Los nervios, como mínimo están compuestos por dos fibras diferentes: un tipo (sensoriales) que transmiten al cerebro la temperatura, el tacto y el dolor, y otro tipo (motoras) que las emplea el cerebro para enviar órdenes a los respectivos músculos que inervan. De hecho, si usted coloca su dedo en una superficie caliente, los nervios comunicarán al cerebro (sensación) “esto quema” y el cerebro comunicará al dedo (actividad motora) “muévete” para quitarlo.
La inyección de fármacos específicos (anestésicos locales) cerca de los nervios, adormece areas del cuerpo específicas (el brazo o la pierna o el tórax o el abdomen) y permite que se puedan realizar procedimientos sin que usted este inconsciente (anestesia general). Esto significa que el objetivo de la anestesia regional es detener (o bloquear) temporalmente la conexión entre el cerebro y una parte específica del cuerpo. Las ventajas que presenta la anestesia regional con numerosas:
Regional anaesthesia represents an anaesthetic technique that involves injecting drugs close to the nerves or to the spinal cord to provide surgical anaesthesia or pain relief after surgery. Regional anaesthesia commonly refers to either peripheral nerve blocks (fig 1), epidural and/or spinal anaesthesia, known as neuraxial blocks (fig 2). The drugs used are called local anaesthetics and their main purpose is to numb the nerves for a certain duration of time, after which the nerve function returns to normal. The result of regional anaesthesia is numbness over large parts of your body, such as from waist down, an entire limb or only part of it.
Regional anaesthesia is very safe and avoids potential complications and side effects common to sedation and general anaesthesia.
A very popular regional anaesthesia technique used for pain control during labor and delivery is the epidural block. This way the mother can be pain free and awake to push the baby.
It’s important that the epidural block is provided and monitored by an anaesthesiology doctor.
A peripheral nerve block is a subtype of regional anaesthesia where local anaesthetics are injected close to peripheral nerves. A peripheral nerve is a branch of the spinal cord, which transmits electrical signals to various areas of the body: limbs, internal organs etc. In the case of the hand for example these electrical signals are involved in commanding our fingers to move or to bring sensations like pain from an injured finger to our brain. The local anaesthetic drugs temporarily numb the nerve and therefore, you will not feel the pain from the injured finger and will not be able to move it.
If used in conjunction with general anaesthesia, a nerve block provides pain relief after surgery. If there is no general anaesthesia involved or only sedation is being used, the nerve block will provide numbness to allow the surgery to happen without any pain feeling.
Most of the time a peripheral nerve block is performed by a once off injection with a numbing effect lasting up to 12-24 hours, depending on the drugs being used. In certain cases, the doctor may decide to put a small plastic tube (nerve catheter) close to the nerve to deliver a continuous infusion of local anaesthetic. In this case, the numbing effect can last as long as the infusion is running (usual maximum 3 to 5 days).
Fasting is important to prevent stomach content going into the lungs when you lose conscience that occurs after general anaesthesia or sedation. In those rare cases when the regional anaesthesia is not working completely you may require a general anaesthesia or sedation to be given. If this is the case, as your turn unconscious, you can regurgitate or vomit and not be able to avoid the stomach content to go to your lungs.
Therefore, fasting is mandatory before regional anaesthesia.
The advantages of regional anaesthesia are:
Insufficient or failed block
In some occasions, the block might not work or you might still feel some pain during the operation. If that happens, your anaesthetist will help you: giving you more regional anaesthesia, adding sedation or general anaesthesia.
Nerve injury
How common is it? A nerve injury after a peripheral nerve block is an uncommon event. In the first few days after surgery up to 15% of patients may experience some abnormal feeling. This rarely results in permanent injury and it get better with time: only 0–2.2% at 3 months, 0–0.8% at 6 months, and 0–0.2% at 1 year still have any symptoms.
It is extremely rare that the nerve never recovers, leading to severe pain or permanent numbness or paralysis in the area previously numb and this can happen in 0.014% to 0.04% of patients.
In comparison, nerve injuries can occur after general anaesthesia too. This happens due to nerve compression during surgery for example. In this instance, the incidence of injuries lasting few days is 1:100 (1%), of those lasting > 3months is 1:2000 (0,05%), and of that lasting > 1 year is 1:5000 (0,02%).
