Local anesthesia involves injection into a surgical site, but the patient remains awake. Regional anesthesia numbs a large area of the body while the patient remains awake. Perhaps the most widely recognized use is an epidural to make childbirth more comfortable for women.
And researchers are really just starting to gain a sense of how different medications used to numb or induce unconsciousness work. They think the drugs target different proteins in the membranes around nerve cells.
Propofol is one of the most common medications used for general anesthesia. A study focused specifically on propofol to dig into what mechanisms are at play. The research found this type of anesthesia restricts movement of a type of protein in a way that inhibits communication between neurons. And remember, different drugs achieve different results. The question of how anesthesia works is further complicated by the fact that different types often need to be used in combination with each other.
A single medication may not be sufficient for a given procedure. Ma points out. Anesthesia is not a matter of flipping a switch and walking away. Less is known about the mechanism of action of general anesthetics compared to locals, despite their use for more than years. The most commonly used general anesthetic agents are administered by breathing and are thus termed inhalational or volatile anesthetics.
They are structurally related to ether, the original anesthetic. Their primary site of action is in the central nervous system, where they inhibit nerve transmission by a mechanism distinct from that of local anesthetics.
The general anesthetics cause a reduction in nerve transmission at synapses, the sites at which neurotransmitters are released and exert their initial action in the body. But precisely how inhalational anesthetics inhibit synaptic neurotransmission is not yet fully understood.
It is clear, however, that volatile anesthetics, which are more soluble in lipids than in water, primarily affect the function of ion channel and neurotransmitter receptor proteins in the membranes of nerve cells, which are lipid environments.
Two factors make obtaining a detailed description of how these agents act difficult. The first is that volatile anesthetics, unlike most of the drugs used in medicine, bind only very weakly to their site s of action. As a result, high concentrations, often more than 1, times greater than for typical receptor- or protein-targeting drugs, are needed to achieve an anesthetic state.
This makes it tricky to obtain structural details of anesthetics bound in a specific manner to a protein. Discuss the types of dietary supplements you take with your doctor before your surgery. If you have diabetes, talk with your doctor about any changes to your medications during the fasting period.
Usually you won't take oral diabetes medication the morning of your surgery. If you take insulin, your doctor may recommend a reduced dose. If you have sleep apnea, discuss your condition with your doctor. The anesthesiologist or anesthetist will need to carefully monitor your breathing during and after your surgery.
Before you undergo general anesthesia, your anesthesiologist will talk with you and may ask questions about:. Your anesthesiologist usually delivers the anesthesia medications through an intravenous line in your arm. Sometimes you may be given a gas that you breathe from a mask. Children may prefer to go to sleep with a mask. Once you're asleep, the anesthesiologist may insert a tube into your mouth and down your windpipe. The tube ensures that you get enough oxygen and protects your lungs from blood or other fluids, such as stomach fluids.
You'll be given muscle relaxants before doctors insert the tube to relax the muscles in your windpipe. Your doctor may use other options, such as a laryngeal airway mask, to help manage your breathing during surgery. Someone from the anesthesia care team monitors you continuously while you sleep. He or she will adjust your medications, breathing, temperature, fluids and blood pressure as needed.
Any issues that occur during the surgery are corrected with additional medications, fluids and, sometimes, blood transfusions.
When the surgery is complete, the anesthesiologist reverses the medications to wake you up. You'll slowly wake either in the operating room or the recovery room. You'll probably feel groggy and a little confused when you first wake. You may experience common side effects such as:.
You may also experience other side effects after you awaken from anesthesia, such as pain. Your anesthesia care team will ask you about your pain and other side effects. It's usually used for long operations or those that would otherwise be very painful. It's not clear exactly how it works, but it's known that all anaesthetics stop the nerves from passing signals to the brain.
This means you do not feel anything. Before having an operation, you'll meet a specialist doctor called an anaesthetist to discuss which anaesthetic is most suitable for you.
The anaesthetist will look at your medical history and ask whether anyone in your family has had problems with anaesthesia. They'll also ask about your general health and lifestyle, including whether you:.
The anaesthetist can answer any questions you have. Let them know if you're unsure about any part of the procedure or if you have any concerns. You should be given clear instructions to follow before the operation, including whether you can eat or drink anything in the hours leading up to it. Just before you have surgery, you'll usually be taken to a room where your anaesthetist will give you the general anaesthetic.
The anaesthetic should take effect very quickly. You'll start feeling lightheaded, before becoming unconscious within a minute or so.
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