What Happens During Anesthesia?
You likely will be given anesthesia by an anesthesia specialist. Final preparations before your surgery may include:
- Attaching instruments to check your breathing, oxygen level, heart rate, blood pressure, and other body functions.
- Positioning your body for surgery. You will be placed in a position that allows your surgeon access to the appropriate body area and avoids unnecessary pressure on any parts of your body.
The three main phases of anesthesia are induction, maintenance, and emergence.
The first phase of anesthesia, when you first begin receiving an anesthetic, is called induction.
For local anesthesia and many types of regional anesthesia, induction occurs when a local anesthetic is injected into the part of your body that needs to be anesthetized. Local and regional anesthesia often are given with other medicines that make you relaxed or sleepy (sedatives) or relieve pain (analgesics). These medicines are often given through a vein (intravenously, IV) before the local anesthetic is given.
Induction of epidural and spinal anesthesia may require the insertion of a needle into the space around the spinal nerves in the lower back. You will receive an injection of local anesthetic to reduce discomfort before the needle is inserted.
General anesthesia is often induced with IV anesthetics, but inhalation anesthetics also may be used.
- Because they enter directly into the bloodstream, intravenous anesthetics usually cause unconsciousness in less than 1 minute.
- Inhalation anesthetics also act quickly, but you must inhale them for a short time before they cause unconsciousness. Inhalation anesthetics are usually given through a mask that covers your nose and mouth. Induction with inhalation agents is mainly used for small children and adults who do not yet have an IV catheter.
Maintenance and monitoring
The second phase of anesthesia is called maintenance. During maintenance, the anesthesia specialist keeps a balance of medicines while carefully watching your breathing, heart rate, blood pressure, and other vital functions. Anesthesia is adjusted based on your responses during the procedure.
With local anesthesia and regional nerve blocks, maintenance frequently requires additional injections of sedatives to prolong the effects for more lengthy procedures.
For general anesthesia, after you are unconscious, anesthesia may be maintained with an inhalation anesthetic alone, with intravenous anesthetics, or most commonly with a combination of the two. Very often, inhalation anesthetics are given through an endotracheal (ET) tube or a laryngeal mask airway (LMA), which is an airway placed at the back of your throat but not in your windpipe like an ET tube. The airway is inserted after you become unconscious.
It also is common during general anesthesia for you to be given other medicines intravenously to maintain stable vital functions and to help prevent or decrease pain or nausea after the procedure.