How do I know a nerve injury has occurred? When to call for help? As the nerve becomes numb after the local anaesthetic injection, it is no possible to diagnose the nerve injury immediately after the injection. If you experience any of the following: abnormal sensation (pins and needles, strange sensation or pain) in the region that was numb before, persistent numbness or muscle weakness lasting beyond the expected time for block to wear off (usually 48 hours if there is no catheter in place), this could signal the occurrence of nerve injury. In this case, please contact the anaesthesia department of the hospital where the block was performed urgently. The recovery of the nerve function depends on the cause of injury and the length of time until recognition of injury.
Why did it happen? There are few reasons why a nerve injury can happen after regional anaesthesia:
Infection
Infection after peripheral nerve block is rare. When it happens usually is superficial and manageable, with no permanent consequences. In exceptional cases it could be in the proximity of the nerve and lead to nerve injury as described above. To decrease the risk of infection, peripheral nerve blocks are done using an aseptic technique with thorough skin cleaning. If you notice any swelling, redness, warm feeling or pain at the site of injection please contact the anaesthesia department of the hospital where the block was performed urgently.
Bleeding
Bleeding is rare and can occur at the time of injection or later. Usually is managed by applying local pressure. If you notice any swelling, bruising or pain at the site of injection please contact the anaesthesia department of the hospital where the block was performed urgently. Due to the risk of bleeding, patients taking anticoagulant drugs may have restrictions to have regional anaesthesia. If you are one of those patients, please inform your attending anaesthesiologist about the medication you are taking.
Allergic reaction
Regional anaesthesia uses far less drugs than general anaesthesia: one or two local anaesthetic drugs are used to numb the nerve. If sedation is used with a peripheral nerve block, another drug can be added. The incidence of the severe allergic reaction (anaphylaxis) with anaesthesia is approx. 1:10 000. Although any of the drugs used during a peripheral nerve block could trigger anaphylaxis, the local anaesthetics are the ones to blame in most of the times. The incidence of an allergic reaction to local anaesthetics (approx. 1:10 000 to 1:20 000 cases), is far less common than with general anaesthesia.
Local anaesthetic systemic toxicity
The maximum incidence of local anesthetic systemic toxicity is approx. 1:1 000. It happens when the local anaesthetic drug enters the bloodstream and causes toxicity. This can occur due to accidental unrecognized intravascular injection at the time when the block is performed or due to slow absorption afterwards. It can present with light-headedness, dizziness, drowsiness, tingling around the mouth and fingers, metallic taste in your mouth, ringing in your ears, blurred vision, confusion, agitation, coma, seizures and heart disturbance. Specific treatment needs to be started promptly. The use of ultrasound machine and certain safety steps during the injection may prevent this from happening.
Block specific complications
Some blocks, particularly those around neck have specific complications like:
Click here for a valuable resource from the Royal College of Anaesthetists UK. This includes a number of patient leaflets and videos explaining more about the anaesthesia for various types of surgeries, the associated risks and Patient FAQs.
Some of the most common barriers to regional anaesthesia are listed below. It is very important that you tell your anaesthetist all about your medical history and medication.
Common strong barriers:
Common weak barriers:
– if you take blood-thinning drugs, such as warfarin, rivaroxaban, apixaban, dabigatran, or other similar drugs.
– if you take antiplatelet drugs like aspirin, clopidogrel, prasugrel, ticagrelor, or other similar drugs.
common while the severe allergic reaction (anaphylaxis) is rare in anaesthesia, approx. incidence is 1:10 000.
No history of drug induced allergic reaction cannot guarantee that you will not experience an allergic reaction during the operation. However, true allergic reaction to local anaesthetics is rare. The incidence of anaphylaxis to local anaesthetics is approx. 1:10 000 to 1:20 000, which is less than the incidence of anaphylaxis with general anaesthesia (1:10 000).
More commonly, you could experience some mild local reaction at the injection site called contact dermatitis (redness, blisters, skin peeling off) up to 72 hours after injection.
If you had a previous allergic reaction to any food, drug, local anaesthetic, or material you should share this information with your attending anaesthetist. Your anaesthetist will evaluate the nature of your previous reaction and may order further tests to clarify it.
