Topic Overview

What is anesthesia?

Anesthesia controls pain during surgery or other medical procedures. It includes using medicines, and sometimes close monitoring, to keep you comfortable. It can also help control breathing, blood pressure, blood flow, and heart rate and rhythm, when needed.

An anesthesiologist or a nurse anesthetist takes charge of your comfort and safety during surgery. This topic focuses on anesthesia care that you get from these specialists.

Anesthesia may be used to:

• Relax you.
• Block pain.
• Make you sleepy or forgetful.
• Make you unconscious for your surgery.

Other medicines also may be used to relax your muscles during surgery.

What are the types of anesthesia?

• Local anesthesia numbs a small part of the body. You get a shot of medicine (anesthetic) directly into the surgical area to block pain. Sometimes the doctor will apply a numbing medicine to part of your body, such as your nose or mouth. Local anesthesia is used only for minor procedures. You may stay awake during the procedure, or you may get medicine to help you relax or sleep.
• Regional anesthesia blocks pain to a larger part of your body. Anesthetic is injected around major nerves or the spinal cord. You may get medicine to help you relax or sleep. Major types of regional anesthesia include:
  • Peripheral nerve blocks. A nerve block is a shot of anesthetic near a specific nerve or group of nerves. It blocks pain in the part of the body supplied by the nerve. Nerve blocks are most often used for procedures on the hands, arms, feet, legs, or face.
  • Epidural and spinal anesthesia. This is a shot of anesthetic near the spinal cord and the nerves that connect to it. It blocks pain from an entire region of the body, such as the belly, hips, or legs.
• General anesthesia affects the brain as well as the entire body. You may get it through a vein (intravenously, or IV), or you may breathe it in. With general anesthesia, you are completely unaware and do not feel pain during the surgery. General anesthesia often causes you to forget the surgery and the time right after it.

What determines the type of anesthesia used?

The type of anesthesia used depends on several things:

• Your past and current health. The doctor or nurse will consider other surgeries you have had and the health problems you have, such as heart disease, lung disease, or diabetes. You also will be asked whether you or any family members have had an allergic reaction to any anesthetics or other medicines.
• The reason for your surgery and the type of surgery.
• The results of tests, such as blood tests or an electrocardiogram (EKG, ECG).

Your doctor or nurse may prefer one type of anesthesia over another for your surgery. In some cases, your doctor or nurse may let you choose which type to have. Sometimes, such as in an emergency, you do not get to choose.

What are the potential risks and complications of anesthesia?

Major side effects and other problems of anesthesia are not common, especially in people who are in good health overall. But all anesthesia has some risk. Your specific risks depend on the type of anesthesia you get, your health, and how you respond to the medicines used.

Some health problems increase your chances of problems from anesthesia. Your doctor or nurse will tell you which of your health problems could affect your care.

Your doctor or nurse will closely watch your vital signs, such as your blood pressure and heart rate, during anesthesia and surgery so that you can avoid most side effects and problems.

How should you prepare for anesthesia?

Make sure you get a list of instructions to help you prepare for your surgery. Your surgeon will also let you know what will happen when you get to the clinic or hospital, during surgery, and afterward.

Your doctor will tell you when to stop eating and drinking before your surgery. When you stop depends on your health problem and the type of anesthesia that will be used. If you take any medicines regularly, ask your doctor or nurse if you should take your medicines on the day before or the day of your surgery.

You have to give your consent to be given anesthesia. Your doctor or nurse will discuss the best type of anesthesia for you and review risks, benefits, and other choices.

Many people are nervous before they have anesthesia and surgery. Mental relaxation methods as well as medicines can help you relax.

What happens when you are recovering from anesthesia?

Right after surgery you will be taken to the recovery room. Nurses will care for you there under the direction of an anesthesiologist. A nurse will check your vital signs and any bandages and ask about how much pain you have. If you are in pain, don't be afraid to say so.

Some effects of anesthesia may last for many hours after surgery. If you had local or regional anesthesia, you may have some numbness or reduced feeling in part of your body. Your muscle control and coordination may also be affected.

Other common side effects of anesthesia are closely watched and managed to reduce your discomfort. These side effects include:

• Nausea and vomiting. In most cases, this can be treated and does not last long.
• A mild drop in body temperature. You may feel cold and may shiver when you first wake up.

