Anaesthesia: what it is, when it is performed and what functions it performs

Anesthesia is a treatment using drugs called anesthetics. These drugs keep you from feeling pain during medical procedures

Anesthesiologists are medical doctors who administer anesthesia and manage pain

Some anesthesia numbs a small area of the body.

General anesthesia makes you unconscious (asleep) during invasive surgical procedures.

What is anesthesia?

Anesthesia is a medical treatment that keeps you from feeling pain during procedures or surgery.

The medications used to block pain are called anesthetics.

Different types of anesthesia work in different ways.

Some anesthetic medications numb certain parts of the body, while other medications numb the brain, to induce a sleep through more invasive surgical procedures, like those within the head, chest, or abdomen.

How does anesthesia work?

Anesthesia temporarily blocks sensory/pain signals from nerves to the centers in the brain.

Your peripheral nerves connect the spinal cord to the rest of your body.

Who performs anesthesia?

If you’re having a relatively simple procedure like a tooth extraction that requires numbing a small area, the person performing your procedure can administer the local anesthetic.

For more complex and invasive procedures, your anesthetic will be administered by a physician anesthesiologist.

This medical doctor manages your pain before, during and after surgery.

In addition to your physician anesthesiologist, your anesthesia team can be comprised of physicians in training (fellows or residents), a certified registered nurse anesthetist (CRNA), or a certified anesthesiologist assistant (CAA).

What are the types of anesthesia?

The anesthesia your healthcare provider uses depends on the type and scope of the procedure.

Options include:

  • Local anesthesia: This treatment numbs a small section of the body. Examples of procedures in which local anesthesia could be used include cataract surgery, a dental procedure or skin biopsy. You’re awake during the procedure.
  • Regional anesthesia: Regional anesthesia blocks pain in a larger part of your body, such as a limb or everything below your chest. You are can be conscious during the procedure, or have sedation in addition to the regional anesthetic. Examples include an epidural to ease the pain of childbirth or during a cesarean section (C-section), a spinal for hip or knee surgery, or an arm block for hand surgery.
  • General anesthesia: This treatment makes you unconscious and insensitive to pain or other stimuli. General anesthesia is used for more invasive surgical procedures, or procedures of the head, chest, or abdomen.
  • Sedation: Sedation relaxes you to the point where you will have a more natural sleep, but can be easily aroused or awakened. Light sedation can be prescribed by the person performing your procedure, or together with a regular nurse, if they both have training to provide moderate sedation. Examples of procedures performed with light or moderate sedation include cardiac catheterization and some colonoscopies. Deep sedation is provided by an anesthesia professional because your breathing may be affected with the stronger anesthetic medications, but you will be more asleep than with light or moderate sedation. Although you won’t be completely unconscious, you are not as likely to remember the procedure.

How is administered?

Depending on the procedure and type of anesthesia needed, your healthcare provider may deliver the anesthesia via:

  • Inhaled gas.
  • Injection, including shots or intravenously (IV).
  • Topical (applied to skin or eyes) liquid, spray or patch.

How should I prepare for?

Make sure your healthcare provider has a current list of the medications and supplements (vitamins and herbal medications) you take.

Certain drugs can interact with anesthesia or cause bleeding and increase the risk of complications.

You should also:

  • Avoid food and drinks for eight hours before you go to the hospital unless directed otherwise.
  • Quit smoking, even if it’s just for one day before the procedure, to improve heart and lung health. The most beneficial effects are seen with no smoking for two weeks before.
  • Stop taking herbal supplements for one to two weeks before the procedure as directed by your provider.
  • Not take Viagra® or other medications for erectile dysfunction at least 24 hours before the procedure.
  • You should take certain (but not all) blood pressure medications with a sip of water as instructed by your healthcare provider.

What happens during anesthesia?

A physician anesthesiologist:

  • Administers one type or a combination of anesthetics listed above pain therapies, and possibly anti-nausea medications.
  • Monitors vital signs, including blood pressure, blood oxygen level, pulse and heart rate.
  • Identifies and manages problems, such as an allergic reaction or a change in vital signs.
  • Provides postsurgical pain management.

What should I do after getting anesthesia?

