General Anesthesia
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General Anesthesia


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General anesthesia is a type of anesthesia that works by putting the entire body to sleep. It is most often used during emergency or extensive surgery. Doctors trained in anesthesia (anesthesiologists) carefully balance the amount of anesthesia given by closely monitoring the body’s functions. Medications are used to prevent pain, relax the muscles, and regulate body functions. When the surgery is over, medications are given to reverse the process.

Parts of the Body Involved

With general anesthesia, the whole body is involved as it is put to sleep. Breathing, heart rate, and oxygen levels are all closely monitored. Other parts of the body that are typically involved include:

  • Arm or hand—An intravenous (IV) line is placed in the arm to deliver fluid and medications.
  • Finger—A pulse oximeter is placed on the fingertip to measure oxygen levels.
  • Trachea or windpipe—Once asleep, a tube is placed in the trachea to deliver oxygen and anesthetic gases into the lungs (intubation).

Endotracheal Intubation

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Reasons for Procedure

General anesthesia is used so that surgery can be performed without you being aware of it or feeling any pain.

Risk Factors for Complications During the Procedure

Risk factors are conditions that may increase your risk for complications during general anesthesia. These may include:

  • Medical conditions—heart, respiratory, kidney conditions, and diabetes
  • Certain medications—especially those that increase bleeding (eg, aspirin)
  • Smoking
  • Alcohol use—may alter the way the liver handles anesthesia
  • Time of last food intake—a full stomach may cause food to enter the lungs
  • Adverse reactions to anesthesia or family history of adverse reactions, such as malignant hyperthermia
    • Malignant hyperthermia is an inherited disease that affects a person when they undergo general anesthesia. It causes severe muscle contractions, a rapid rise in body temperature, and , if not immediately treated, eventual deterioration of muscle tissue, kidney failure, and finally death. Fever-reducing medicines, a cooling blanket, and fluids given intravenously or orally can be used to treat an episode. It is important to inform your doctor of family medical history so that the proper anesthetic medication can be used.
  • Food or drug allergies

What to Expect

Prior to Procedure

Unless you are having emergency surgery, you will meet with an anesthesiologist before surgery. You will be asked about your health history and medications. It is important to disclose all medications, even herbal remedies, since they may have an effect on your anesthesia experience. You need to tell the anesthesiologist if you have dentures. Your height and weight will be taken to gauge how much anesthetic to use.

You will also be asked if you or any family members have ever had anesthesia before, and how you (or they) reacted to it. You will be told to fast the night before surgery so that there is nothing in your stomach during surgery. Your anesthesiologist may instruct you to take certain medications in the morning before surgery.

Description of the Procedure

General anesthesia is broken down into three phases. The initial phase is referred to as induction . This phase consists of giving medications that result in the loss of consciousness. Induction anesthetics are given through an IV or through a gas into the lungs. In the middle or maintenance phase, medications are given based on your responses; these may keep you asleep or regulate your body functions. The recovery or emergence phase is the last phase, and is timed to slowly reverse the anesthesia, and allow you to wake up.

After Procedure

As you wake up, you will be closely monitored in a recovery room (also called a postanesthesia care unit) by your anesthesiologist and specially trained nurses. If a breathing tube is used, it is removed once you can breathe by yourself. You will be given pain medication if you are experiencing any pain.

How Long Will It Take?

General anesthesia takes as long as necessary. The type of surgery will dictate how long the anesthesia takes, as it begins before surgery and ends once the surgery is complete.

Will It Hurt?

General anesthesia numbs all pain sensations. Since you are asleep, your brain doesn’t sense any pain signals. A combination of medicines is used to block pain, awareness, and memory during the procedure.

Possible Complications

Every precaution is used to prevent complications from general anesthesia. Often, medications are given in advance to prevent certain complications, such as nausea and vomiting. Even so, complications may occur and include:

  • Nausea and vomiting
  • 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
  • While rare, there is a small risk of the following complications, especially among the elderly or those with medical problems:
  • Anesthesia awareness (when the patient "wakes up" during surgery) is a rare complication that may occur in 0.1% to 0.2% of cases (recent data suggests even lower incidence of 0.0068%).

Average Hospital Stay

The length of time in the hospital depends upon the type of surgery performed, as well as your reaction to surgery and anesthesia. You may be sent home the same day, or need to spend some time in the hospital.

Postoperative Care

Once you have recovered from anesthesia, you will be sent to a hospital room or home, again depending upon the type of surgery. Your surgeon will provide any necessary instructions specific to your surgery.


General anesthesia is a safe procedure, due in large part to new medications and better monitoring devices. Since it may cause you to feel drowsy or tired, it is important that you don’t drive or perform other tasks that require you to be alert for at least 24 hours or longer if necessary.

Call Your Doctor If Any of the Following Occurs

Once you leave the hospital, it is essential that you monitor your recovery. Call your doctor at once if you experience any of the following:

  • Cough
  • Shortness of breath
  • Chest pain
  • Severe nausea or vomiting


American Association of Nurse Anesthetists

American Society of Anesthesiologists


Canada Health Portal

The Canadian Anesthesiologists' Society


Anesthesia and you. American Society of Anesthesiologists website. Available at: . Accessed September 2, 2005.

Anesthesia: options and considerations. Mayo Clinic website. Available at: . Accessed September 2, 2005.

Anesthetics, general (systematic). US National Library of Medicine and the National Institutes of Health website. Available at: . Accessed September 2, 2005.

General anesthesia. US National Library of Medicine and the National Institutes of Health website. Available at: . Accessed September 6, 2005.

The Joint Commission website. Available at:

Pollard R, Coyle J, Gilbert R, Beck J: Intraoperative awareness in a regional medical system: A review of 3 years' data. Anesthesiology 106 . 269-274.2007

Sackel DJ. Anesthesia awareness: an analysis of its incidence, the risk factors involved, and prevention. Journal of Clinical Anesthesia. 18(7):483-5, 2006 Nov.

Last reviewed December 2007 by John C. Keel, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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