All About General Anesthetics And How They Are Used

By Lila Barry


General anesthetics are often administered to patients prior to surgery in order to induce a complete loss of sensation and consciousness. While it is not totally understood how these medications work, there are a few speculations. The common thread found in each of these theories is that the drugs disrupt the function of the receptor cells in the nervous system, thus preventing the sensation of pain.

There are two possible ways to administer a general anesthetic, intravenously or though inhalation. In most cases a combination of the two methods is used. A doctor called an anesthetist will administer the anesthetic and monitor it closely during the surgery, afterwards it will be reversed and the patient will become conscious.

An anesthesia machine is used to deliver inhaled gases or liquids which are vaporized and combined with air and oxygen, and sometimes nitrous oxide to the patient by way of a breathing mask. The machine also monitors the patient's response to the drug and controls its levels. The most commonly used inhaled compounds include Desflurane, Sevoflurane, and Isoflurane.

The injectable form of anesthetics generally work faster and are effective for inducing unconsciousness and maintaining it through a constant intravenous drip. Drugs such as Propofol and Etomidate are some of the most common ones used in IV drips for general anesthesia. Sometimes benzodiazepines are given at the same time to bring about a sedative effect.

Surgeries which are more complex procedures that typically take a longer time to complete are usually best suited to using a general anesthetic as opposed to a local. This will be decided by the patient and his or her anesthetist. Some operations which normally always use a general include gallbladder removal, hysterectomy, hernia repair, and appendectomy.

As there are some rare but possible risks associated with anesthesia, the anesthetist will first ask the patient some questions about his or her health history. Most complications are seen in obese patients, heavy drinkers or smokers, or those with unusual allergic reactions. It is also important to always follow the instructions given by the doctor too, such as not eating for several hours before surgery as to avoid the possibility of vomiting and aspirating.

Anesthesia has four stages. The first involves the induction of unconsciousness. The second stage is known as the REM stage. The third stage is termed "surgical anesthesia" and is characterized by constriction of the pupils, relaxation of the muscles, and regular breathing, this is the most stable stage during which the surgery will be performed. Stage four is to be avoided, as it is classified as overdose of the compounds administered and may be fatal if not reversed.

As the patient is undergoing surgery, his or her vital signs will need to be carefully monitored by medical personnel. It is normal for there to be some side effects immediately after the patient is revived such as dizziness, nausea, chills, and a sore throat from the breathing tube which was inserted. After a few hours these feelings will usually subside however. Overall, the benefits of general anesthetics are greater than the discomforts associated with it.




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