11/14/24, 10\:46 AM Regional Anaesthesia
Regional Anaesthesia
Table of contents
Key points ⚡
Succinct notes to superpower your revision
Regional anaesthesia (RA)\: local anaesthetic blockade of peripheral nerves and central neuraxis, used for perioperative
and postoperative analgesia, allowing patients to remain conscious during surgery and providing prolonged pain control.
Advantages\: avoids adverse e
reduces surgical stress response, blood loss, postoperative pneumonia, and venous thromboembolism.
Monitoring\: ECG, blood pressure, SpO ; begin before procedure, continue for at least 30 minutes after completion.
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Types\:
Central neuraxial blocks (CNB)\: spinal, epidural, caudal anaesthesia
Peripheral nerve blocks (PNB)\: local anaesthetic near peripheral nerves
Intravenous regional anaesthesia (IVRA)\: local anaesthetic intravenously into exsanguinated limb
Topical and in
Spinal anaesthesia\: thin needle into subarachnoid space, rapid onset of dense anaesthesia, preferably performed below
spinal cord termination; used for lower abdominal, pelvic, and lower extremity surgery; duration\: 2-3 hours.
Epidural anaesthesia\: larger needle into epidural space, catheter for prolonged anaesthesia, useful for upper abdominal
and thoracic surgery; vasopressors (metraminol, ephedrine, phenylephrine) manage hypotension.
Caudal anaesthesia\: extension of epidural space, more useful in paediatric patients.
Central neuraxial block complications\: technique failure, nerve trauma, haemodynamic instability, post-dural puncture
headache, meningitis, epidural haematoma/abscess, back pain, urinary retention.
Peripheral nerve blocks\: site-speci
alone, with general anaesthesia, or for postoperative analgesia.
Upper extremity blocks\: interscalene (shoulder), supraclavicular, infraclavicular, axillary (elbow, forearm, hand).
Trunk blocks\: erector spinae, pectoral nerve, serratus anterior (chest wall); transversus abdominis plane, rectus sheath,
ilioinguinal/iliohypogastric (abdominal); intercostal (rib fractures, thoracic surgery).
Lower extremity blocks\: femoral, fascia iliaca, obturator, sciatic, popliteal, saphenous nerve blocks.
Peripheral nerve block complications\: technique failure, nerve trauma, local anaesthetic systemic toxicity, infection,
pneumothorax, phrenic/recurrent laryngeal nerve palsy (supraclavicular), vascular injury (femoral).
Local anaesthetics\: block sodium channels, vary in potency, duration, stability, toxicity; common drugs\: lidocaine,
bupivacaine, ropivacaine, levobupivacaine, prilocaine; adrenaline may be added to prolong action.
Contraindications\:
Absolute\: patient refusal, localised infection, allergy
Relative\: abnormal anatomy, coagulation disorders, antiplatelets/anticoagulants, neurological disease, haemodynamic
instability
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Introduction
Regional anaesthesia (RA) is a subspecialty in anaesthetics focusing on the local anaesthetic blockade of peripheral
nerves and central neuraxis. Regional anaesthesia is widely used for perioperative and postoperative analgesia in
modern anaesthetic practice and is a core skill set in anaesthetic training.
Regional techniques allow the patient to remain conscious during surgery and provide prolonged postoperative pain
control.
Other advantages of regional anaesthesia include\:
Avoidance of adverse e
Improved postoperative pain relief
Decreased or no opioid use
Faster recovery
Reduces stress response to surgery
Reduced blood loss
Decreased incidence of postoperative pneumonia and venous thromboembolism
The minimum monitoring required during regional anaesthesia includes ECG, blood pressure and SpO 2,
begin before the procedure and continue for at least 30 minutes after the completion of the procedure.
1
which should
Types of regional anaesthesia include\:
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1. Central neuraxial blocks (CNB)\: placement of local anaesthetics around the nerves of the central nervous system and
include spinal anaesthesia, epidural anaesthesia and caudal anaesthesia
2. Peripheral nerve blocks (PNB)\: placement of local anaesthetic agents onto or near peripheral nerves
3. Intravenous regional anaesthesia (IVRA)\: injection of local anaesthetic intravenously into an exsanguinated limb distal to
an occluding tourniquet
4. Topical and in
This article will cover central neuraxial blocks (spinal, epidural and cauda) and peripheral nerve blocks.
Central neuraxial blocks (CNB)
The administration of central neuraxial anaesthesia should only be performed under strict aseptic conditions by trained
sta
Patients are positioned sitting or in the lateral position for the CNB, and the choice between the positions depends on the
provider, the patient, and the procedure.