For minor surgeries, you may go home the same day. For more complicated surgeries, you may have to move to a hospital room to continue your recovery. If you stay in the hospital, your doctor or nurse will visit you to check on your recovery from anesthesia and answer any questions you have.

Frequently Asked Questions

Preparing for Anesthesia

Being well-prepared for anesthesia may help you remain calm and relaxed. If you take the time to learn about your procedure and the anesthesia, you will be better able to understand the information and instructions you are given. Knowing what to expect can help decrease tension and anxiety.

Usually, your surgeon's office, clinic, or hospital will contact you in advance to give you information about what to do the evening before and the day of the procedure. Your surgeon will also provide information about what will happen when you arrive at the clinic or hospital, during the procedure, and afterward.

Food and drink restrictions

As part of getting ready for your procedure, you are not allowed to eat or drink anything for a certain time period before anesthesia. The following times are averages. In some cases, such as in those people with gastroesophageal reflux disease (GERD), the restrictions must be started earlier for safety.

• Do not eat for 6 hours before anesthesia.
• You may drink clear liquids only (water, filtered apple juice, black coffee or tea, and clear carbonated beverages such as Seven-Up) up to 2 hours before your surgery. You should having nothing else to eat or drink for at least 6 hours before anesthesia.

Food and fluids are restricted to reduce the risk of aspiration by reducing the contents of your stomach. Aspiration occurs when an object or liquid is inhaled into the respiratory tract when a person regurgitates contents into the throat. Aspiration during anesthesia is very uncommon, but it can cause severe complications.

Medicine restrictions

If you take any medicines on a regular basis, such as diabetes medicines or heart medicines, ask your surgeon whether you should take your medicines on the day before or the day of your procedure. Some medicines may interact with the anesthetics and other medicines used for anesthesia.

Informed consent

Before any nonemergency surgery or procedure, most surgery centers and hospitals have a surgery consent for you to sign. This is called an informed consent, because your surgeon will explain why your surgery is needed, what it will involve, its risks and expected outcome, and how long it will take you to recover. After discussing this information, you may be asked to sign the informed consent. It needs to be signed before you receive any medicines that could affect your state of mind.

Your anesthesia specialist will discuss the anesthesia care for your surgery so that you will understand what is involved. You can then give your informed consent. You will be able to ask questions and express any concerns.

If the person to have anesthesia is a child or is mentally incompetent to sign a consent form, the consent may be signed by a responsible family member or guardian.

Mental relaxation techniques

Many people experience anxiety before medical procedures, especially surgery. Mental relaxation techniques can help reduce anxiety. If you will be awake during the procedure, you also can use these techniques to relax while it is being done. They can also be used to help reduce pain and anxiety after your procedure.

Some mental relaxation techniques that may be useful include:

• Optimistic self-recitation, in which you focus on and recite thoughts that are optimistic and positive.
• Guided imagery (visualization), a method of using your imagination to help you relax and release tension by concentrating on a pleasant experience or restful scene.
• Meditation, to help focus your attention on feeling calm and relaxed. You may want to focus on a single image, a sound, or your own breathing.
• Distraction techniques, such as listening to music through headphones.

Medicine given before anesthesia

You may be given a medicine before anesthesia. Medicines may be given by mouth or by injection immediately before anesthesia. Or sometimes the doctor will apply medicine to part of your body, such as your nose or mouth.

Medicine is given before anesthesia for many reasons, including:

• Relieve anxiety. The medicines most commonly given to relieve anxiety are benzodiazepines such as diazepam, lorazepam, and midazolam.
• Relieve or prevent pain. Medicines to relieve pain (analgesics) may be given to people who are in pain before the procedure begins as well as to reduce pain during the procedure.
• Reduce secretions. Certain medicines (anticholinergic agents) may be used to reduce secretions in the mouth and respiratory tract.
• Reduce the volume and acidity of fluids in the stomach to help reduce the risk of aspiration. Aspiration occurs when an object or liquid is inhaled into the respiratory tract. In some cases, medicines are given to reduce or neutralize stomach acidity in order to lower the risk of injury if stomach juices are regurgitated into the throat or inhaled into the airway.
• Reduce nausea and vomiting. People who are at risk for nausea and vomiting either during the procedure or during recovery may receive medicines called antiemetics.
• Control body functions. Medicines may be given that help control the body's automatic responses to the pain and stress of surgery. Other medicines may be given to help maintain heartbeat or blood pressure at a stable and regular level.

