Anesthesiology And Types Of Anesthetic
Anesthetic is a substance capable of producing loss of sensation or sensitivity to pain.
There are two types of anesthetic. The local, or regional, anesthetic produces lack of feeling in a limited area of the body while the general anesthetic does the same for the whole body, producing total unconsciousness in the patient.
ANESTHESIOLOGY
The use of anesthetics is a complex branch of medicine known as anesthesiology. Much more is involved than simply giving an injection or administering ether.
A number of different chemicals may be used for general anesthesia during the same operation. One, for example, may be employed to produce unconsciousness quickly. Another may be needed to relax the muscles. Then, there is the substance which induces deep, prolonged sleep. All of these anesthetic agents must be kept in balance.
The anesthesiologist has a wide choice of anesthetics and methods of using them in surgical operations. He consults with the surgeon, and they choose those that are most likely to prove effective for the particular patient.
It is customary, before the operation, to acquaint the patient with the anesthetics and the procedure that will be used.
General Anesthesia
Ether (1) was once the most universally used of the general anesthetics, although it has now been largely replaced by others. In the usual procedure, the patient breathes the ether, which is delivered to him through tubes to a mask.
Another general anesthetic inhaled by the patient is Nitrous Oxide (laughing gas) (2). This is used in brief operations, such as in dentistry, and in childbirth, and may produce a feeling of exhilaration or put the patient to sleep.
Ethylene, Cyclopropane, and Halothane are general anesthetics now in wide use. Chloroform, which was developed well over 100 years ago, is not used extensively anymore because of undesirable side effects.
Anesthetics are also injected into the veins to produce quick, short-acting general anesthesia. Pentothal is used in this way.
Local Anesthesia
Probably the most familiar local anesthetic is Novacain, used in dentistry. The nerves surrounding the injection are deadened for one to two hours.
Some local anesthetics are applied to the surface of the skin or to mucous membrane. Benzocaine, for instance, is applied to wounds, and Tetracaine Hydrochloride to the nose and throat membranes.
Spinal anesthesia is local, but it can deaden sensation in very large areas of the body. It involves injecting an anesthetic into the space between vertebrae so that the spinal cord at this point is affected. The entire body below the point of injection becomes insensitive to pain, because no ‘pain messages’ can pass up to the brain.
When an anesthetic is injected in the lowest (caudal) area of the spine, the method is called caudal anesthesia (3).
Anesthesia in Childbirth
This presents special problems. First, there is a tendency for general anesthesia to induce some nausea and vomiting, with the danger of choking if the patient’s stomach is not empty. Because women in childbirth have not always had 12 hours or more warning not to eat, the anesthesiologist has to anticipate these complications.
Second, many forms of anesthesia enter the mother’s bloodstream and cross the placenta to the unborn child; therefore, anesthetics must be of the kind that does not seriously affect babies.
Third, anesthesia must not be so profound as to decrease birth contractions and so prolong labor unduly. For these reasons, doctors try to make minimal use of anesthetics for women in labor, reserving them for the relatively brief periods when pain is most severe and for repairs after delivery.
Demerol is the drug most commonly used to reduce first-stage labor pains. It is an analgesic, which does not interfere with consciousness, but produces a mildly euphoric state.
A more completely pain-eliminating anesthetic is the lumbar or caudal epidural block, an injection administered just outside the spinal canal, which removes almost all sensation in the uterus and vaginal region.
A general or spinal anesthesia is used in Cesarean Section deliveries, or where there are major complications.
During delivery, the vaginal area may be desensitized with a pudendal block, injections of anesthetic on either side of the vaginal opening; or with a local Novacain injection to deaden the tissue between the vagina and the rectum before an Episiotomy is performed.
New developments in anesthesia are being produced through continuous research. To name one advance, the temperature can be reduced in the part of the body to be operated on, so that the part loses its sensitivity.
Similarly, the temperature of the entire body may be lowered by an ice blanket. This slows down the body’s processes, decreasing the risk of hemorrhage in operations involving the circulatory system
REFERENCES
Ether in The Developing World: Rethinking An Abandoned Agent by Connie Y Chang et al (1)
Nitrous Oxide and The Inhalation Anesthetics by Daniel E Becker and Morton Rosenberg (2)
Caudal Anesthesia by Anterpreet Dua and Muriam Afzal (3)
Rich Health Editorial Team
Rich Health Editorial Team is made up of medical practitioners and experienced writers who provide information for dealing with health issues in a simple and easy-to-understand manner
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