General anesthesia is overall very safe; most people, even those with significant health conditions, are able to undergo general anesthesia itself without serious problems.
In fact, your risk of complications is more closely related to the type of procedure you're undergoing and your general physical health, rather than to the type of anesthesia.
Older adults, or those with serious medical problems, particularly those undergoing more extensive procedures, may be at increased risk of postoperative confusion, pneumonia, or even stroke and heart attack. Specific conditions that can increase your risk of complications during surgery include:
- Obstructive sleep apnea
- High blood pressure
- Other medical conditions involving your heart, lungs or kidneys
- Medications, such as aspirin, that can increase bleeding
- History of heavy alcohol use
- Drug allergies
- History of adverse reactions to anesthesia
These risks are generally related to the surgery itself, not the anesthesia.
Estimates vary, but about 1 or 2 people in every 10,000 may be partially awake during general anesthesia and experience what is called unintended intraoperative awareness. It is even rarer to experience pain, but this can occur as well.
Because of the muscle relaxants given before surgery, people are unable to move or speak to let doctors know that they are awake or experiencing pain. For some patients, this may cause long-term psychological problems, similar to post-traumatic stress disorder.
This phenomenon is so rare that it's difficult to make clear connections. Some factors that may be involved include:
- Emergency surgery
- Cesarean delivery
- Use of certain medications
- Heart or lung problems
- Daily alcohol use
- Lower anesthesia doses than are necessary used during procedure
- Errors by the anesthesiologist, such as not monitoring the patient or not measuring the amount of anesthesia in the patient's system throughout the procedure