- WHAT IS IT?
- SPINAL ANAESTHESIA (EPIDURAL OR INTRADURAL)
- PLEXUS ANAESTHESIA
- INTRAVENOUS REGIONAL ANAESTHESIA AND PERIPHERAL BLOCK
It eliminates pain by blocking the nerve fibres that govern sensitivity and body movement. This objective is achieved by the administration of local anaesthetics that temporarily and reversibly interrupt nerve transmission and put the target surgery area "to sleep".
It consists of infiltrating the surgical area with an anaesthetic agent, rendering it insensitive to the pain involved in the operation. Generally speaking, local anaesthesia is only used in minor surgery on small surface areas.
There are different forms of regional anesthesia depending on the area where nerve transmission is to be pharmacologically blocked. Regional anaesthesia can be applied at the beginning of the nerve pathway where they exit the spinal cord (spinal anaesthesia), at plexus level (plexus anesthesia) or to an emerging peripheral nerve (peripheral block).
In spinal anaesthesia (epidural or intradural), the nerve fibres are blocked at their exit point from the spinal cord, and the local anaesthetic agent is given by means of an injection to the spinal column.
Epidural anaesthesia involves administering the anaesthetic agent into a virtual space located outside the spinal canal, where the spinal cord is located.
In intradural anaesthesia, the anaesthetic agent is deposited directly inside the duct.
Although both intradural and epidural anaesthesia may use a catheter for the fractionated administration of local anaesthesia and/or to control postoperative pain (continuous techniques), the intradural catheter only tends to be used in very specific cases.
When they are indicated
In general, these techniques are only used for operations on the lower abdomen, perineum, hip and lumbar spine and/or the lower extremities, particularly intradural anaesthesia.
Advantages and disadvantages
- General anaesthesia, and therefore its side effects, are avoided: nausea, dizziness, disorientation etc...
- The patient remains conscious.
- Possible complications associated with the use of spinal techniques are hypotension (fall in blood pressure) and headache, particularly with intradural anaesthesia.
Plexus anaesthesia consists of giving anaesthesia to areas where the nerve fibres, outside the spine, are clustered together, forming structures called plexuses. Hence, for example, anaesthesia of the brachial plexus, which is responsible for the cutaneous and muscular innervation of the entire upper limb, is used for surgery on the shoulder, arm, forearm or hand. A brachial plexus block can be performed above the collar bone (shoulder surgery) or below it (arm, forearm or hand).
- Axillary anaesthesia is the most commonly used infraclavicular technique in hand surgery. It consists of blocking the nerves in the armpit, where the nerves go round the axillary artery. A fine-calibre needle is inserted above the arterial pulse and is connected to an electrical neurostimulator. When the needle approaches the nerve, the electrical stimulation introduces a certain contractile response in the muscles that depend on this nerve, thus helping us to ascertain proper needle position. At this point, the local anaesthesia is injected through the needle, blocking the nerve in question.
Finally, nerve fibres can be blocked more peripherally, i.e. away from the spine, either selectively (a specific nerve ) or jointly, using the so-called intravenous regional anaesthesia.
It involves the anaesthetisation of the area around the nerve in question, such as blocking the femoral nerve that is responsible for the sensitivity of the anterior surface of the leg.
Intravenous regional anaesthesia
It consists of administering anaesthesia into a hand or foot vein, after placing a tourniquet on the arm or thigh to prevent the passage of the anaesthetic agent into the bloodstream and in order to block the extremity.
When are they indicated?
• With the exception of spinal anaesthesia, all the other locoregional techniques are not applicable in internal organ surgery.
Advantages and disadvantages
• Complications related to the use of these techniques are very uncommon, the most frequent one being the persistence of abnormal sensitivity for several hours after after the operation.
If you wish, any kind of locoregional anaesthesia can be supplemented with sedation, thus allowing you to approach the surgery with greater peace of mind. This sedation should not be confused with general anaesthesia, because unlike the latter, in this case you are not unconscious. Therefore, if you are a very nervous person and/or would rather "sleep right through it", you should go for a general anaesthetic technique, your general condition and type of operation permitting. In this case, your anaesthetist will furnish you with all the information you need.
Nowadays, the risks related to any anesthetic technique are extremely low, so you have absolutely nothing to worry about.
Finally, we hope that this information will help you feel more confident about anaesthesia and will help you to choose, with the help of your anesthesiologist, the most suitable technique in your case.