There are many forms of anaesthesia, and many different means of administering them, including IV injections, tablets, and inhalation of medication in gas form. There are many types of anaesthesia as well, distinguished by how narrow or wide their effects. The main types include local anaesthesia, regional anaesthesia, sedation and general anaesthesia.
Depending on the type used, anaesthesia can help you relax, make you feel drowsy, prevent you from feeling restless or uncomfortable during long procedures or put you to sleep, all while keeping you from consciously feeling pain. By consciously, we mean whether you feel pain or not. When you are unconscious (general anaesthesia), your brain feels pain, but your body is unaware of it. Local anaesthetics stop your brain from receiving the message entirely.
In this article we describe the different types of anaesthesia, what they are used for, how they are administered and their potential advantages and disadvantages.
Local anaesthesia is used to prevent pain and loss of blood in very specific areas during a treatment or procedure. For example, your dentist injects a local anaesthetic into your gum near a tooth before a tooth extraction. When local anaesthesia is used, the patient is awake and aware of what is going on. The anaesthetic blocks the electrical impulses sent by nerves from reaching the brain. It does not affect the brain, only the nerve endings in the area within its reach. Local anaesthesia can be administered as a spray, gel, ointment, drops or as an injection.
Although complications are rare with local anaesthesia, there is always the risk that the medication can be absorbed into your body, leading to either allergies or overdosing.
Local anaesthetics typically fall into the chemical groups of amides or esters. Amides are metabolised by the liver and rarely or never cause allergies, although they may cause other types of reactions. Esters are metabolised by enzymes in the blood to a compound similar to PABA (para-amino-benzoic-acid), an allergenic frequently found in sunscreen and cosmetics. Those who are allergic to PABA need to inform this fact to their anaesthesiologist. Severe overdosing may cause seizures lasting between 15 to 30 seconds. Your surgeon and anaesthesiologist will consider this a medical emergency and treat you accordingly. Anaesthesiologists take precautions against overdose by not exceeding the medically recommended doses for anaesthetic drugs, injecting slowly and closely observing their patients in the first five to ten minutes following the injection.
The infusion of other medications along with anaesthesia can prevent blood loss in cosmetic procedures such as liposuction.
Think of regional anaesthesia as a local anaesthetic with a wider area of impact. Regional anaesthetics work by preventing nerve signals over a large area, often blocking entire nerve clusters. Like local anaesthesia, regional anaesthesia also does not affect the brain directly, only the individual nerve endings in a wide area.
Different forms of regional anaesthetics are used under specific conditions or when operating on certain parts of the body. For example, a spinal anaesthetic is administered by injecting a single dose of anaesthetic directly into the fluid that surrounds the spinal cord in the lower back. It causes numbness in the lower body. Spinal anaesthetics are used for pelvic, rectal, lower abdominal or leg surgery.
Epidural anaesthetics are similar to spinal anaesthetics and are commonly used when operating on the legs and during childbirth. However, instead of a single-dose injection, the epidural anaesthetic is administered by infusing medication continually through a thin catheter placed into the epidural space of the spinal column in the lower back. The final result is the same: numbness in the lower body.
Regional anaesthetics are often referred to as nerve blocks, and more specifically as spinal or epidural blocks.
Peripheral nerve blocks are injected near a cluster of nerves to numb extremities of the body, such as the arms, legs or the head. A femoral nerve block is produced by injection into the leg. A brachial plexus block is produced by injection in the arm and shoulder region. These blocks are commonly used during surgery on the knee, shoulder or arm.
Depending on the type of procedure and your needs, you may remain conscious during the procedure. Light, moderate or deep sedation can be administered together with regional anaesthetics as needed. Regional anaesthesia generally provides better pain control than narcotics and causes less nausea.
Sometimes complications and side effects occur despite your anaesthesiologist taking special precautions to avoid them. For regional anaesthesia, these can include drops in blood pressure, spinal headaches, which may occur afterwards, and soreness or tenderness around the area where the anaesthetic was administered.
People who have undergone spinal or epidural anaesthesia sometimes develop a headache as a result of spinal fluid leaking out when the dural sac is punctured during the process. These are referred to as spinal headaches, and may be experienced when standing or sitting. Most commonly they occur within 3 to 5 days following the procedure and are experienced with differing levels of severity and pain. Contact your surgeon immediately if you have a headache after a spinal or epidural anaesthetic.
Administering additional fluids into the system may control a drop in blood pressure. Discomforts such as soreness and tenderness will disappear within a few days. If they persist or get worse, your doctor may provide additional treatments to provide relief.
Sedation is a broad-spectrum anaesthetic in which patients are given a chemical cocktail to make them sleepy or drowsy. Sedatives affect the brain directly. While sedation does not render people completely unconscious, the chemical mix is strong enough to take the patient to the very edge of unconsciousness. Sedative drugs can be administered intravenously, orally or as an inhaled gas.
Sedation can be minimal, moderate or deep. With minimal sedation, a person feels relaxed but remains awake, can understand the doctor’s questions and respond with answers or follow instructions. Moderate sedation makes people drowsy. Some patients fall asleep, but can be awakened easily. They may or may not remember what occurs while under moderate sedation. People sleep through deep sedation and are completely unaware of what occurs during that time. Breathing slows down and patients usually continue to sleep until the effects of the medication wear off.
When higher doses are administered, sedation is similar to general anaesthesia and brings about total unconsciousness. To ensure patient safety, monitoring by a qualified anaesthesiologist is essential at this level of sedation. When sedatives are introduced directly to the bloodstream (as IV), it is possible to keep the level of medication constant.
Common side effects of sedation include headaches, nausea and vomiting.
General anaesthesia employs medications that directly affect the brain to bring about a state of total unconsciousness. In effect, general anaesthesia puts the patient into a medically induced coma. It is most commonly administered by a combination of intravenous drugs and inhaled anaesthetic gases.
People do not remember what happens while they are under general anaesthesia. Nor do they feel pain, even though their brain still registers those pain sensations. How exactly general anaesthesia works is still not completely clear, but we know that it relaxes the muscles and slows down the functions of the brain.
General anaesthesia is used for procedures that take a long time, may interfere with breathing—as in upper abdominal or chest surgery—or require the patient to be in an uncomfortable position for a long period. While under general anaesthesia, breathing and vital body functions are monitored closely by a specially trained physician known as an anaesthesiologist. A certified registered nurse anaesthetist may also be present.
Most healthy people do not encounter any problems with general anaesthesia. As with any medical procedure, however, there is a low-level risk of long-term complications. Factors that can increase your risk of complications include medical conditions involving the heart, lungs or kidneys, and medications that can increase bleeding, such as aspirin. Smoking increases your level of risk due to potential breathing problems, and alcohol use may put you at a higher risk of liver damage. Food or drug allergies or a history of adverse reactions to anaesthesia running in your family may require special precautions and should be disclosed to your anaesthesiologist and the medical team. Medical conditions such as sleep apnoea and obesity can also lead to complications. Complications such as temporary mental confusion, lung infections, heart attacks, stroke and death are very rare. They occur mostly in older adults or people with medical problems.
That depends on many factors:
It is your duty to inform your surgeon and anaesthesiologist of your general health, medical history, any medical conditions and any medications you are taking. Certain risks associated with anaesthetics can be avoided if your doctors are fully informed in advance about the factors mentioned above.
You can learn more about which types of anaesthesia are used for different cosmetic procedures in Part 2 of this article series: Types of Anaesthesia for Cosmetic Surgery – Part 2.