General anesthesia, regional anesthesia, monitored anesthesia care (“MAC”) are the three major categories of anesthesia available. General anesthesia effects the entire body, rendering it insensitive to pain and surgical stimulation. Regional anesthesia effects only a specific area of the body. Monitored anesthesia care is usually associated with intravenous sedation and vital signs monitoring.


Acting primarily on the brain and nervous system, general anesthesia is administered through the patient’s circulation system by injection or by inhalation. Since there is no one ideal general anesthetic, combinations of inhaled gas and injected drugs are usually given together.

Oxygen plus inhaled gas anesthetics are from an anesthetic machine to you by a face mask or plastic breathing tube inserted into the airway through the mouth or nose. Except in unusual circumstances, the breathing tube (endotracheal tube) is positioned after you are already asleep and removed prior to your full recovery of consciousness.

Modern gas anesthetics act rapidly through inhalation and their effects are rapidly reversible after surgery has been completed. Although most currently utilized gas anesthetics are not particularly offensive in odor, they are usually given following the initial administration of a rapidly acting and painless intravenous (IV) anesthetic drug that puts you to sleep.

After the initial injection of an IV anesthetic, anesthesia is maintained with inhaled gas anesthetics as additional anesthetic drugs continue to be given by IV.

General anesthesia is essential for extensive and longer surgical procedures but is appropriate for shorter and limited surgeries, too. Consciousness and awareness are completely lost with general anesthesia, and there is no sensation of pain.

See General Anesthetic Complications for information on possible risks.


Regional AnesthesiaUnlike general anesthesia, regional anesthesia does not act on the brain to produce a loss of consciousness or awareness. Even though no pain is experienced with a regional anesthetic, your Anesthesia Care Team member sometimes administers sedatives or tranquilizers through the IV to help with anxiety and apprehension. Though these drugs do not produce unconsciousness, they may leave you with little or no memory of the surgical procedure.

Regional anesthesia involves the loss of sensation in a limited area of a person’s body to prevent pain during a surgical procedure. This anesthesia is produced by drugs that temporarily interrupt the action of pain-carrying fibers.

There are several types of regional anesthesia and they include:

  • Local Anesthesia – The loss of pain sensation is produced by directly injecting the area to be treated. This is utilized primarily for minor surgery and closing wounds and incisions.
  • Spinal Anesthesia, Epidural Anesthesia and Caudal Anesthesia – These three techniques are quite similar in the effect that they produce. All involve the injection of a local anesthetic drug into the lower part of the back between the bony vertebrae. Spinal anesthesia involves placement of the anesthetic into the fluid surrounding the spinal cord. Epidural (caudal) anesthesia involves injection of the anesthetic in the epidural space just outside the spinal canal where the nerves leave the spinal cord. These anesthetics are most commonly used in obstetrics and surgical procedures of the lower abdomen, pelvis and lower extremities.
  • Nerve Blocks – involve the administration of anesthetic agents in the area of nerves to numb extremities or other parts of the body. To make administration of this “block” less painful, your Anesthesia Care Team member desensitizes the overlying skin with a local anesthetic. A sedative or analgesic (pain killer) may also be given.

Because regional anesthesia involves only a part of the body and doesn’t require one to be unconscious, it may be the preferred anesthetic in patients with diseases or physical conditions undesirably affected by general anesthesia.

See Side-effects and Complications of Regional Anesthesia for information on side-effects and complications.


MACMonitored Anesthesia Care (“MAC”) means that an Anesthesia provider is in attendance with you during your procedure or operation. Documentation and monitoring of your vital signs is performed so that interventions can be made if necessary. During the vast majority of “MAC” anesthetics you also will be given hypnotic and analgesic medications by your anesthesia team intravenously to make you more comfortable during the procedure. This has been referred to as “twilight sleep” by some. While patients may nap during the procedure, it is not unusual for them to wake up periodically and be aware of their surroundings. For surgical cases the surgeon will usually inject a local anesthetic into the surgical site to prevent or treat discomfort. “MAC” is most frequently utilized for relatively minor and peripheral procedures, or when it is felt that General or Regional Anesthesia is contraindicated because of health status or other factors.

Sometimes “MAC” may not involve giving you sedation at all. In these cases your Anesthesia provider has been asked by your surgeon or doctor to be present during your procedure or operation in case interventions are necessary, but not necessarily to sedate you. This may also occur for very ill patients for whom the response to even a little anesthetic drug may be exaggerated.