A general anesthetic renders the patient asleep and insensitive to pain for surgery. Prior to beginning anesthesia, the anesthesiologist places monitors of blood pressure, electrocardiogram, pulse and oxygen saturation of the blood. Before the anesthetic, oxygen is administered by mask to fill the patient’s lungs with 100% oxygen. Most adult patients are given general anesthesia by intravenous injection, usually of the medication propofol. This injection causes the patient to lose consciousness within 10 - 20 seconds. This is called the induction of anesthesia. The maintenance of anesthesia during surgery is done by mixing an anesthesia gas or gases with the oxygen. Typical inhaled anesthesia gases are nitrous oxide, sevoflurane, or isoflurane. Sometimes a continuous infusion of intravenous anesthetic such as propofol is given as well. The choice and dose of drugs is done by the anesthesia attending, based on the patient’s size, age, the type of surgery, and the anesthesiologist’s experience.

Many patients are given prophylactic anti-nausea medication during the anesthetic. If postoperative pain is anticipated, the anesthesiologist can also administer intravenous narcotics such a
morphine, meperidine (Demerol), or fentanyl.

Depending on the patient’s medical condition and type of surgery, the anesthesiologist may protect the patient’s airway during the general anesthetic by placing a breathing tube through the mouth, either an endotracheal tube (ET Tube) into the patient’s windpipe, or a laryngeal mask airway (LMA) just above the voice box.

At the conclusion of surgery, the general anesthetic gases and/or intravenous anesthetic infusion(s) are discontinued. The patient usually regains consciousness within 5 - 15 minutes. The patient is then transferred to the recovery room (see After Surgery).
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