Yes. Recreational drugs should be avoided before any type of anaesthesia. They affect with your capability to consent for surgery / anaesthesia and can interfere with the drugs being given normally during an anaesthetic. Also, stopping suddenly some recreational drugs could lead to severe withdrawal symptoms which can be life threatening. Please mention the use of any recreational drugs to your anaesthetist before any anaesthetic.
Depending on the type of surgery you may go for, your anaesthetist may recommend you a specific type of block. Deciding if you would like to have the block or not is your decision ONLY. The anaesthetist will help you in making this decision by explaining why the block is indicated, what are the benefits and the risks of it. Also, he/she will explain what the alternatives and the potential risks associated. Once you have thoroughly analysed all these you can consent or not to having the block.
You can always refuse to have a block. If the block is indicated for surgical anaesthesia, the alternative is to have general anaesthesia for your surgery. Depending on your medical background this may carry more or less risks than a block. If the block is done mainly to provide pain relief after general anaesthesia the alternative is to receive higher doses of strong painkiller drugs (opioids, for example). These may have unpleasant side effects like nausea, vomiting, itching, confusion, sedation, respiratory depression, constipation, inadequate pain relief or anaphylaxis. Your anaesthetist will discuss with you all the pros and cons of each alternative and will assist you in making a decision that you are happy with.
General anaesthesia and regional anaesthesia have different risk profiles. For example, with regional anaesthesia you could suffer a nerve injury, an allergic reaction (smaller chance than with general anaesthesia) or local anaesthetic toxicity while general anaesthesia could lead to life threatening heart and lung complications, teeth and mouth injuries, nausea, confusion, and a feeling of unwell afterwards. Overall, for some surgeries and patients, regional anaesthesia is regarded as a technique with less severe risks than general anaesthesia.
Your medical history is the key element to help determine the right and safest type of anaesthetic for your, be that regional or general anaesthesia or a combination thereof.
Yes. You can always have a combination of general and regional anaesthesia. Some surgeries like the ones in your abdomen or chest may not be done with regional anaesthesia alone and may require general anaesthesia. In this case a block could be done before or after the surgery to relief some of the pain. For example, an epidural may be placed to help you with the pain after an abdominal surgery (for example, removing your large bowel during cancer surgery).
At times, due to multiple causes, the block may not work as expected for several reasons. Your anaesthetist will be by your side all the time and provide help if you need.
Before surgery starts, the block will be tested gently. If you feel any discomfort at this time, depending on the circumstances, the block may be repeated, or sedation or general anaesthesia may be offered. Very rarely, you may feel some discomfort late after surgery has started or while it may be close to finish – in this instance general anaesthesia, sedation or intravenous pain killers may be offered depending on circumstances. If the block is not giving you enough pain relief after surgery some options can be used to improve its function: different drugs could be given if you have a catheter (epidural or peripheral nerve catheter), the block could be repeated, or regular/ morphine-like pain killers can be added.
It is important to communicate with the healthcare staff around you at any point you are concerned about what you are experiencing.
When both you and the anaesthetist are happy that the block has taken effect, surgery will begin. After a successful block and if no general anaesthesia is being used, you should not feel pain at all during surgery although some reduced movement may be present. You may feel touch, pressure and pulling during surgery and this is all normal. Some people, particularly when anxious about the surgery, may confound these sensations with pain but it is not the case. To make this experience more comfortable, sedation may be used. It is important to communicate with the healthcare staff around you at any point you are concerned about what you are experiencing.
The injection will be done by a trained doctor, anaesthetist, experienced in the regional anaesthesia with the help of a nurse. In teaching hospitals, this may be given by a doctor in training (resident) under the supervision of a senior anaesthetist.
In general, the injection is not more uncomfortable than a regular injection you may have experienced before. Normally, some quick acting local anaesthetic is given to the skin with a thin needle to make the block injection more comfortable. If the injection is given in a sensitive area like your neck for example you may receive some sedative drug to relieve anxiety. As the injection is made you may feel pins and needles or a sharp tingle in your arm or leg. If the discomfort during the block is too much for you or if you experience sharp, electrical shock like pain shooting down the nerve into your leg or arm please try to remain still and inform your anaesthetist.
