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When the surgeon is ready for the patient to be anesthetized, the anesthetic induction is begun. For adults, this is usually accomplished with a series of medications given through the IV. These medications are referred to as induction agents, so named because they induce or bring about the state of anesthesia. For small children, in whom establishing IV access can be more difficult while awake, anesthesia is often induced by administering inhalational agents, or gases, by means of a mask placed over the mouth and nose. If needed, the IV is then placed after the child is asleep. Although the induction agents begin the anesthetic, they are not usually all that is used. Their value is in quickly establishing the anesthetized state. During general anesthesia the entire body, including the brain, is put to sleep. Under this type of anesthetic the patient feels nothing during the operation and remembers nothing about the procedure.Induction agents are frequently used to anesthetize the patient for what is called endotracheal intubation. This is the act of placing a breathing tube, usually through the mouth, past the vocal cords and into the trachea, or windpipe. Once this has been accomplished, longer-acting agents are given IV and anesthesia gases may be administered through the tube.
After proper tube placement, the anesthesia for the surgery is begun. Typically this consists of inhalational agents delivered through the breathing tube plus narcotic and muscle-relaxing drugs given IV. Each agent plays its own role in producing anesthesia. The inhalational agents, or gases, seem to affect the membranes of nerve cells. They appear to reduce nerve cell activity and thus decrease awareness and memory; narcotics blunt the perception of pain; and muscle relaxants, though not always required, are often used to facilitate the surgery by making it easier for the surgeon to separate muscle layers and gain the needed exposure.
The anesthesia is continued in this manner until the completion of surgery, at which time the gases are discontinued and if necessary the effects of the muscle relaxants are antagonized or "reversed" with IV medications. When the patient has regained sufficient strength and responsiveness, the breathing tube is removed and the patient is transferred to the recovery room for monitoring. Most persons are awake enough to be responsive and cooperative soon after arrival in recovery, although their memory of events may lag behind somewhat. |
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