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General Anesthesia


General anesthesia is the use of medicine to put the entire body to sleep. It puts you into a state of unconsciousness. The brain cannot feel any pain.

Doctors trained in anesthesia carefully balance the amount of medicine that is needed.

Reasons for Procedure

General anesthesia is used for a surgery or a procedure that would be uncomfortable if you were awake. The medicine will help to:

  • Prevent pain
  • Relax the muscles
  • Stop certain reflexes
  • Prevent awareness of what is happening

Possible Complications

Many steps are taken to prevent problems. Possible risks include:

  • Allergic reaction to anesthetic used
  • Nerve damage or skin breakdown from positioning on the operating table
  • Sore throat or damage to throat, teeth, or vocal cords
  • Lung infections
  • Anesthesia awareness—where the patient becomes aware during the surgery, which is very rare
  • Stroke
  • Heart attack

Things that can increase the risk of problems are history of:

  • Smoking
  • Drinking alcohol
  • Chronic disease such as diabetes or obesity

What to Expect

Prior to Procedure

You will meet with a specialist before surgery. They will ask about overall health and any previous reaction to anesthesia. It is also important they know about any medicine that you are taking.

Food and drink may need to be avoided starting the night before the surgery.

Description of the Procedure

Some medicine may be given before anesthesia. It can help to prevent problems, such as nausea and vomiting. General anesthesia is broken down into 3 phases:

  • First phase—Medicine will be given that leads to loss of consciousness. These will be given through an IV or as gas through a mask. A breathing tube will be placed down your windpipe. A machine will help you breathe through surgery.
  • Middle phase—Medicine will be given based on your response. It will help to keep you asleep and keep breathing and heart rate where it should be.
  • Recovery phase—The anesthesia will be slowly reversed. New medicine will allow you to wake up. The breathing tube will be removed when you start to wake.
Endotracheal Intubation
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Immediately After Procedure

The care team will watch closely for any problems.

How Long Will It Take?

The time will depend on the type of surgery.

How Much Will It Hurt?

General anesthesia numbs all pain. The brain will not sense any pain signals.

Average Hospital Stay

The hospital stay will depend on the surgery. A poor reaction to anesthesia may require a longer stay as well.

Postprocedure Care

Anesthesia can have some effects for 24 hours or longer. Major decisions or dangerous activity should be avoided.

Call Your Doctor

It is important for you to monitor your recovery after you leave the hospital. Alert your doctor to any problems right away. Call your doctor if there are:

  • Signs of infection, including fever and chills
  • Persistent nausea or vomiting
  • Cough, shortness of breath, or chest pain
  • Lightheadedness or fainting

If you think you have an emergency, call for emergency medical services right away.


American Association of Nurse Anesthetists

American Society of Anesthesiologists

Canadian Resources

Canadian Anesthesiologists' Society

Health Canada


Anesthesia—what to expect. Kids Health—Nemours Foundation website. Available at: Updated September 2015. Accessed February 13, 2020.

General anesthesia. American Pregnancy Association website. Available at: Updated August 2015. Accessed February 13, 2020.

Pollard R, Coyle J, Gilbert R, Beck J. Intraoperative awareness in a regional medical system: A review of 3 years' data. Anesthesiology. 2007;106(2)269-274.

Sackel DJ. Anesthesia awareness: an analysis of its incidence, the risk factors involved, and prevention. J Clin Anesth. 2006;18(7):483-485.