Other preparation

For many procedures, medicines are given through a vein (intravenously, IV). An IV is usually inserted into a vein in the hand or lower arm. When the IV is in place, medicines or fluids can be given quickly into your bloodstream. Children and some adults may find insertion of the IV painful and stressful. In these cases, the IV may be inserted after they have been sedated or after an inhaled anesthetic has been given through a mask.

Some of the instruments used to watch your breathing, blood pressure, and heart function may be placed on your body while you are being prepared for your surgery.

Helping children prepare for anesthesia

Children do better when receiving anesthesia if they know what to expect. You can help relieve your child's anxiety or fears by being calm and explaining what will happen at the clinic or hospital. Explain to your child that he or she will be in unfamiliar surroundings but that many doctors and nurses will be there to help.

It is best to be honest and explain that there may be some discomfort or pain after the procedure. But reassure your child that you will be close by. Bringing familiar items such as books or toys may help comfort and distract your child.

Types of Anesthesia

Anesthesia involves the use of medicines to block pain sensations (analgesia) during surgery and other medical procedures. Anesthesia also reduces many of your body's normal stress reactions to surgery.

The type of anesthesia used for your surgery depends on:

• Your medical history, including other surgeries you have had and any conditions you have (such as diabetes). You will also be asked whether you have had any allergic reactions to any anesthetics or medicines or whether any family members have had reactions to anesthetics.
• The results of your physical exam. A physical exam will be done to evaluate your current health and identify any potential risks or complications that may affect your anesthesia care.
• Tests such as blood tests or an electrocardiogram (EKG, ECG), if needed.
• The type of surgery that you are having.
  • You need to be able to lie still and remain calm during surgery done with local or regional anesthesia.
  • Young children usually cannot stay still during surgery and need general anesthesia.
  • Adults who are extremely anxious, in pain, or have muscle disorders also may have difficulty remaining relaxed and cooperative.
  • Some surgical procedures require specific positions that may be uncomfortable for long periods if you are awake.
  • Some procedures require the use of medicines that cause muscle relaxation and affect your ability to breathe on your own. In such cases, your breathing can best be supported if general anesthesia is used.

Based on your medical condition, your anesthesia specialist may prefer one type of anesthesia over another for your surgery. When the risks and benefits of different anesthesia options are equal, your anesthesia specialist may let you choose the type of anesthesia.

Anesthesia methods

There are several ways that anesthesia can be given.

• Local anesthesia involves injection of a local anesthetic (numbing agent) directly into the surgical area to block pain sensations. It is used only for minor procedures on a limited part of the body. You may remain awake, though you will likely receive medicine to help you relax or sleep during the surgery.
• Regional anesthesia involves injection of a local anesthetic (numbing agent) around major nerves or the spinal cord to block pain from a larger but still limited part of the body. You will likely receive medicine to help you relax or sleep during surgery. Major types of regional anesthesia include:
  • Peripheral nerve blocks. A local anesthetic is injected near a specific nerve or group of nerves to block pain from the area of the body supplied by the nerve. Nerve blocks are most commonly used for procedures on the hands, arms, feet, legs, or face.
  • Epidural and spinal anesthesia. A local anesthetic is injected near the spinal cord and nerves that connect to the spinal cord to block pain from an entire region of the body, such as the belly, hips, or legs.
• General anesthesia is given into a vein (intravenously) or is inhaled. It affects the brain as well as the entire body. You are completely unaware and do not feel pain during the surgery. Also, general anesthesia often causes forgetfulness (amnesia) right after surgery (postoperative period).

For some minor procedures, a qualified health professional who is not an anesthesia specialist may give some limited types of anesthesia, such as procedural sedation. Procedural sedation combines the use of local anesthesia with small doses of sedative or analgesic agents (painkillers) to relax you.

Medicines used for anesthesia

A wide variety of medicines are used to provide anesthesia. Their effects can be complex. And they can interact with other medicines to cause different effects than when they are used alone. Anyone receiving anesthesia—even procedural sedation—must be monitored continuously to protect and maintain vital body functions. The complex task of managing the delivery of anesthesia medicines as well as monitoring your vital functions is done by anesthesia specialists.