Sometimes a nerve stimulator (a small electrical equipment) is used in addition to the ultrasound. You will feel muscle twitches on the territory dependent of the nerve stimulated. Usually this is not painful.
Your anaesthetist or a member of the anaesthesia team will be always present during the operation, to ensure your safety and comfort.
If you are having regional anaesthesia only, you will remain alert and aware of your surroundings and of what happens during the operation. A screen/drape will stop you from seeing the actual surgery.
If no sedation or general anaesthesia is used, you will be able to talk to the anaesthesia team during the operation whenever you wish. It is important to communicate with the healthcare staff around you at any point you are concerned about what you are experiencing during surgery.
If you do not wish to be aware, sedation can be used to make you more comfortable.
Depending on the drugs used for the block, it is expected to have a return of normal sensation and movement after a specified time frame. The anaesthetist will inform you when to expect the block to wear off and return of normal function. When the block wears off you may feel tingling sensation, pins and needles, strange sensation, and some pain – this is the normal block resolution process. In the first few days after a block up to 15% of patients may experience some remaining abnormal sensation. Although permanent injury is extremely rare, please inform the anaesthesia staff as soon as possible if these symptoms persist beyond the expected time.
An epidural is a subtype of regional anaesthesia where a flexible plastic tube (catheter) is placed very close to the spinal cord. The catheter serves the purpose of delivering local anaesthetics to numb the spinal nerves. It is routinely used for pain relief after big abdominal or chest surgeries in conjunction to general anaesthesia. In some cases, it can be used to provide anaesthesia for surgery alone – for baby delivery through a Cesarean section. The catheter is connected to a pump with local anaesthetic and can be used continuously up to 5 days after surgery.
Benefits:
Spinal anaesthesia is a subtype of regional anaesthesia where a single shot injection is given in your back, in the fluid sac covering the spinal cord (fig 3). It is routinely used on its own for providing anaesthesia for lower abdominal and lower limbs surgery. The effect of it can last from 40 minutes to 3-4 hours depending on the drugs given. It can be used with sedation to increase patient comfort.
Epidural and spinal anaesthesia are safe procedures used routinely in clinical practice, but like any other medical procedure they carry risks and have been associated with complications. Although some side effects and potential complications are more common than others, the life-threatening ones or those which could lead to paralysis or life threatning outcomes are very rare.
Risks and complications:
Common:
Rare and very rare:
The process of assessment and performance of epidural and spinal anaesthesia is designed in such a way to increase the safety of the procedure. Paralysis/paraplegia can result from direct needle injury to the spinal cord or from a later complication like bleeding or infection around the spinal cord. Paralysis or death after these procedures are exceptional events with a general frequency of approx. 1:54 500 to 1:141 500. The frequency of paraplegia/paralysis in pregnant patients after an epidural or spinal anaesthesia is approx. 1:250 000.
Most patients can safely have an epidural or spinal anaesthesia. It is important to fully disclose to the anaesthetist your medical history and current medication.
You may not be suitable for an epidural or spinal anaesthetic if:
There are many causes of headache unrelated to the epidural or spinal anaesthesia that can occur after an operation.
A common cause of headache after an epidural anaesthesia is called post-dural puncture headache. The frequency of this is approx. 1:100 after an epidural and of approx. 1: 500 after spinal anaesthesia. Their risk is a greater for young people and pregnant or in labour.
Whit an epidural this happens after an accidental puncture of the bag of fluid around the spinal cord which leads to leaking of fluid out of the sac. With spinal anaesthesia this puncture is done intentionally to deliver the local anaesthetic. Although is done with a very thin needle (to decrease the risk of this from happening) the fluid leak may still happen.
The characteristics of this type of headache are:
If you notice this happens you should contact your surgical team, anaesthetist or primary care physician. If you do not have a physician’s contact, you should be evaluated in an emergency room. If you are still in the hospital, you should notify the healthcare providers caring for you.
To relief this symptom you should lie flat, take a simple pain relief drug, such as paracetamol and ibuprofen or another anti-inflammatory drug as well (providing you are not intolerant or allergic to it). You should also keep hydrated and take caffeine drinks (such as tea, coffee or cola). You should avoid straining and heavy lifting. If it does not settle after 48 hours with the above treatment a specific procedure (blood patch or other) may be required.