For procedures using local anesthesia, you can return to work or most activities after treatment unless your healthcare provider says otherwise.

You’ll need more time to recover if you’ve received regional or general anesthesia or sedation.

You should:

  • Have someone drive you home.
  • Rest for the remainder of the day.
  • Not drive or operate equipment for 24 hours.
  • Abstain from alcohol for 24 hours.
  • Only take medications or supplements approved by your provider.
  • Avoid making any important or legal decisions for 24 hours.

What are the potential side effects?

Most anesthesia side effects are temporary and go away within 24 hours, often sooner.

Depending on the anesthesia type and how providers administer it, you may experience:

  • Back pain or muscle pain.
  • Chills caused by low body temperature (hypothermia).
  • Difficulty urinating.
  • Fatigue.
  • Headache.
  • Itching.
  • Nausea and vomiting.
  • Pain, tenderness, redness or bruising at the injection site.
  • Sore throat (pharyngitis).

What are the potential risks or complications of anesthesia?

Every year, millions of Americans safely receive anesthesia while undergoing medical procedures. However, anesthesia does carry some degree of risk.

Potential complications include:

  • Anesthetic awareness: For unknown reasons, about one out of every 1,000 people who receive general anesthesia experience awareness during a procedure. You may be aware of your surroundings but unable to move or communicate.
  • Collapsed lung (atelectasis): Surgery that uses general anesthesia or a breathing tube can cause a collapsed lung. This rare problem occurs when air sacs in the lung deflate or fill with fluid.
  • Malignant hyperthermia: People who have malignant hyperthermia (MH) experience a dangerous reaction to anesthesia. This rare inherited syndrome causes fever and muscle contractions during surgery. It is important to relate a personal or family history of MH to your physician anesthesiologist before your anesthetic to avoid drugs that trigger this reaction.
  • Nerve damage: Although rare, some people experience nerve damage that causes temporary or permanent neuropathic pain, numbness, or weakness.
  • Postoperative delirium: Older people are more prone to postoperative delirium. This condition causes confusion that comes and goes for about a week. Some people experience long-term memory and learning problems. This condition is known as postoperative cognitive dysfunction.

Who is at risk for anesthesia complications?

Certain factors make it riskier to receive anesthesia, including:

  • Advanced age.
  • Diabetes or kidney disease.
  • Family history of malignant hyperthermia (anesthesia allergy).
  • Heart disease, high blood pressure (hypertension) or strokes.
  • Lung disease, such as asthma or chronic obstructive pulmonary disease (COPD).
  • Obesity (high body mass index or BMI).
  • Seizures or neurological disorders.
  • Sleep apnea.
  • Smoking.

How long does it take to recover from anesthesia?

Anesthetic drugs can stay in your system for up to 24 hours.

If you’ve had sedation or regional or general anesthesia, you shouldn’t return to work or drive until the drugs have left your body.

After local anesthesia, you should be able to resume normal activities, as long as your healthcare provider says it’s okay.

When should I call the healthcare provider?

You should call your healthcare provider if you’ve had anesthesia and experience:

  • Difficulty breathing.
  • Extreme itching, hives or swelling.
  • Numbness or paralysis anywhere in your body.
  • Slurred speech.
  • Trouble swallowing.

How does anesthesia affect pregnancy?

Local anaesthesia affects a small area of the body. It’s considered safe for pregnant or breastfeeding women.

Many pregnant women safely receive regional anesthesia, such as an epidural or spinal block, during childbirth.

Your healthcare provider may recommend postponing elective procedures that require regional or general anesthesia until after childbirth.

How does anesthesia affect breastfeeding?

This is considered safe for breastfeeding mothers and their babies.

Medications used in all types of anesthesia, including general anesthesia, leave the system quickly.

It is often recommended for patients to express their first breast milk after a general anesthetic before resuming breast feeding their infant.


  • American Association of Nurse Anesthetists. All About Anesthesia. ( Accessed 9/29/2020.
  • American Society of Anesthesiologists. Anesthesia 101. ( Accessed 9/29/2020.
  • National Institute of General Medical Sciences. Anesthesia. ( Accessed 9/29/2020.

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