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General Anesthesia is a technique during which the patient is rendered unconscious. General Anesthesia provides analgesia (you have no pain), amnesia (you are unaware and have no memory), and relaxation (your muscles are relaxed). General Anesthesia is usually started and maintained by giving the patient an intravenous drug (into a vein), an inhalation drug (a gas which you breathe), or a combination of both. The anesthesiologist will monitor the progress of the surgery, the depth of your anesthesia and your cardiovascular and respiratory status. The depth of anesthesia can be changed by increasing or decreasing the amount of drug given. As the surgeon gives up the procedure, the anesthesiologist reduces the depth of anesthesia so the patient will awaken at the end of the procedure or shortly thereafter and will regain consciousness.

What can I expect before ?

Nowadays, most patients come to the hospital on the day of their operation, and are seen by the anesthesiologist in the pre-anesthetic assessment clinic or the day of their scheduled surgical procedure. Before meeting the anesthesiologist you could be requested to answer to a questionnaire. This questionnaire will help you organize and provide important information for your anesthesiologist. You can choose your anesthesiologist, though the multiple duties and assignments shared by the anesthetic staff may make it logistically difficult to have a given member of the staff available on the day of your operation. Please check with your surgeon about your local situation. He or she will review your medical history, examine you, and order any necessary laboratory tests, electrocardiogram (EKG) and chest X-ray. He or she will make sure that any medical conditions, which might complicate your anesthetic, are being treated as well as possible. The history should include past and current medical problems, current and recent drug therapy, unusual reactions or responses to drugs, and any problems or complications associated with previous anesthetics. A family history of adverse reactions associated with anesthesia should also be obtained. lnformation about the anesthetic that the patient considers relevant should also be documented. Occasionally, the anesthesiologist will request an opinion from another specialist, such as a cardiologist, to help in your assessment. The different types of anesthesia appropriate for you and the relative risks according to the American Society of Anesthesiologists Physical Status Classification and New York Heart Association Classification will be explained. Very rarely, your operation may be postponed or cancelled because of the risks involved. The anesthesiologist who is assigned to look after you on the day of your operation will review this information, and make the final decision with you about the details of your anesthetic. Your anesthesiologist will inform you about NPO (nothing per os): on the morning of surgery, you should have nothing to eat or drink. You may brush your teeth or rinse your mouth, but you should not eat or drink anything. If, however, you routinely take medications for your blood pressure or heart in the morning, you should take your usual medications with a sip of water.

What can I expect during ?

General Anesthesia is a technique during which the patient is rendered unconscious. General Anesthesia provides

  1. analgesia (you have no pain),
  2. amnesia (you are unaware and have no memory),
  3. muscle relaxation (your muscles are relaxed).

When you arrive in the operating room, you will be prepared for surgery. An intravenous cannula will be introduced in a vein of your hand or forearm to infuse anesthetic medications and fluids during surgery. ( CLICK HERE. You can watch a video clip of vein cannultion in the operating room). In the operating room, monitors for your breathing, heart, and blood pressure will be placed on you. Your anesthesiologist usually will control continuously during surgery the following parameters:



These parameters are mandatory in any type of anesthesia. In certain type of surgery (neurosurgery, cardiac surgery, transplantation surgery ecc.) may be necessary to monitor other functional parameters. Your anesthesiologist will inform you about this.

You will be asked to breathe through an oxygen mask for a few breaths as the anesthetic is given through your intravenous line (IV). The next thing you should remember is awakening in the recovery room. You may be a little confused when you wake up in the recovery room, but that should improve as the anesthetic clears.

Operating Room

Surgery and General Anesthesia. Click on the figure to magnify

For general anesthesia endotracheal intubation is required to provide a patent airway particularly when the patient is at risk for aspiration an for prolonged controlled ventilation. Intubation is usually performed with an instrument called laryngoscope and with an appropriate tube (endotracheal tube), which is placed just bellow the vocal cords ( CLICK HERE: you can watch a short video clip about the intubation in an operating room. This video clip is taken from http://www.streamor.com/index.html)

Endotrachela Tube and laryngoscopeEndotracheal intubation

Endotracheal intubation (figure on the right) performed with a tube and a laryngoscope (figure on the left). Click on the figures to magnify


Nowadays there are airway management devices that can be used as an alternate to endotracheal intubation. One of the advantages of these devices is to reduce the incidence of sore throat. The Laryngeal Mask Airway (LMA) is one of these.

