Types of Anaesthesia

LOCAL ANAESTHESIA AND

REGIONAL ANAESTHESIA

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Types of Anaesthesia

Local anaesthesia – the administration of an anaesthetic agent to one part of the body by local infiltration or topical application. It is usually administered by the surgeon.

Used for minor proceduresif the patient’s cooperation and the condition warrants

its use.

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Types of Anaesthesia cont…

Regional Anaesthesia – is broadly defined as a reversible loss of sensation in a specific area or region of the body when a local anaesthetic is injected to purposefully block or anaesthetize nerve fibres in and around the operative site.

Commonly R.A techniques include:Spinals (subarachnoid block), epidurals (extradural space) , caudals, and major peripheral nerve blocks.

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Types of Anaesthesia Care Monitored anaesthesia care (MAC) is scheduled when an

anaesthesia provider’s presence is necessary.

- The infiltration of the surgical site with a local anaesthesia and supplements the local anaesthesia with IV drugs that provide sedation and systemic analgesia. Additional medication may be used to optimize the patient’s physiologic status.

- Can be used for some procedures for critically ill patients who may poorly tolerate a general anaesthetic without extensive invasive monitoring and pharmacologic support.

- Often used for healthy patients undergoing relatively minor surgical procedures.

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Types of Anaesthesia Care cont….

Conscious sedation/analgesia is administered for specific short-term surgical, diagnostic, and therapeutic procedures within the hospital and ambulatory centre.

It allows patients to tolerate unpleasant procedures while maintaining adequate cardio-respiratory function and the ability to respond purposefully to verbal command and/or tactile stimulation

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Conduction Anaesthesia

Conduction anesthesia is a comprehensive term which encompasses a great variety of local and regional anesthetic techniques.

Conduction anesthesia allows patients to undergo many surgical procedures without significant pain or distress. In many situations, such as cesarean section, conduction anesthesia is safer and therefore superior to general anesthesia. In other situations, either conduction or general anesthesia are suitable. Anaesthetists sometimes combine both techniques.

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Conduction Anaesthesia cont…

Conduction anesthesia is also used for relief of non-surgical pain, also to enable diagnosis of the cause of some chronic pain conditions.

The most common form of conduction anaesthesia is probably local anaesthesia to enable dental procedures.

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Clinical techniques include:

Surface anesthesia - application of local anesthetic spray, solution or cream to the skin or a mucous membrane. The effect is short lasting and is limited to the area of contact.

Infiltration anesthesia - injection of local anesthetic into the tissue to be anesthetized. Surface and infiltration anesthesia are collectively topical anesthesia.

Field block - subcutaneous injection of a local anesthetic in an area bordering on the field to be anesthetized.

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Local Anaesthesia

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Local Anesthesia

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Clinical techniques include:cont…

Peripheral nerve blocks - injection of local anesthetic in the vicinity of a peripheral nerve to anesthetize that nerve's area of innervation.

Plexus anesthesia - injection of local anesthetic in the vicinity of a nerve plexus, often inside a tissue compartment that limits the diffusion of the drug away from the intended site of action. The anesthetic effect extends to the innervation areas of several or all nerves stemming from the plexus.

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Peripheral nerve blocks

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Clinical techniques include:cont…

Epidural anesthesia - a local anesthetic is injected into the epidural space where it acts primarily on the spinal nerve roots. Depending on the site of injection and the volume injected, the anesthetized area varies from limited areas of the abdomen or chest to large regions of the body.

Spinal anesthesia - a local anesthetic is injected into the cerebrospinal fluid, usually at the lumbar spine (in the lower back), where it acts on spinal nerve roots and part of the spinal cord. The resulting anesthesia usually extends from the legs to the abdomen or chest.

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Lumbar Vertebrae

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Spinal Block - Position

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Spinal and Epidural Anaesthesia

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Spinal and Epidural Anaesthesia

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Clinical techniques include:cont…

Intravenous regional anesthesia (Bier's block) - blood circulation of a limb is interrupted using a tourniquet (a device similar to a blood pressure cuff), then a large volume of local anesthetic is injected into a peripheral vein. The drug fills the limb's venous system and diffuses into tissues where peripheral nerves and nerve endings are anesthetized. The anesthetic effect is limited to the area that is excluded from blood circulation and resolves quickly once circulation is restored.

Local anesthesia of body cavities (e.g. intrapleural anesthesia, intraarticular anesthesia).

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Intravenous Regional Anaesthesia

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Caudal Block

Anatomy of the Caudal Space

Caudal analgesia is produced by injection of local anaesthetic into the caudal canal. This produces block of the sacral and lumbar nerve roots. It is useful as a supplement to general anaesthesia and for provision of postoperative analgesia. This technique is popular in paediatric patients. Catheter insertion may be performed for continuous caudal block.

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Caudal

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Local Anaesthetics Local anaesthetic agents can be defined as drugs which

are used clinically to produce reversible loss of sensation in a circumscribed area of the body.

Drugs include Beta-adrenoceptor antagonists, opioid analgesics, anticonvulsants and antihistamines.

Local anaesthetics can be divided into two groups on the basis of their chemical structure:

- amides: Lignocaine, prilocaine and bupivacaine

- esters: Amethocaine, benzocaine, cocaine

e.g., amethocaine lozenges for the oropharynx, cocaine for nasal surgery.

Most blocks take 5 – 20 minutes to work.

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The potential side effects and/or complications

The most common side effects of a block is a temporary weakness or paralysis of the affected area.

The complications may arise when the L.A is injected in the wrong place, e.g., 10-20mls of L.A is injected into a vein by mistake, it may cause convulsions and even cardiac arrest.

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Why choose a L.A or R.A?

L.A avoids some of the risks and unpleasantness, such as nausea and vomiting, which sometimes occurs with G.A.

L.A often lasts longer than the surgery, providing pain relief for several hours after operation.

L.A may reduce blood loss.

Some patients feel more “in control” when they are awake during surgery.

THE END