Epidural anesthesia

Epidural anesthesia

An epidural anesthesia is nothing more than an injection given to block pain in one part of the body: it is essentially not a local anesthesia.

It consists of inserting a needle and then a catheter into the lower part of the spine. The needle is then removed.

The catheter remains inserted fixed to the back, and is used to administer a local anesthetic.

This catheter can be kept in the back for several hours (during labor, for example) or for a few days (after major abdominal surgery).

This type of anesthesia is used to completely block the pain while keeping the patient alert, which would not be possible with general anesthesia.

Epidural anesthesia may be necessary,

• during a birth, including  caesarean sections  (it is the most effective anesthetic technique for keeping pain associated with childbirth under control),
• during some types of surgery,
• after some types of surgery.

But let’s proceed in order, and see where and how it is practiced, what its effects are, and what risks it entails.

Anatomy of the epidural zone

But first, just a few words to better outline the dress of the subject matter.

the subarachnoid space

The subarachnoid space is the space between two of the three membranes that form the meninges:

• between the arachnoid (the middle layer of the three meninges),
• which is located between the dura mater (the most superficial meninx),
• and the pia mater (the innermost of the three meninges in humans).

This space is traversed by numerous fibrous trabeculae, and contains CSF or cerebrospinal fluid.

the epidural space (or extradural space)

It is the area of ​​the vertebral canal between the yellow ligaments (which extend between the lower lamina of one vertebra and the upper lamina of the next vertebra) and the dura mater.

This area contains fatty tissue, small veins and arteries, lymph vessels, and thin bundles of collagen fibers, called meningovertebral ligaments, and the adjacent bone wall.

In the spinal cord, the extradural space (but also called the epidural space) is located between the dura mater and the spinal canal. This contains some loose connective tissue.

The pressure that is present within the epidural space is lower than atmospheric pressure (this information will be useful to us later in the article).

The epidural space is 3-5 mm wide and horizontally unbounded, so epidural anesthesia works wherever it is applied.

Preparation for epidural anesthesia

Epidural (or epidural) anesthesia is the most effective anesthetic technique for controlling pain associated with childbirth. This is usually a safe procedure, but there are some risks of side effects and complications to be aware of.

If you have any questions or concerns regarding epidural (or epidural) anesthesia, discuss them with your doctor before undergoing this anesthesia. Also inform him about any medicines you may be taking.

Your doctor may give you specific advice about what foods, drinks or medicines to take before epidural anesthesia.

Also know that you will not be able to drive for 24 hours after an epidural. For this reason you will have to arrange for someone to take you home.

How anesthesia is done

Epidural anesthesia can be performed at any height in the spine.

• The patient is placed on his side,
• his skin is disinfected,
• and topical anesthetic is applied to the injection site.

Then the Tuohy needle is inserted, a needle with a slightly curved end for inserting the epidural catheter, and then we proceed as we have already explained.

There are two ways, two different techniques, to locate the epidural space.

1. The technique is called the loss of resistance. The needle is attached to a special syringe filled with a saline solution; as the needle is inserted it continuously pushes on the plunger of the syringe until there is a loss of resistance.
2. The hanging drop technique.  In this case, hanging from the outer end of the needle to be inserted is a drop of saline, and when it reaches the epidural space the drop is drawn into the needle (remember that there is lower pressure in the epidural space! ).

Once the epidural space has been found, the catheter is inserted and then the needle is removed.

As long as the epidural catheter is in the back, it can be used for pain relief if needed.

In some cases the catheter may also be connected,

• to an electric pump, to allow the delivery of medicines,
• or to a manual pump that the patient can control directly.

The effects of epidural anesthesia

Carrying out this procedure causes,

• a local anesthesia,
• a blockage of the motor system,
• sympathetic system block.

The preparation of an epidural anesthesia takes about 10 minutes, to which another 10 to 15 minutes must then be added for it to begin to take effect.

The intensity of epidural anesthesia is related to the concentration of the local anesthetic being injected.

Once the anesthetic is stopped, the numbness usually lasts for a few hours before its effects wear off and sensitivity begins to return to normal levels.

The different epidural anesthesias

Epidural anesthesia is generally the responsibility of an anesthesiologist. Depending on the areas and the reasons why it is done, there are different types of epidural anesthesia. You can have it:

• The lumbar epidural,  for operations involving the lower limb (L2-5), inguinal hernias, caesarean section and childbirth.
• The thoracic epidural,  at lower chest level (Th7-12) – laparotomy, cholecystectomy or upper chest levels (Th1-7) for postoperative analgesia of thoracotomy, sternotomy. Performed with catheter only.
• Cervical epidural  at C6-C7 or C7-Th1 spinal levels, carotid endarterectomy, strumectomy, and hand surgery.

Recovery times

After epidural anesthesia wears off, the numbness usually lasts a few more hours before it begins to wear off.

• While the effects of the drugs wear off, you will be advised to rest in a lying or sitting position until feeling returns in your legs.
• This can take a couple of hours, and you may also feel a slight tingling sensation on your skin.
• Tell your doctor or nurse if you experience pain – they can give you medicines to help control it.
• Don’t drive, operate machinery, and don’t drink alcohol for at least 24 hours after an epidural.

Possible risks and complications

Epidural anesthesia is usually a safe procedure, but there is always a small risk of side effects and complications, including:

low blood pressure, which can make you feel dizzy or nauseous

• It is normal for blood pressure to drop somewhat with epidural anesthesia.
• Sometimes this eventuality could also make you feel nauseous.
• Therefore your blood pressure will be monitored constantly.
• If necessary, you will be given fluids and medications through an IV to keep your blood pressure at a normal level.

a temporary loss of bladder control

• After having an epidural anesthesia, you may not be able to tell when your bladder is full, as this anesthesia affects the surrounding nerves.
• A catheter may be inserted into the bladder to allow urine to flow out.
• However, your bladder control will return to normal as soon as the epidural wears off.

an itch in the skin

• Itching can be a side effect of pain medications that can be used in anesthesia.
• In this case, other medications may be given to help ease the itching.

the nausea

• Nausea is less common under epidural anesthesia than with other pain-relieving methods, such as those with morphine and other opioids.
• In these cases, anti-nausea medications can be a remedy for nausea.

headache

• A severe headache may be experienced if the sac of fluid surrounding the spine is accidentally punctured.
• You may therefore need specific treatment for your headache.

of nerve damage

• The needle or epidural tube can damage the nerves, but this is not something that is common.
• However, this can cause a loss of sensation or movement in some areas of the lower body.
• The most common symptom is given a small area of ​​numbness but maintaining normal movement and strength.
• This problem usually improves after a few days to a few weeks, but can sometimes take months.

slow breathing

• Occasionally, some drugs used in epidural anesthesia can cause slow breathing or even drowsiness.
• In this eventuality – which can however be treated easily – you will be monitored closely.

an infection

• An infection can occasionally develop around the skin near the epidural tube. However, it is rare for the infection to spread further.
• If so, antibiotics may be needed.
• It is rarely remedied by emergency surgery.

other very rare complications of an epidural

These can consist of,

• convulsions,
• severe breathing difficulties,
• death,
• permanent nerve damage,

These are rare events, and anesthesiologists undergo extensive training to reduce the chances of these complications.

Statistical data indicate that serious complications following an epidural are rare. The risk of permanent damage from an epidural during labor ranges from 1 in 80,000 cases to 1 in 320,000.

Risks for the child during childbirth

It is believed that the only risks related to the child are related to a possible lengthening of the delivery times.

However, it is not true that the possibility of having an epidural anesthesia increases the risk of having to resort to a caesarean section.