Regional anaesthesia
Encyclopedia
Regional anaesthesia is anaesthesia
affecting only a large part of the body, such as a limb or the lower half of the body. Regional anaesthetic techniques can be divided into central and peripheral techniques. The central techniques include so called neuraxial blocks (epidural
anaesthesia, spinal anaesthesia
). The peripheral techniques can be further divided into plexus blocks such as brachial plexus block
s, and single nerve blocks. Regional anaesthesia may be performed as a single shot or with a continuous catheter through which medication is given over a prolonged period of time, e.g. continuous peripheral nerve block. Regional anaesthesia can be provided by injecting local anaesthetics directly into the veins of an arm (provided the venous flow is impeded by a tourniquet.) This is called intravenous regional techniques (Bier block
).
This differs from Local anaesthesia
, which, in a strict sense, is anaesthesia
of a small part of the body such as a tooth or an area of skin, and Conduction anaesthesia is a comprehensive term which encompasses a great variety of local and regional anaesthetic techniques.
) to allow a surgical operation, or provide post-operative pain relief. Various brachial plexus block
s exist for shoulder
and arm
procedures. Methods similar to routine regional anaesthetic techniques are also often used for treating chronic pain.
In labour and childbirth
, epidural
or combined spinal epidurals provide effective pain relief. Regional anaesthesia is now more common than general anaesthesia for Caesarean section
procedures.
Nerve blocks are widely used in veterinary medicine
to diagnose lameness. A very common application is the diagnosis of navicular disease
in horse
s.
, patients may remain awake during the procedure, resulting in reduced side-effects
and enabling the surgeon to converse with the patient during the procedure if required. However, many patients prefer to receive sedation
either during the block, the procedure, or both.
There is a spectrum of complexity between simple local anaesthetic infiltration and major regional blocks, such as the 'central neuraxial blocks' (spinal and epidural), with nerve blocks lying in the middle. Nerve block
s affecting major peripheral nerves such as the femoral nerve
and sciatic nerve
are also sometimes viewed as regional anaesthetic techniques.
.
Most regional anaesthetic techniques, even in expert hands, have a failure rate of 1–10%. Therefore, general anaesthesia may become necessary even when a procedure was initially planned to be conducted under a regional technique.
For these reasons, regional anaesthesia is only ever conducted in an environment that is fully equipped and staffed to provide safe general anaesthesia should this be needed.
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
affecting only a large part of the body, such as a limb or the lower half of the body. Regional anaesthetic techniques can be divided into central and peripheral techniques. The central techniques include so called neuraxial blocks (epidural
Epidural
The term epidural is often short for epidural analgesia, a form of regional analgesia involving injection of drugs through a catheter placed into the epidural space...
anaesthesia, spinal anaesthesia
Spinal anaesthesia
Spinal anaesthesia , also called spinal analgesia or sub-arachnoid block , is a form of regional anaesthesia involving injection of a local anaesthetic into the subarachnoid space, generally through a fine needle, usually 9 cm long...
). The peripheral techniques can be further divided into plexus blocks such as brachial plexus block
Brachial plexus block
Regional anesthesia of the upper limb by a "brachial plexus block" may be a good alternative to general anesthesia for surgery in this part of the human body. There are numerous...
s, and single nerve blocks. Regional anaesthesia may be performed as a single shot or with a continuous catheter through which medication is given over a prolonged period of time, e.g. continuous peripheral nerve block. Regional anaesthesia can be provided by injecting local anaesthetics directly into the veins of an arm (provided the venous flow is impeded by a tourniquet.) This is called intravenous regional techniques (Bier block
Intravenous regional anesthesia
Intravenous regional anesthesia or Bier block anesthesia is a common anesthetic technique for surgical procedures on the body's extremities where a local anesthetic is injected intravenously. The technique usually involves exsanguination, which forces blood out of the extremity, followed by the...
).
This differs from Local anaesthesia
Local anesthesia
Local anesthesia is any technique to induce the absence of sensation in part of the body, generally for the aim of inducing local analgesia, that is, local insensitivity to pain, although other local senses may be affected as well. It allows patients to undergo surgical and dental procedures with...