Spinal and epidural needles are categorised by the design of their tips. Spinal needles may have a bevelled, cutting tip or
a pencil-point, noncutting tip. Epidural needles are larger than spinal needles and have a curved tip to help guide the
catheter in the epidural space.
A CNB can be performed either through a midline or a paramedian approach.
Spinal anaesthesia
In spinal anaesthesia, a thin 9 cm needle is placed through the skin, soft tissue, spinal ligaments, and dura until it reaches
the subarachnoid space and a small amount of local anaesthetic (speci
administered. The subarachnoid injection of a small dose of local anaesthetic can rapidly produce dense surgical
anaesthesia.
Spinal anaesthesia is preferably performed in the lumbar region, below the termination of the spinal cord.
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Figure 1. Spinal needles.
Spread and duration
The density and dose of the local anaesthetic medication determine the spread and duration of subarachnoid anaesthesia.
Local anaesthetics used for spinal anaesthesia are made hyperbaric (denser than CSF) by mixing them with dextrose. In
contrast, plain local anaesthetic solutions are isobaric or slightly hypobaric. Hyperbaric solutions have greater spread in the
direction of gravity and are more predictable with minimal inter-patient variability.
Intrathecal injection of local anaesthetics produces an extensive sympathetic block, leading to a drop in systemic vascular
resistance and blood pressure. Heart rate may increase, decrease, or remain unchanged depending on the level of the
block.
Spinal anaesthesia provides excellent operating conditions for lower abdominal, pelvic, and lower extremity surgery.
Single-injection spinal anaesthesia only lasts up to two to three hours, making it unsuitable for prolonged surgeries.
Epidural anaesthesia
In epidural anaesthesia, a longer and larger needle is used to reach the epidural space, and a catheter is placed through
that needle into the epidural space.
Epidural anaesthesia requires a larger volume of local anaesthetic and takes more time to establish. However, when a
catheter is in the epidural space, a local anaesthetic can be injected repeatedly, and anaesthesia can be prolonged to
match the duration of the surgery.
Figure 2. Epidural needle and catheter
set
Spread and duration
The drug dose, injection site and patient variables are the main determinants of the spread of epidural block. The extent
of the epidural block is proportional to the dose of local anaesthetic injected. The epidural injection can provide a
segmental block.
Hypotension and bradycardia can occur during epidural anaesthesia, and the major risk factors for hypotension are the
extent and onset of sensory block. Faster onset and more extensive block usually increase the probability of hypotension.
3
Epidural can be safely performed in the lumbar, thoracic, and even cervical regions. A thoracic epidural is a useful adjunct
to general anaesthesia for upper abdominal and thoracic surgery and provides intraoperative and postoperative pain
management.
Metraminol, ephedrine and phenylephrine are the most commonly used vasopressors for managing hypotension
associated with neuraxial anaesthesia.
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Figure 3. The epidural space.
Caudal anaesthesia
The caudal space is an extension of the epidural space. Caudal anaesthesia and analgesia are more useful in paediatric
patients.
Complications
Complications of central neuraxial blocks include\:
Technical\: failure of the technique
Direct trauma to nerves and adjacent structures
Haemodynamic instability and high block
Post-dural puncture headache (PDPH)
Meningitis
Epidural haematoma/abscess
Back pain
Urinary retention
Peripheral nerve blocks
Peripheral nerves can be blocked at several points along their paths to provide site-speci
anaesthesia and analgesia.
Local anaesthetic solution is injected as close to a nerve or network of nerves associated with the sensation of an area. A
single injection or catheter can be used, depending on the indication of the peripheral nerve block.
Peripheral nerve blocks can be performed using a variety of guidance techniques. However, ultrasound guidance for
regional anaesthesia has many advantages over other techniques as it allows direct imaging of peripheral nerves, the block
needle tip, and injection distribution.
Peripheral nerve blocks can be used alone as the sole anaesthetic, as a supplement with general anaesthesia, or for
providing prolonged postoperative analgesia.
Upper extremities
The nerve supply to the upper extremity is derived from the brachial plexus. Brachial plexus blocks above the clavicle
target the ventral rami, trunks, and divisions. Brachial plexus blocks below the clavicle target the cords and terminal
nerves.
An interscalene block is used for shoulder surgeries.
A supraclavicular, infraclavicular, and axillary block are used for elbow, forearm, and hand operations.
Trunk blocks
Truncal fascial plane blocks involve the injection of a large volume of local anaesthetics into musculofascial planes that
contain nerves rather than around speci4
An advantage of these blocks is that the injection is distant from
critical structures such as the spinal cord, major vessels or pleura.
