Modern surgery is possible because of the development of safe and effective anesthesia. Without the ability to eliminate pain, most surgical procedures could not be performed.
Anesthesia is administered by an anesthesiologist, a doctor who undergoes several years of specialized training after the completion of medical school. Anesthesia is sometimes administered by a certified registered nurse anesthetist (CRNA). A CRNA is a registered nurse who has undergone advanced training in anesthesia. Certified registered nurse anesthetists are able to administer anesthesia during a surgical procedure, but usually work under the supervision of an anesthesiologist.
- Type and length of the surgery
- Patient health
- Preference of the patient and physician
Local anesthesia blocks the nerves in a small, specific area of the body. For example, if a surgical procedure is performed on the right hand, a local anesthetic is used to numb that hand without affecting any other part of the body.
This type of anesthesia is generally used for minor surgeries (e.g., breast biopsies, vasectomies) and to stitch small wounds. It is usually administered by injection, which can be painful. However, the discomfort only lasts for a brief moment, and the anesthesia usually takes effect very quickly.
Sometimes local anesthesia is applied topically, as a spray or a cream. Cocaine is used medically as a sprayed anesthetic to numb the inside of the nose and throat. For the removal of a growth on the surface of the skin, an anesthetic cream can be applied to numb the area.
In minimally invasive procedures that can be completed in a few minutes, an injection of local anesthesia is all that is used. More involved operations require sedation with the anesthesia to make the patient more comfortable and the injection more tolerable. Sedatives relax the patient and induce drowsiness, but they do not put patients into a deep sleep. They are usually administered by injection or through an intravenous (IV), but can be given orally or by rectal suppository, particularly in children.
Regional anesthesia numbs a large area, or region, of the body and is used for more extensive and invasive surgery. Regional anesthesia is often used for procedures involving the lower part of the body, such as caesarian sections, prostate surgery, and operations on the legs. For example, if regional anesthesia is used for prostate surgery, the patient is numb from his navel to his toes. Some patients feel pressure or tugging during surgery performed under regional anesthesia.
The most common types of regional anesthesia are spinals and epidurals. Spinal anesthesia is injected into the spinal fluid with a special needle that penetrates the spinal column through the back. There may be some discomfort involved with the injection, but it passes as the anesthetic takes effect.
Epidural anesthesia is injected into an area outside the spinal column called the epidural space. Sometimes a small tube or catheter is inserted into the epidural space, which allows the anesthesiologist to administer more medication as needed. Epidurals are often used when long-term pain relief is needed, such as during childbirth.
Sedatives are commonly used with regional anesthesia and are generally administered intravenously.
General anesthesia renders the patient completely unconscious and with no memory of the surgical procedure upon awakening. Because it carries a higher risk for complications than other types of anesthesia, general anesthesia is used primarily for procedures that cannot be done utilizing other methods and for patients who prefer to be asleep during surgery.
General anesthesia is given intravenously or inhaled through a breathing mask, and sometimes both methods are used. Sedation may also be given before the patient is taken into the operating room.
Once the anesthesia has taken effect, patients need assistance breathing. Several devices are used. One is a piece of curved, hollow plastic called an oral airway. Another is a mask that fits over the nose and mouth. The most sophisticated device, a long plastic tube called an endotracheal tube, is placed in the patients mouth (less frequently the nose) and is gently extended into the trachea, or windpipe. The trachea connects the mouth with the lungs. The endotracheal tube is used when the surgery is lengthy or involved, and the patient receives a large amount of anesthesia. The endotracheal tube is one of the safest and most reliable means of assuring adequate breathing with general anesthesia.
Patients are closely monitored by the anesthesiologist throughout the surgery. Heart rate, blood pressure, and blood oxygen levels are continuously recorded. The amount of anesthesia received is carefully controlled and adjusted for the duration of the procedure.
When the operation is complete, the anesthesiologist reverses the anesthesia to allow the patient to wake up.