, which, in a strict sense, is anaesthesia
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
of a small part of the body such as a tooth or an area of skin, and Conduction anaesthesia is a comprehensive term which encompasses a great variety of local and regional anaesthetic techniques.
Indications and applications
Regional anaesthesia may provide anaesthesia (absence of feeling, including painPain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
) to allow a surgical operation, or provide post-operative pain relief. Various brachial plexus block
Brachial plexus block
Regional anesthesia of the upper limb by a "brachial plexus block" may be a good alternative to general anesthesia for surgery in this part of the human body. There are numerous...
s exist for shoulder
Shoulder
The human shoulder is made up of three bones: the clavicle , the scapula , and the humerus as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints. The major joint of the shoulder is the glenohumeral joint, which...
and arm
Arm
In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...
procedures. Methods similar to routine regional anaesthetic techniques are also often used for treating chronic pain.
In labour and childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
, epidural
Epidural
The term epidural is often short for epidural analgesia, a form of regional analgesia involving injection of drugs through a catheter placed into the epidural space...
or combined spinal epidurals provide effective pain relief. Regional anaesthesia is now more common than general anaesthesia for Caesarean section
Caesarean section
A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...
procedures.
Nerve blocks are widely used in veterinary medicine
Veterinary medicine
Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...
to diagnose lameness. A very common application is the diagnosis of navicular disease
Navicular Disease
Navicular Disease is a soundness problem in horses, more accurately called "navicular syndrome" as opposed to "disease." It most commonly describes an inflammation or degeneration of the navicular bone and its surrounding tissues, usually on the front feet...
in horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s.
Relationship to other anaesthetic techniques
Unlike general anaesthesiaGeneral anaesthesia
General anaesthesia is a state of unconsciousness and loss of protective reflexes resulting from the administration of one or more general anaesthetic agents...
, patients may remain awake during the procedure, resulting in reduced side-effects
Adverse effect (medicine)
In medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as surgery.An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. If it results from an unsuitable or incorrect dosage or...
and enabling the surgeon to converse with the patient during the procedure if required. However, many patients prefer to receive sedation
Sedation
Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...
either during the block, the procedure, or both.
There is a spectrum of complexity between simple local anaesthetic infiltration and major regional blocks, such as the 'central neuraxial blocks' (spinal and epidural), with nerve blocks lying in the middle. Nerve block
Nerve block
Regional nerve blockade, or more commonly nerve block, is a general term used to refer to the injection of local anesthetic onto or near nerves for temporary control of pain. It can also be used as a diagnostic tool to identify specific nerves as pain generators...
s affecting major peripheral nerves such as the femoral nerve
Femoral nerve
The femoral nerve, the largest branch of the lumbar plexus, arises from the dorsal divisions of the ventral rami of the second, third, and fourth lumbar nerves...
and sciatic nerve
Sciatic nerve
The sciatic nerve is a large nerve fiber in humans and other animals. It begins in the lower back and runs through the buttock and down the lower limb...
are also sometimes viewed as regional anaesthetic techniques.
Complications
Unlike a minor local anaesthetic infiltration to allow a wound to be sutured, or a skin lesion to be excised, regional anaesthesia may involve large doses of local anaesthetic, or administration of the local anaesthetic very close to, or directly into the central nervous system. Therefore there is a risk of complications from local anaesthetic toxicity (such as seizures and cardiac arrest) and for a syndrome similar to spinal shockSpinal shock
Spinal shock was first defined by Whytt in 1750 as a loss of sensation accompanied by motor paralysis with initial loss but gradual recovery of reflexes, following a spinal cord injury – most often a complete transection. Reflexes in the spinal cord caudal to the SCI are depressed or absent ,...
.
Most regional anaesthetic techniques, even in expert hands, have a failure rate of 1–10%. Therefore, general anaesthesia may become necessary even when a procedure was initially planned to be conducted under a regional technique.
For these reasons, regional anaesthesia is only ever conducted in an environment that is fully equipped and staffed to provide safe general anaesthesia should this be needed.