A guide to understanding the risks of anesthesia

Anesthesia has come a long way since the days when surgery patients were given a swig of whiskey and a bullet to bite. Here are some of the risks associated with anesthesia that you should know.

Yes. The drugs used to induce unconsciousness and relax muscles for surgery may cause side effects, though they are usually minor.

• A Canadian study of nearly 113,000 surgery patients found that about one in 10 experienced after-effects from anesthesia.
• The most common problems were nausea, vomiting and sore throat.
• Only a tiny portion of those complaints — less than half of one percent — were serious.
• Yes, surgery patients do die from anesthesia, but that probably occurs in fewer than one in 10,000 operations.

Yes. One or two patients regain consciousness during surgery per 1,000 surgeries.

• It has become fodder for Hollywood filmmakers and daytime talk show hosts: a patient wakes up during surgery but is unable to speak or let anyone know that the anesthesia has failed.
• About half the time, these patients later report that they could hear sounds during the surgery, such as doctors and nurses talking.
• One of four "anesthesia awareness" patients feel the pain of scalpels cutting their flesh or tubes being inserted down their throats, according to a study by Emory University anesthesiologists.
• It's important to note that anesthesia awareness is rare. It is estimated that about 26,000 patients in the United States experience the phenomenon, but more than 20 million people undergo general anesthesia.
• The problem usually arises when a patient receives too little anesthesia, due to an error by the anesthesiologist or equipment failure. Patients are more likely to become aware during certain procedures, including cardiac surgery, that may require lower doses of anesthesia, or while being treated for trauma, since it's harder to deliver the right dose of anesthetic during emergency surgery.
• While only a minority of patients who experience anesthesia awareness feel physical pain, the memory of being awake during surgery can leave emotional scars. Two years later, about half of patients have symptoms of post-traumatic stress disorder, which can include flashbacks and recurring nightmares.

You can reduce the chance that you'll wake up during surgery by being completely honest about what drugs (prescription, non-prescription or recreational) and dietary supplements you take and whether you drink or smoke.

• This is no time to cover up a bad habit, since certain drugs can influence how well anesthesia works, and poor lung function can affect the dose of medication needed to induce unconsciousness.
• Studies show that even heavy exposure to second-hand smoke can reduce the effectiveness of anesthesia.
• If you smoke and need an operation, doctors suggest quitting two months beforehand. If you can't, don't smoke for 24 hours prior to surgery.

Although anesthesia has come a long way it is not completely perfected. The drugs used today to induce the deep sleep of general anesthesia also alter your breathing, blood pressure and other body functions, so it's no surprise that they can cause side effects. What's more, anesthesiologists may provide the wrong dose or fail to take necessary actions when a patient has a bad reaction. Keep this guide in mind and understand the risks involved with anesthesia.