The erector spinae plane block, pectoral nerve block, and serratus anterior plane block are interfascial blocks used to
provide surgical and postoperative analgesia to the chest wall.
The transversus abdominis plane block, rectus sheath block, ilioinguinal and iliohypogastric nerve blocks are
interfascial plane blocks used to provide postoperative analgesia following abdominal surgeries.
The intercostal nerve block is mostly performed to provide analgesia following rib fractures and thoracic surgery.
Lower extremities
The nerve supply to the lower extremity is derived from the lumbar and sacral plexuses.
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The femoral nerve block, fascia iliaca block, obturator nerve block, sciatic nerve block, popliteal nerve block and
saphenous nerve block are the most common nerve blocks performed to provide surgical anaesthesia and postoperative
analgesia.
Complications
Complications of peripheral nerve blocks include\:
Technical\: failure of the technique
Direct trauma to nerves and adjacent structures
Drug-related\: local anaesthetic systemic toxicity due to intravascular injection or systemic absorption, allergic reaction
and methemoglobinemia (prilocaine)
Infection
Supraclavicular upper limb blocks\: pneumothorax, ipsilateral phrenic nerve, and recurrent laryngeal nerve palsy
Intercostal block\: pneumothorax
Femoral nerve block\: vascular injury leading to haematoma and arterial pseudoaneurysm
Pharmacology of local anaesthetic drugs
Local anaesthetic drugs reversibly block sodium channels on the neuronal membrane and block the conduction of
impulses, thus producing reversible loss of motor power and sensory sensation.
Local anaesthetics vary widely in their potency, duration of action, stability, solubility, and toxicity. Common local
anaesthetics include lidocaine, bupivacaine, ropivacaine, levobupivacaine, and prilocaine.
Levobupivacaine, an isomer of bupivacaine, has anaesthetic and analgesic properties similar to bupivacaine but has fewer
adverse e
Adrenaline is added to the local anaesthetic solutions to reduce the local blood
the action. 5
However, this should be avoided for blocks of the digits or penis due to the risk of tissue ischemia.
Table 1. Common local anaesthetics and their dosing.
Structural
Onset of
classi
action
Maximum dose (without
vasoconstrictor)
Maximum dose (with
vasoconstrictor)
Lidocaine Amide Fast 3 mg/kg 7 mg/kg
Bupivacaine Amide Moderate 2 mg/kg 2.5 mg/kg
Ropivacaine Amide Moderate 3 mg/kg 3 mg/kg
Levobupivacaine Amide Moderate 2 mg/kg 2.5 mg/kg
Dosing for extreme body weight is calculated based on ideal body weight.
Contraindications
Absolute contraindications to regional anaesthesia include\:
Patient refusal
Localised infection
Allergy to medications used
Relative contraindications to regional anaesthesia include\:
Abnormal anatomy
Coagulation disorders
Antiplatelets and anticoagulants
Neurological disease
Haemodynamic instability
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References
Klein, A.A., Meek, T., Allcock, E., Cook, T.M., Mincher, N., Morris, C., Nimmo, A.F., Pandit, J.J., Pawa, A., Rodney, G. and Sheraton,
T., 2021. Recommendations for standards of monitoring during anaesthesia and recovery 2021\: Guideline from the
Association of Anaesthetists. A n a e s t h e s i a , 7 6 (9), pp.1212-1223.
New York School of Regional Anesthesia.Intravenous Regional Block for Upper and Lower Extremity Surgery. Available
from\: [LINK]
Curatolo, M., Scaramozzino, P., Venuti, F.S., Orlando, A. and Zbinden, A.M., 1996. Factors associated with hypotension and
bradycardia after epidural blockade. A n e s t h e s i a & A n a l g e s i a , 8 3 (5), pp.1033-1040.
Chin, K.J., Versyck, B. and Pawa, A., 2021. Ultrasound‐guided fascial plane blocks of the chest wall\: a state‐of‐the‐art
review. A n a e s t h e s i a , 7 6 , pp.110-126.
BNF. Treatment summary - local anaesthesia. Available from\: [LINK]
Image references
Figure 1. Jojo. S p i n a l n e e d l e s . License\: [Public domain]
Figure 2. Privatarchiv Foto von MrArifnajafov. S e t f o r e p i d u r a l c a t h e t e r i z a t i o n \: p h i l t e r , c a t h e t e r , T u o h y n e e d l e a n d s y r i n g e .
License\: [CC BY]
Figure 3. Leila Kafshdooz et al. E p i d u r a l a n e s t h e s i a . License\: [CC BY]
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