By specifically blocking certain nerves, a doctor can perform surgery on a patient without putting the patient to ‘sleep’.
No one knows the true origin of peripheral nerve blocks, but the concept was probably born in 1884 when Dr William Stewart Halsted first described the injection of drugs to nerve trunks.
In Malaysia, the practice of ultrasound-guided peripheral nerve blocks landed on our shores in 2006 and has flourished ever since.
Peripheral nerve block is a form of regional anaesthesia used to anaesthetise targeted parts of the body. It can be used as the sole anaesthetic method or in combination with general anaesthesia, administered via a single dose or continuously over a prolonged period of time through a nerve catheter.
Peripheral nerve block is a technique of injecting local anaesthesia around a nerve or group of nerves that control sensation and movement to a specific part of the body. This causes the area to be temporarily numbed and paralysed, allowing for surgical procedures to be carried out.
Peripheral nerve blocks provide excellent anaesthesia and pain relief after surgery, fewer side effects compared to general anaesthesia, and facilitate early physical activity. The use of nerve blocks is associated with reduced use of opioids (pain relief medications) for post-surgical pain. As a result, side effects such as drowsiness, stomach upset and dizziness can often be decreased.
The type of nerve block that is performed depends on the location of the surgery. The anaesthetist will numb specific nerves that are near the area where the surgery is performed.
Examples of peripheral nerve blocks are:
- Blocks of the upper limb
These are peripheral nerve block techniques that provide pain relief for surgery of the upper limb (arm, forearm and hand).
- Blocks of the lower limb
These are peripheral nerve block techniques that provide anaesthesia or pain relief for surgery of the lower limb.
- Various blocks at the trunk
These are peripheral nerve block techniques that provide anaesthesia or pain relief for surgeries of the chest and abdomen.
All peripheral nerve blocks are performed by trained anaesthesiologists. Ultrasound is routinely used to identify the nerve. After it is visualised, a special needle will be used to administer the drug. The nerve block begins to take effect within five to 15 minutes after administration, and should last between 10 and 24 hours, depending on the amount of medication injected.
A catheter (small tubing) can also be placed to provide prolonged nerve block through a continuous infusion of local anaesthetic for longer procedures, as well as for pain relief after surgery that can be extended up to two to three days. The catheter is connected to an infusion pump and is easily removed when no longer necessary.
Certain peripheral nerve blocks need to be done in combination with general anaesthesia, based on the surgical requirements. For others, the patient may remain awake or be given sedation when necessary.
The anaesthetist will always ensure that the patient is comfortable at all times and the effect of the block does not subside before the end of the surgery. After surgery, patients will be reviewed in the wards at regular intervals to monitor recovery and side effects, if any. All patients will be given painkiller pills once they are able to tolerate oral medications.
Complications from peripheral nerve blocks rarely occur. Risks include bleeding, infection, injury to nerves and an adverse reaction to the local anaesthetic medication.
Approximately 1-3% of patients report a tingling sensation in some parts of the area that was numbed for surgery, which may persist over a week. Fortunately, the vast majority of these nerve injuries appear to be temporary rather than permanent, and resolve by themselves over weeks to months.
Many patients have the tendency to choose general (“asleep”) anaesthesia due to the misconception of what regional anaesthesia is and the anxiety related to being awake during needle insertion and surgery.
Information related to the nerve block and surgery will be relayed to a patient prior to surgery for further clarification. Most patients are appropriately sedated, both during the block procedure and the actual surgery. In fact, very few patients have an unpleasant recollection of their anaesthesia experience.
The practice of peripheral nerve block in modern day surgery is growing globally. Peripheral nerve blocks offer multiple benefits of reduced pain severity, reduced side effects, earlier discharge and earlier return to daily activities. Taking all these into consideration, perhaps being awake and painless is not a bad option after all.
>Dr Azrin Mohd Azidin, Dr Amiruddin Nik Mohamed Kamil, Dr Sivasakthi Velayuthapillai and Dr Jamie Tan Wen Yen are from the Department of Anaesthesiology and Intensive Care, Hospital Kuala Lumpur. For more information about anaesthesia in general, the public can attend the “Hari Anestesia 2014” function, which will be held in Auditorium Hospital Kuala Lumpur at 2.45pm on Oct 31.