Laryngeal mask airwayLaryngeal mask airway

Laryngeal Mask Airway (LMA): an alternate to endotracheal intubation. Click on the figures to magnify

LMA introductionLMA position

Insertion of Laryngeal Mask Airway and relationship with trachea (red anterior pipe anterior in the figure on the right). Insertion of this device dose not require the use of laryngoscope. Click on the figures to magnify


Ensuring lack of awareness and amnesia are implicit goals of a general anesthetic. Your anesthesiologist will take care to avoid intraoperative awareness, regulating and assessing anesthesia depth from induction through emergence. This goal will be obtained assuring adequate administration of anesthetic substance through a sophisticated apparatus called anesthesia machine. The function of the anesthesia machine is to prepare a gas mixture of precisely known but variable composition. The machine provides a controlled flow of oxygen, air and anesthetic vapors. A mechanical ventilator is connected to the breathing system freeing up the anesthesiologist's hands for other tasks. As the surgeon finishes the procedure, the anesthesiologist reduces the depth of anesthesia so the patient will awaken at the end of the procedure or shortly thereafter. At the end of anesthesia you may be a little confused when you wake up in the recovery room, but that should improve as the anesthetic clears. If you have any pain, you will be given pain medications through your IV. When you have recovered sufficiently from your anesthetic, your pain is under control, and your vital signs are stable, you will be transferred to your room or prepared to go home.

What can I expect after ?

After general anesthesia the most common complication is nausea and vomiting. This occurs more frequently in children, those who have experienced nausea with previous anesthetics, and those who are susceptible to motion sickness. Those with diabetes, obesity and pregnancy are also more prone to get sick. This problem can be prevented or treated if it occurs. Minor complications such as sore throat, headache, hoarseness, drowsiness, muscle aches and fatigue are common for the first several days following surgery. Most patients have no problem whatsoever, but if you have had any of the above problems, please tell your anesthesiologist, so he or she can try to prevent a recurrence of the problem. A the end of the operation you can feel pain in the operated area. Anesthesiologists have developed its treatment to the point where it is possible to avoid severe pain in most circumstances, particularly after surgery. Your anesthesiologist will provide medications to control the postopeartive pain.

What are the risks ?

Are there risks with anesthesia? The answer is YES.

The likelihood of any complication with general anesthesia occurring depends on your pre-operative medical condition, the nature of your operation and the anesthetic technique used. Adverse effects and serious complications are very rare, but the possibility does exist. There is no accurate measure of the overall risk of anesthesia. However the chance of a healthy person dying as a result of anesthesia is probably 1/151,000, 1/244,000 (4-5 cases every 1,000,000 surgical procedures). This is certainly comparable with the risks of commercial airline travel and much safer (25 time less) than travelling by car. Certainly, you have more risk to have an accident during your ordinary life (driving a car, crossing a road, travelling by plain etc.). You must know that only 40 to 50 years ago, several studies placed death from anesthesia at 1 in 1,560-13,000 surgical procedures. Of course, there are a number of infrequent, less serious complications, such as pain and bruising at the site of injections, headaches, and dental damage. These are usually easily treatable, get better quickly, and are also quite rare. Nausea is relatively common and is treated with appropriate medication. Sore throat associated with breathing tube placement is also quite common, but usually only lasts a day or so. If you are concerned about complications or feel you may have had a complication from previous anesthetics, please discuss this with your anesthesiologist. If your family members have had problems with anesthesia in the past, please tell the anesthesiologist prior to your surgery. Such prior warning will allow the anesthesiologist to plan the appropriate treatment to prevent recurrent problems if possible. Remember: complications from anesthesia are rare. The more common problems are usually minor and treatable.

Tutorial from the National Medical Library

From the National Medical Library a tutorial about general anesthesia. The tutorial is for informational purposes only and its content is general information and not medical advice. Content is not intended to be a substitute for professional medical advice. Always seek the advice of your anesthesiologist with any questions you may have regarding a medical condition or medical treatment.

Go to the NML tutorial.......


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