Medicines used for anesthesia help you relax, help relieve pain, induce sleepiness or forgetfulness, or make you unconscious. Anesthesia medicines include:

• Local anesthetics, such as bupivacaine or lidocaine, that are injected directly into the body area involved in the surgery.
• Intravenous (IV) anesthetics, such as fentanyl, propofol, or sodium thiopental, that are given through a vein.
• Inhalation anesthetics, such as isoflurane and nitrous oxide, that you breathe through a mask.

Other medicines that are often used during anesthesia include:

• Muscle relaxants, which block transmission of nerve impulses to the muscles. They are used during anesthesia to temporarily relax muscle tone as needed.
• Reversal agents, which are given to counteract or reverse the effects of other medicines such as muscle relaxants or sedatives given during anesthesia. Reversal agents may be used to reduce the time it takes to recover from anesthesia.

What Happens During Anesthesia

You likely will be given anesthesia by an anesthesia specialist. Final preparations before your surgery may include:

• Attaching instruments to check your breathing, oxygen level, heart rate, blood pressure, and other body functions.
• Positioning your body for surgery. You will be placed in a position that allows your surgeon access to the appropriate body area and avoids unnecessary pressure on any parts of your body.

The three main phases of anesthesia are induction, maintenance, and emergence.

Induction

The first phase of anesthesia, when you first begin receiving an anesthetic, is called induction.

For local anesthesia and many types of regional anesthesia, induction occurs when a local anesthetic is injected into the part of your body that needs to be anesthetized. Local and regional anesthesia often are given with other medicines that make you relaxed or sleepy (sedatives) or relieve pain (analgesics). These medicines are often given through a vein (intravenously, IV) before the local anesthetic is given.

Induction of epidural and spinal anesthesia may require the insertion of a needle into the space around the spinal nerves in the lower back. You will receive an injection of local anesthetic to reduce discomfort before the needle is inserted.

General anesthesia is often induced with IV anesthetics, but inhalation anesthetics also may be used.

• Because they enter directly into the bloodstream, intravenous anesthetics usually cause unconsciousness in less than 1 minute.
• Inhalation anesthetics also act quickly, but you must inhale them for a short time before they cause unconsciousness. Inhalation anesthetics are usually given through a mask that covers your nose and mouth. Induction with inhalation agents is mainly used for small children and adults who do not yet have an IV catheter.

Maintenance and monitoring

The second phase of anesthesia is called maintenance. During maintenance, the anesthesia specialist keeps a balance of medicines while carefully watching your breathing, heart rate, blood pressure, and other vital functions. Anesthesia is adjusted based on your responses during the procedure.

With local anesthesia and regional nerve blocks, maintenance frequently requires additional injections of sedatives to prolong the effects for more lengthy procedures.

For general anesthesia, after you are unconscious, anesthesia may be maintained with an inhalation anesthetic alone, with intravenous anesthetics, or most commonly with a combination of the two. Very often, inhalation anesthetics are given through an endotracheal (ET) tube or a laryngeal mask airway (LMA), which is an airway placed at the back of your throat but not in your windpipe like an ET tube. The airway is inserted after you become unconscious.

It also is common during general anesthesia for you to be given other medicines intravenously to maintain stable vital functions and to help prevent or decrease pain or nausea after the procedure.

Emergence

The final phase of anesthesia is called emergence. When your procedure is completed, the anesthesia specialist will stop giving the anesthetic. As your body clears the anesthetic medicines from your system, the effects begin to wear off, and your body functions begin to return. How quickly you emerge from anesthesia depends on the anesthetics and other medicines used and on your response to the medicines.

With local and regional anesthesia, emergence occurs as the effect of the injected anesthetic wears off and sensation returns. How long it takes for sensation to return depends on the type of anesthetic used, how much you were given, and the area of your body that was affected. Local anesthesia and some regional nerve blocks may wear off within 1 to 2 hours. Emergence from epidural or spinal blocks may take longer.

Emergence from general anesthesia begins when the intravenous or inhalation anesthetic is stopped. It may take a short time before your body clears the anesthetic from your system. You will be closely watched during emergence to make sure that you are breathing well on your own; your heartbeat, blood pressure, and other vital functions stay at normal levels; and your muscle control has returned. If an endotracheal tube or laryngeal mask airway was used, it will be removed as soon as you are breathing on your own.

