How General Anesthesia Works

General anesthesia is a drug-induced loss of consciousness during which you are not arousable, even by painful stimulation. Multiple types are available. Some allow you to be alert and oriented during a medical procedure, while others make sleep so you're unaware of what's going on.

The type of anesthesia you get depends on the nature of the procedure being performed, your age and overall health, and the preferences of the surgeon and anesthesia provider. With some procedures, you may be able to choose between different types of anesthesia, while other procedures require a specific type.

What Is General Anesthesia?

General anesthesia is the strongest type and the one most frequently used during surgery. It essentially puts you into a medically induced coma.

Typically used during surgery, general anesthesia allows a healthcare provider to provide treatments that would be extremely painful if the person were awake and able to feel.

Sometimes, it even involves using medication to paralyze the body's muscles, including those that make breathing possible. For this reason, people who receive general anesthesia require a ventilator to do the work of the diaphragm and other muscles that help make it possible to inhale and exhale.

Uses of General Anesthesia

General anesthesia is typically used for more serious surgeries, lengthy procedures, and procedures that would typically be very painful. This type of anesthesia not only allows a person to undergo a procedure without pain but also allows the person to be unconscious for the procedure.

For some surgeries, it would be very traumatic to be awake for the procedure, whether or not you were able to feel pain. Imagine having a body part such as your appendix removed, and being wide awake. While you might not feel any pain, it could still be extremely distressing.

Risks of General Anesthesia

The risks associated with anesthesia vary widely from procedure to procedure, and from person to person. Everyone has their own individual risk level, as no two people are exactly the same.

For example, a 90-year-old person with chronic illnesses will have a completely different level of risk than a healthy 12-year-old, even if they're having the same procedure.

Some risks that may be experienced while under anesthesia include:

• Anesthesia awareness: This is a condition that occurs when the person isn’t completely unconscious during general anesthesia. This has an incidence rate of 0.2%.
• Aspiration: It's possible to inhale food or fluids that may be vomited up during surgery, which is why you're told not to eat for several hours before surgery.
• Pneumonia or other breathing problems: These increase with age and long surgery duration and are believed, at least in part, due to the deep muscle relaxation that occurs. Abdominal surgeries may also carry a higher risk.
• Corneal abrasions: Scratches to the eye are a risk, and may occur due to a variety of causes.
• Dental injury: These may be caused by laryngoscope or endotracheal tube placement.
• Malignant hyperthermia: This is a potentially life-threatening condition that causes a severe reaction to anesthesia. It typically runs in families.
• Cardiovascular problems: These can include heart attack, heart failure, stroke, and abnormally high or low blood pressure.
• Death (rare): According to some research, nearly half of anesthesia-related deaths are due to anesthesia overdose. Most others are due to adverse reactions to the anesthetics, including malignant hyperthermia and breathing problems. The risk, while small, increases with age.

Some risks and side effects come after the procedure is over, including:

• Nausea and vomiting: This is the most common issue people face after general anesthesia. If you have a history of nausea caused by anesthesia, tell your healthcare provider. You may be able to take medications to prevent it, and preventing it is typically easier than treating it.
• Shivering and chills: This typically lasts for a short time after surgery and goes away once you're awake and moving.
• Muscle aches: Caused by the medication or by lying still during a procedure, this condition is typically temporary and goes away within hours or days of having surgery.
• Itching: Pain medication, including anesthesia, is often to blame for itching. Painkillers you're given after surgery can cause it, as well. It typically goes away once the medication is out of your system.
• Difficulty urinating: This is more common in people who have a urinary catheter during surgery and it can take hours or even days for the bladder to return to normal.
• Sore throat and hoarseness: Caused by the breathing tube, this irritation is typically minor.
• Dry mouth: This is generally a minor issue that goes away when you're able to drink fluids again.
• Sleepiness: This is common after surgery and resolves when the body has eliminated most of the anesthesia medications.
• Confusion: This is most common in elderly people and in those who have Alzheimer’s disease, dementia, or another condition that contributes to confusion.
• Ileus: This is a condition where the intestines do not wake as quickly as expected after surgery and movement is very slow or is absent.
• Difficulty getting off the ventilator: Weaning from the ventilator is more challenging in those who are very sick or who have a breathing problem.
• Blood clots: This issue is more common after surgery because the person is still for an extended period of time, which is a known risk factor for blood clots.

