenter fashion and is currently enrolling patients in three academic medical centers. Luckily, children are less likely to have negative associations attached to their recollections.

5. Using a consciousness monitor is the only means of detecting awareness.

A. True
B. False

Correct answer: B. Monitoring consciousness runs the gamut from looking for physical signs to measuring the EEG waveform with sensors connected to a consciousness monitor. Clinical signs include body movement, eye opening, eyelash reflex, pupil responses, perspiration and tearing. Vital signs such as heart rate or blood pressure can increase if the patient is experiencing stress in the operating room. Anesthetic monitors often include a measure of end-tidal anesthetic concentrations as well as end-tidal carbon dioxide. Several forms of consciousness monitors are currently marketed, but fewer than 20 percent of the ORs in the United States have such a monitor.

Before the advent of these monitors (also known as brain monitors or awareness monitors), anesthesia providers were trained to believe that changes in heart rate and blood pressure were good clues to the changes in depth of anesthesia. But since we knew these clues were not the whole story, we were obliged to routinely overmedicate for fear of undermedicating - hence, the "art of the controlled overdose," as some like to say. Changes in heart rate and blood pressure have been shown to be highly unreliable signs of the depth of anesthesia.

6. Only the anesthesia provider should be concerned with the depth of consciousness of the patient.

A. True B. False

Correct answer: B. Everyone in the OR has a role in monitoring the consciousness of a patient. Surgeons, nurses and techs should feel free to mention any change in the patient's condition. The anesthesiologist should acknowledge the observation and respond in a professional manner. Most of the time, these changes are reflex responses to surgical stimuli and don't mean that the patient is returning to consciousness.

7. Which are the signs of a return to consciousness?

A. Increased heart rate
B. Decreased blood pressure
C. Increased respiratory rate
D. Movement of fingers

Correct answers: A, C and D. As the anesthesiologist reduces the amount of medication at the end of surgery, the patient's vital signs should return to their pre-operative values. The patient will begin to move and breathe again after muscle relaxants are reversed or metabolized. There may be coughing in response to airway irritation, such as an endotracheal tube, laryngeal mask or secretions. Proper titration of anesthetics helps the patient recover quickly, within five to 20 minutes after the end of surgery, depending on the depth of sedation. Elderly patients or patients with multiple co-morbid conditions might take longer to emerge. Children usually emerge more quickly than adults.

8. Which type of consciousness monitor uses a stimulus to assess depth of awareness?

A. Bispectral index
B. Cerebral state index
C. Auditory evoked potential
D. M-entropy

Correct answer: C. Auditory evoked potential monitors use a sound stimulus to evoke a defined auditory pathway response. The Bispectral index (the most common monitor type), cerebral state index and M-entropy use processed EEG signals.

9. On the BIS index, which range of values is the target for reducing the chance of awareness and minimizing over-sedation?

A. 75 to 85
B. 55 to 65
C. 35 to 45
D. 25 to 30

Correct answer: B. With a BIS level of about 60, the patient should be anesthetized appropriately. Preventing oversedation is just as important as preventing undersedation. BIS scores below 45 were associated with increased one-year mortality in a 2005 study by Terri Monk, MD. While some studies suggest that post-op cognitive dysfunction may be associated with reduced BIS scores, a 2006 study by Ehab Farag, MD, suggested that lower BIS scores were correlated with slightly improved mental status testing at four to six weeks' post-op time.

10. How much are patients willing to pay to avoid awareness?

A. $1,000
B. $206
C. $34
D. Nothing

Correct answer: C. Sixty patients surveyed by Duke University researchers said they'd pay an extra $34 to have a consciousness monitor used during their procedure.