Anesthesia

General anesthesia is the induction of a state of unconsciousness with the absence of pain sensation over the entire body, through the administration of anesthetic drugs. It is used during certain medical and surgical procedures.

Purpose

General anesthesia has many purposes including:

1. pain relief (analgesia)
2.  blocking memory of the procedure (amnesia )
3.  producing unconsciousness
4.  inhibiting normal body reflexes to make surgery safe and easier to perform
5.  relaxing the muscles of the body

Anesthesia performed with general anesthetics occurs in four stages which may or may not be observable because they can occur very rapidly:

1. Stage One: Analgesia. The patient experiences analgesia or a loss of pain sensation but remains conscious and can carry on a conversation.
2. Stage Two: Excitement. The patient may experience delirium or become violent. Blood pressure rises and becomes irregular, and breathing rate increases. This stage is typically bypassed by administering a barbiturate, such as sodium pentothal, before the anesthesia.
3. Stage Three: Surgical Anesthesia. During this stage, the skeletal muscles relax, and the patient's breathing becomes regular. Eye movements slow, then stop, and surgery can begin.
4. Stage Four: Medullary Paralysis. This stage occurs if the respiratory centers in the medulla oblongata of the brain that control breathing and other vital functions cease to function. Death can result if the patient cannot be revived quickly. This stage should never be reached. Careful control of the amounts of anesthetics administered prevent this occurrence.

Recommended dosage

The dosage depends on the type of anesthetic, the patient's age and physical condition, the type of surgery or medical procedure being done, and other medication the patient takes before, during, or after surgery.

Precautions

Although the risks of serious complications from general anesthesia are very low, they can include heart attack, stroke, brain damage, and death. Anyone scheduled to undergo general anesthesia should thoroughly discuss the benefits and risks with a physician. The risks of complications depend, in part, on a patient's age, sex, weight, allergies, general health, and history of smoking, drinking alcohol, or drug use. Some of these risks can be minimized by ensuring that the physician and anesthesiologist are fully informed of the detailed health condition of the patient, including any drugs that he or she may be using. Older people are especially sensitive to the effects of certain anesthetics and may be more likely to experience side effects from these drugs.

Patients who have had general anesthesia should not drink alcoholic beverages or take medication that slow down the central nervous system (such as antihistamines, sedatives, tranquilizers, sleep aids, certain pain relievers, muscle relaxants, and anti-seizure medication) for at least 24 hours, except under a doctor's care.

Before being given a general anesthetic, a patient who has any of the following conditions should inform his or her doctor:

1. neurological conditions, such as epilepsy or stroke
2. problems with the stomach or esophagus, such as ulcers or heartburn
3. eating disorders
4. loose teeth, dentures, bridgework
5. heart disease or family history of heart problems
6. lung diseases, such as emphysema or asthma
7. history of smoking
8. immune system diseases
9. arthritis or any other conditions that affect movement
10. diseases of the endocrine system, such as diabetes or thyroid problems
11. Allergies
12. Pregnancy
13. Breastfeeding

Side effects

Because general anesthetics affect the central nervous system, patients may feel drowsy, weak, or tired for as long as a few days after having general anesthesia. Fuzzy thinking, blurred vision, and coordination problems are also possible. For these reasons, anyone who has had general anesthesia should not drive, operate machinery, or perform other activities that could endanger themselves or others for at least 24 hours, or longer if necessary.

Most side effects usually disappear as the anesthetic wears off. A nurse or doctor should be notified if these or other side effects persist or cause problems, such as:

1. Headache
2. vision problems, including blurred or double vision
3. shivering or trembling
4. muscle pain
5. dizziness, lightheadedness, or faintness
6. drowsiness
7. mood or mental changes
8. nausea or vomiting
9. sore throat
10. nightmares or unusual dreams

A doctor should be notified as soon as possible if any of the following side effects occur within two weeks of having general anesthesia:

1. severe headache
2. pain in the stomach or abdomen
3. back or leg pain
4. severe nausea
5. black or bloody vomit
6. unusual tiredness or weakness
7. weakness in the wrist and fingers
8. weight loss or loss of appetite
9. increase or decrease in amount of urine
10. pale skin
11. yellow eyes or skin