Other Types of Anesthesia

Before you decide that you need general anesthesia for your procedure, it is important to know the different types of anesthesia that are available. The other most common types of anesthesia are:

• Regional anesthesia: Also known as a regional block, this type of anesthesia prevents the person from feeling a region of the body, such as an entire arm or below the waist.
• Local anesthesia: This type of anesthesia prevents feeling in a small area of the body, such as when a finger is numbed so that stitches can be used to sew a cut closed.
• Monitored anesthesia care (MAC): This type of anesthesia, also known as twilight sleep, is a type of anesthesia that prevents pain while the person is conscious or lightly sedated. The person may remember the entire procedure or may have no recall of events.

During General Anesthesia

The process of general anesthesia often starts with sedation, to make it possible to insert a breathing tube. The type of sedation is left to the anesthesia provider to choose and can vary widely depending upon the person and the type of surgery.

Once you're in the operating room, attached to the monitoring devices, and the safety protocols have been completed, anesthesia can begin.

It is common practice that before sedating medications are given, a "time out" is done in which the medical team verifies your identity and the procedure you're having. This is done to prevent errors such as the wrong surgery being performed.

Once the time out is completed, you can be given sedating medication and the anesthesia provider starts preparing you for surgery.

Intubation and Ventilation

Often, the muscles of the body are paralyzed during general anesthesia, including the muscles that help the lungs draw breaths, which means the lungs are unable to function on their own.

For this reason, you'll be hooked up to a ventilator that will take over the job of inhaling for your lungs. To be clear, the lungs still work during anesthesia, they just can't draw breath because the muscles that do that work are temporarily disabled.

Being placed on a ventilator requires that a tube, called an endotracheal tube, be inserted into your airway. This tube is then attached to larger tubing that goes to the ventilator, allowing the ventilator to deliver oxygen to you.

The process of inserting the tube is called intubation. People are anesthetized prior to inserting a breathing device.

Monitoring

During surgery, the patient is monitored very closely by electronic monitoring devices that track heart rate, the amount of oxygen in the blood, the number of breaths taken, and even an electrocardiogram (EKG). In addition to electronic monitoring, the patient is also monitored by the operating-room staff and the anesthesia provider.

General anesthesia is typically provided by either a physician anesthetist (called an anesthesiologist) or a certified registered nurse anesthetist (CRNA). Both provide safe and effective anesthesia and have extensive experience in providing general anesthesia.

During the procedure, the goal is for you to be completely unaware of what is happening and to be without pain.

How Do They Wake You Up From Anesthesia?

How you wake from anesthesia depends on the type of surgery you had and how well you're breathing. The goal after general anesthesia is to extubate the person—remove the breathing tube—as quickly as possible after surgery ends.

At the end of the procedure, when the procedure is common and uncomplicated, you'll typically be given medications that reverse anesthesia, waking you up and ending the muscle paralysis. Then the breathing tube can come out right away and you'll be breathing on your own within minutes.

When procedures are longer, reversal agents are still given prior to extubation. In this situation, you'll wake in the PACU—post-anesthesia care unit—and move to a hospital room or go home once you're completely awake. People typically will have pain in the recovery phase, which is managed.

For some very serious surgeries, such as open-heart surgery or brain surgery, the person is allowed to slowly wake from anesthesia with no reversal agent to bring the muscles out of paralysis. This means the person may remain on the ventilator until they're fully conscious, which can be between six and eight hours after surgery.

Some people may have to stay on a ventilator for days or even longer after surgery, but this is less common. It happens most often with people with certain risk factors, including respiratory diseases, smoking, and obesity.

Eating and Drinking After Anesthesia

Once you're awake after surgery, you may be able to suck on ice chips or take sips of water. If this goes well, the next step is to drink regular liquids, followed by a regular diet.

This process can take hours, or even days if the person experiences nausea, vomiting, or just doesn’t feel up to taking food or fluids. In most cases, people are able to eat regular foods within a day of having general anesthesia.

Safety After General Anesthesia

The American Association of Nurse Anesthetists (AANA) makes multiple recommendations for patient safety after receiving general anesthesia. This is because it can take a full day or longer to have anesthesia completely wear off, and until it does, the average person may find themselves feeling sleepy, nauseated, or even confused.

For at least the first 24 hours after surgery:

• Expect to spend most of the time resting quietly, napping, or doing relaxing activities.
• Stay home from work.
• Avoid challenging activities.
• Don't operate heavy machinery—including driving a car, so you may need to arrange for a ride home.
• Don't sign any legal paperwork.
• Avoid alcohol or sedating medications not prescribed by your surgeon.
• If you have young children, find help with child care.

A Word From Verywell

General anesthesia does have risks, but the rewards of having a pain-free surgery can be substantial. Your decision to have surgery should weigh the risks of the procedure and the anesthesia you will receive against the potential rewards.