In some cases, to help speed emergence, reversal agents are used to counteract, or reverse, the effects of certain anesthetics. These agents may help reduce the time it takes for you to recover from anesthesia.

Emergence does not mean you will have completely recovered from all the effects of anesthesia. Some effects may persist for many hours after anesthesia has ended. For example, you may have some numbness or reduced sensation in the part of your body that was anesthetized until the anesthetic wears off completely. Even if you feel alert and normal, your judgment and reflexes may still be affected for some time after your procedure, especially if you continue to take medicines, such as those to control pain or nausea. If you have numbness or reduced sensation longer than expected, contact your anesthesia specialist or doctor.

Risks and Complications

Although all types of anesthesia involve some risk, major side effects and complications from anesthesia are uncommon. Your specific risks depend on your health, the type of anesthesia used, and your response to anesthesia.

Personal risk factors

Your age may be a risk factor. In general, the risks associated with anesthesia and surgery increase in older people.

Certain medical conditions, such as heart, circulation, or nervous system problems, increase your risk of complications from anesthesia.

Some medicines can raise your risk of problems too. Make a list(What is a PDF document?) of all the prescription and over-the-counter medicines you take. And share your list with your doctors.

If you smoke, drink alcohol, or use illegal drugs, you may be more likely to have problems from anesthesia. It's important that you are honest when you talk with your surgeon and anesthesia specialist.

Complications from local anesthesia

When used properly, local anesthetics are safe and have few major side effects. But in high doses, local anesthetics can have toxic effects caused by being absorbed through the bloodstream into the rest of the body (systemic toxicity). This may significantly affect your breathing, heartbeat, blood pressure, and other body functions. Because of these potential toxic effects, equipment for emergency care must be immediately available when local anesthetics are used.

Complications from regional anesthesia

For regional anesthesia, an anesthetic is injected close to a nerve, a bundle of nerves, or the spinal cord. In rare cases, nerve damage can cause persistent numbness, weakness, or pain.

Regional anesthesia (regional nerve blocks, epidural and spinal anesthesia) also carries the risk of systemic toxicity if the anesthetic is absorbed through the bloodstream into the body. Other complications include heart or lung problems, and infection, swelling, or bruising (hematoma) at the injection site.

Spinal anesthesia medicine is injected into the fluid that surrounds the spinal cord (cerebrospinal fluid). The most common complication of spinal anesthesia is a headache caused by leaking of this fluid. It is more common in younger people. A spinal headache may be treated quickly with a blood patch to prevent further complications. A blood patch involves injecting a small amount of the person's own blood into the area where the leak is most likely occurring to seal the hole and to increase pressure in the spinal canal and relieve the pull on the membranes surrounding the canal.

Complications from general anesthesia

Serious side effects of general anesthesia are uncommon in people who are otherwise healthy. But because general anesthesia affects the whole body, it is more likely to cause side effects than local or regional anesthesia. Fortunately, most side effects of general anesthesia are minor and can be easily managed.

General anesthesia suppresses the normal throat reflexes that prevent aspiration, such as swallowing, coughing, or gagging. Aspiration occurs when an object or liquid is inhaled into the respiratory tract (the windpipe or the lungs). To help prevent aspiration, an endotracheal (ET) tube may be inserted during general anesthesia. When an ET tube is in place, the lungs are protected so stomach contents cannot enter the lungs. Aspiration during anesthesia and surgery is very uncommon. To reduce this risk, people are usually instructed not to eat or drink anything for a certain number of hours before anesthesia so that the stomach is empty. Anesthesia specialists use many safety measures to minimize the risk of aspiration.

Insertion or removal of airways may cause respiratory problems such as coughing; gagging; or muscle spasms in the voice box, or larynx (laryngospasm), or in the bronchial tubes in the lungs (bronchospasm). Insertion of airways also may cause an increase in blood pressure (hypertension) and heart rate (tachycardia). Other complications may include damage to teeth and lips, swelling in the larynx, sore throat, and hoarseness caused by injury or irritation of the larynx.