Suffering back pain after an epidural or spinal anaesthesia is not more common than suffering back pain after undergoing general anaesthesia. Even if you experience back pain after surgery, it’s most probably due to immobilization and position during the operation rather due to the epidural or spinal anaesthesia. In this context, the back pain is usually mild, rarely radiates to lower extremities and lasts up to 48 hours. The pain resolves by itself without extra medication, but if requested, oral pain killers (e.g. paracetamol or NSAIDs) can provide a good pain relief.
Having lumbar disc disease does not prohibits a patient from having an epidural or spinal anaesthesia. The area where the epidural or spinal needle aims to reach is not the area where the diseased lumbar disc lays. Due to back pain, positioning you for the epidural or spinal anaesthesia could be more challenging and this could make the procedure itself more defiant for the anaesthetist. If you had previous spine surgery, the epidural or spinal anaesthesia placement can be more difficult and take longer to do. Also, previous back surgery could make the epidural work less efficiently. Some types of previous back surgery could make you unsuitable for an epidural or spinal anaesthesia.
Placing a urinary catheter is not mandatory if you have neuraxial anaesthesia (epidural or spinal). One of the potential complications of epidural and spinal anaesthesia is that temporarily you may not be able to void your bladder spontaneously. If the medical team feels you have a very high risk of this happening, they may decide to insert a urinary catheter to help you with emptying the bladder. Sometimes, particularly for big surgeries, a urinary catheter may be useful to evaluate your kidney function during and after surgery rather than having an epidural, for example. Also, some operations (like urological interventions) may require you to have a urinary catheter. Your medical team will remove it as soon as is no longer required.
Breastfeeding is essential after delivery and has numerous advantages for both baby and mother. Your medical team, including the anaesthetist, provides the utmost care for you and your baby’s wellbeing.
In general, most drugs given to you during labour will pass into the milk and because of the effect they may have on the baby some drugs are avoided during labour. The amount of the drug found in the milk depends on various factors like the route of administration, amount of dose and specific characteristics of the drug, how easily it dissolves and enters the blood stream, etc.
Normally, the drugs used for regional anaesthesia during labour are known to be safe for both the mother and the baby. Even though they pass into the milk, it is in a very small amount that was shown to have no side effects. Epidural labour analgesia has proven to be safe for babies and represent a routine practice in many centres. This type of pain relief will avoid the use of morphine-like drugs which can make the baby sleepy after delivery.
Sedation is the process of reducing your irritability, fear, agitation, anxiety and recall with the purpose of achieving a relaxed state that facilitates certain medical procedures. It is a complex state achieved by using specific drugs called sedatives given intravenously. Depending on the drug and dose given the effect of sedation can range from being awake and relaxed to being fully asleep but rousable to physical stimulation.
In regional anaesthesia, sedation is used to facilitate the performance of a block or to decrease your awareness to the surgical theatre environment. In this case we practice ‘’conscious sedation’’ which means that you will be calm and relaxed and my feel sleepy, but you are easily responding to verbal commands.
If you are given light sedation, then you may feel relaxed and comfortable. If deep sedation is used, you may be asleep. The way you feel during sedation depends on the type of drug and dose given and you may find yourself anywhere between the two states mentioned above. People who had sedation described it by using various words: awake and relaxed, calm, sleepy, spaced out and dreamy, relaxed and happy, did not realized time passed, detached from the event around me. Overall, it is a pleasant state making your operation more comfortable.
Sedation is a procedure done by a trained doctor, usually an anaesthetist. It is a safe procedure, used routinely for facilitating various medical and surgical interventions.
Some of the common risks of sedation are:
If you wish sedation or not is totally your choice. The operation room is a very different environment compared to other parts of the hospital. You might feel uncomfortable and anxious before undergoing an operation. In this instance the use of sedation will alleviate your fear and anxiety and could make the entire surgical experience more enjoyable.
For most of the blocks, a small dose of a sedating drug is being used routinely to take your anxiety away and make the block procedure more pleasant. This will not put you to sleep. You will still be awake but just more relaxed than before. If you wish to be awake, no extra sedation drugs will be given.
