Canadian Anesthesiologists' Society
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Anesthesia: General, Regional, Local


General anesthesia
William T. G. Morton became the first to publicly demonstrate the use of diethyl ether in October 1846as a general anesthetic at Massachusetts General Hospital, in what is known today as the Ether Dome.[61]

For more information on the origin of the discipline of anesthesia see - (http://en.wikipedia.org/wiki/History_of_general_anesthesia)

General anesthesia is a drug-induced, reversible state of unconsciousness, loss of memory, pain relief and relaxation of muscles.
For more information see - (http://en.wikipedia.org/wiki/Anesthesia)

Many people think that this involves the injection of just one drug. It certainly started out like that in the days of ether and chloroform. However, nowadays anesthesiologists practice balanced anaesthesia’. Different drugs, each with each own unique property, work together to provide general anesthesia. This allows us to use smaller doses of these very potent drugs. This practice together with major improvements in monitoring vital signs continuously, has made anesthesia very safe in 2010.

A typical general anesthetic given for gallbladder removal goes as follows.

Oxygen is administered constantly, initially with a mask over the face. All the patient's bodily functions are carefully controlled and monitored. First an intravenous injection of propofol to make the patient unconscious is given. This is followed by a muscle relaxant given to relax muscles of the abdomen to place a breathing tube and to ease the surgery. A morphine-like painkiller is now injected. A mixture of anesthetic gases (which always includes oxygen) is given through the breathing tube keep the patient unconscious throughout the whole surgery.

A mechanical breathing machine, called a ventilator, is attached. At the end of the operation, the effect of the muscle relaxants is reversed with two other drugs, and the anesthetic gases discontinued. When the patient is conscious and able to breathe without help, the ventilator is stopped and the breathing tube removed. All intravenous drugs and anesthetic gases are administered in appropriate amounts so that the patient is completely unconscious during the surgery, but awake and pain free at the end.

There are multiple variations on this basic technique - tailored to the surgery and medical condition of the patient.

Regional anesthesia

Regional anesthesia involves injecting local anesthetics close to a nerve or nerves that supplies feeling (and function) to the are of the body involved in the operation. The skin and tissues that the needle goes through are also numbed with local anesthetic so that there is minimal discomfort associated with placement of the needle. Local anesthetic drugs stop nerves from working temporarily, so that no sensation (and no pain !) and movement in the area of the body supplied by the nerve(s) occurs. This type of anesthesia is also called a nerve block.

The most common type of regional anesthesia is spinal anesthesia. This can be used to anesthetize the abdomen (‘belly’ area) and legs. Many other 'regions' of the body, such as an arm, can be safely and comfortably anesthetized. The effect of different local anesthetics lasts for different times, so the length of the anesthetic can be tailored to your operation. Epidural anesthesia is very similar to spinal, but as a small tube is left close to the nerves in the back. This allows the anesthesiologists or acute pain team to use the epidural to provide provide pain relief (called epidural analgesia) after your surgery.

You may remain completely awake if you wish, but usually your anesthesiologist will administer medication with a short duration to make you relaxed and comfortable during surgery. At the end of the operation patients are moved to the recovery room feeling awake, pain free and seldom ‘sick to the stomach’ They are usually very pleased with this type of anesthetic.

Please follow this link for more information on regional anesthesia (http://asra.com/patient-info.php)

Local anesthesia

Local anesthesia refers to temporarily numbing a small area by injecting local anesthetic into the skin so that minor procedures like stitching cuts can be done painlessly.


Written by:
Dr Martin van der Vyver (Specialist Anesthetist) MBChB FRCPC

Date created:

October 27, 2010