Other serious risks of general anesthesia include changes in blood pressure or heart rate or rhythm, heart attack, or stroke. Death or serious illness or injury due solely to anesthesia is rare and is usually also related to complications from the surgery. Death occurs in about 1 out of 200,000 healthy people who get anesthesia.¹

Some people who are going to have general anesthesia express concern that they will not be completely unconscious but will "wake up" and have some awareness during the surgical procedure. But awareness during general anesthesia is very rare. Anesthesia specialists devote careful attention and use many methods to prevent this.

Risks from reactions to anesthetic medicines

Some anesthetic medicines may cause allergic or other abnormal reactions in some people, but these are rare. If you suspect you may have such a problem, you should tell both your surgeon and anesthesia specialist well before your surgery. Testing will then be arranged as needed.

A rare, potentially fatal condition called malignant hyperthermia (MH) may be triggered by some anesthetics. The anesthetics most commonly associated with malignant hyperthermia include the potent inhalation anesthetics and the muscle relaxant succinylcholine. For more information, see the listing for the Malignant Hyperthermia Association of the United States (MHAUS) in the Other Places to Get Help section of this topic.

Recovering From Anesthesia

Recovery from anesthesia occurs as the effects of the anesthetic medicines wear off and your body functions begin to return. Immediately after surgery, you will be taken to a post-anesthesia care unit (PACU), often called the recovery room. There, nurses will care for and observe you. A nurse will check your vital signs and bandages and ask about your pain level.

How quickly you recover from anesthesia depends on the type of anesthesia you received, your response to the anesthesia, and whether you received other medicines that may prolong your recovery. As you begin to awaken from general anesthesia, you may experience some confusion, disorientation, or difficulty thinking clearly. This is normal. It may take some time before the effects of the anesthesia are completely gone.

Your age and general health also may affect how quickly you recover. Younger people usually recover more quickly from the effects of anesthesia than older people. People with certain medical conditions may have difficulty clearing anesthetics from the body, which can delay recovery.

After anesthesia

Some of the effects of anesthesia may persist for many hours after the procedure. For example, you may have some numbness or reduced sensation in the part of your body that was anesthetized until the anesthetic wears off completely. Your muscle control and coordination may also be affected for many hours following your procedure. Other effects may include:

• Pain. As the anesthesia wears off, you can expect to feel some pain and discomfort from your surgery. In some cases, additional doses of local or regional anesthesia are given to block pain during initial recovery. Pain following surgery can cause restlessness as well as increased heart rate and blood pressure. If you experience pain during your recovery, tell the nurse who is watching you so that your pain can be relieved.
• Nausea and vomiting. You may have a dry mouth and/or nausea. Nausea and vomiting are common after any type of anesthesia. It is a common cause of an unplanned overnight hospital stay and delayed discharge. Vomiting may be a serious problem if it causes pain and stress or affects surgical incisions. Nausea and vomiting are more likely with general anesthesia and lengthy procedures, such as surgery on the abdomen, the middle ear, or the eyes. In most cases, nausea after anesthesia does not last long and can be treated with medicines called antiemetics.
• Low body temperature (hypothermia). You may feel cold and shiver when you are waking up. A mild drop in body temperature is common during general anesthesia, because the anesthetic reduces your body's heat production and affects the way your body regulates its temperature. Special measures are often taken during surgery to keep a person’s body temperature from dropping too much (hypothermia).

Leaving the recovery area

When your normal body functions have returned, you either will be transferred to another location in the hospital to complete your recovery or allowed to go home.

In many cases minor surgical procedures are done on an outpatient basis. This means you will go home the same day. Before you are discharged from an outpatient clinic, you should be alert and able to understand and remember instructions. You will also want to make sure you have regained muscle control and coordination enough to walk safely, take fluids without vomiting, and take oral pain medicines safely. Depending on your medical history, your surgeon may also want you to be able to urinate before you are discharged.

When you are discharged, make sure you have:

• Reliable transportation to your home and for return to the hospital if complications develop. Do not plan to drive yourself home.
• A competent adult caregiver who can be with you for 24 hours after discharge.
• Access to a telephone so you can call for assistance if complications develop.
• Access to a pharmacy so you can get your prescriptions.

If you are not ready to go home, you will be transferred to another area in the hospital to complete your recovery. The length of your stay will depend on your response to your surgery.