During the operation, if you wish not to be aware of what is happening around you, a deeper level of sedation may be achieved by giving more of the sedating drug and you will be apparently asleep, unaware, but very easily rousable to verbal commands or physical contact.
Either if you choose to be awake or under sedation, a member of anaesthesia team will be with you all the time during surgery.
Sedation may still affect you after the operation. Although you are awake, your memory, attention, perception, and awareness may be affected. How long it takes to fully get rid of all these residual effects depend on each individual and also on the drugs used. It is usually recommended not to do any of the following for at least 24 hours after surgery:
If you still not feel fully back to baseline after 24 hours, please be patient and give yourself some more time. Best way of recovering after sedation is with good sleep and hydration.
You should have a friend or responsible adult caring for you at home overnight after receiving sedation. They should have the contact number of the hospital and your family’s in case of emergencies.
The duration of the block you had depends on the type of block given, the drugs and the doses used. The doctor giving you the block will inform you about the expected pain relief time frame.
The effect of a spinal anaesthetic can last anywhere between 40 minutes to 3-4 hours. During this time, you may not move your legs or feel pain until the block starts to wear off.
An epidural block lasts as long as the infusion through the catheter in your back is given, usually maximum 5 days. The epidural provides only pain relief, so normally you can move your legs (even get out of bed in some situations), and even feel some mild discomfort at the surgical site.
A peripheral nerve block usually resolves after 24 hours. Rarely, long-acting drugs may be used and the effect may outlast 24 hours. Your doctor will inform you about this.
When the block resolves the feeling and movement comes back gradually. During this you may experience some tingling, pins and needles, pain related to the surgery and not being able to move your limb normally.
When the anaesthesia block wears off, your sensation and movement slowly return, sometimes with a tingling sensation, pins and needles, abnormal sensation and movement. It is normal to start experiencing some pain, ache or soreness from the surgical site as the block wears off.
To ensure the pain is not too severe when the block wears off it is important to take your prescribed pain relief drugs regularly while the limb is still numb or as soon as you feel any discomfort. This will facilitate a smooth transition when the block is wearing off.
Ask for help or clarifications any time something is not clear to you or are concerned about your post-operative progress. You should contact the surgical or anaesthetic team who performed the procedure. Alternatively, the emergency department of the hospital where the procedure took place or your local emergency department can be contacted.
Some of the situations that should be brought urgently to the attention of the medical team are:
You should contact the anaesthetic department who performed the procedure. Even out of business hours there are anaesthetists on call that could take you phone call and answer to your concerns. Alternatively, the surgical team, the emergency department of the hospital where the procedure took place, or your local emergency department can be contacted.
If you have received sedation for your block, please read Question 5 regarding post sedation care.
While the block is still effective (your sensation and movement are not back to normal) please do the following:
Return to work depends on the type of surgery and the required rehabilitation after that surgery. Your surgical team will gladly answer to this question.
You cannot drive safely if your arm or leg is still affected by the block. Also, even after the block resolves, the limb may still be in a sling or cast, or you may have to use crutches or you may experience pain. All these plus the fact your limb is not fully recovered after surgery make driving unsafe. As the rehabilitation period depends on the type of surgery, your surgical team will advise you how long you should not drive.
Also, if you have received sedation, it is not advised to drive at least 24 hours after.
In some jurisdictions, driving under the effect of medication like sedation or when unfit after surgery, voids your insurance in case of an accident and can lead to prosecution.
One of the advantages of regional anaesthesia is that it helps discharging patients quicker from the hospital. Also, it is widely used for day case surgery.
You could go home after receiving regional anaesthesia if the surgery you had does not require you to stay in hospital.
It is advisable to have a responsible adult watching you or those in your care until you are recovered enough. It is not recommended to be alone at home after surgery. After surgery, pain and lack of function in your limbs for example could prevent you from taking care of yourself.
If you have received sedation you should have a responsible adult caring for you at least 24 hours. Please see Question 5 about sedation for further details.
Depending on how the anaesthetic department operates you may have some follow up arranged. Please enquire about this before going home.
If you go home after your operation, you may receive a follow up phone call from the anaesthesia team to enquire how you are recovering after the block.
If you are kept in hospital, the anaesthesia department may visit you in the days after surgery.
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