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Anaesthesia > Overview of Regional Anaesthesia > Flashcards

Overview of Regional Anaesthesia Flashcards

1
Q

Concepts of Regional Anaesthesia

A

RA affects one part of the body only
Provides 2 parts of the Anaesthetic Triad: Analgesia
Muscle Relaxation
No Hypnosis (additional sedation may be given

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2
Q

Benefits of Regional Anaesthesia

A 
Pre-emptive analgesia
Post-op analgesia
Haemodynamically stable  (caution: neuraxial)
Rapid recovery post-op
Reduced surgical stress response
Reduced GA complications
Avoids airway instrumentation and its complications
Reduced PONV
Reduced DVT in ortho
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3
Q

Patient Preparation

A

As for general anaesthesia
Full history, examination and relevant special investigations
StNil per os
Adequate IV access

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4
Q

Theatre preparation

A 
Anaesthetic machine checked
or ability to ventilate and give O2
Airway trolley
Defibrillator 
Suction
Anaesthetic drugs
Emergency drugs
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5
Q

Types of Regional Anaesthesia (WP2IC or TWINP2)

A 
Topical
Wound infiltration
IV RA of the Arm (Bier's Block)
Peripheral Nerve blocks
Plexus blocks
Central Nerve Block (Neuraxial Blockade)
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6
Q

Topical Anaesthesia

A

Aerosolised
2% lignocaine in MacIntosh sprayer for vocal cords
Topical Cream
Direct Application (DROPS)
Used in minor eye surgery, laryngoscopy and bronchoscopy, incision and drainage of quinsy (tonsil) venepuncture

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7
Q

Wound Infiltration

A

Subcutaneously
Often given into wounds at the end of surgery, under GA
Provides some postoperative analgesia
Wound infusion catheters can give hours of postoperative pain relief
Intradermally
Suturing of wounds
Local before siting of large IV lines, central lines, arterial lines, spinals & epidurals

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8
Q

IV regional anaesthetic of the Arm

A

Provide intense anaesthesia for short surgical procedures (<45-60secs)
Used for surgery of the hand. lower forearm (colle’s fracture)

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9
Q

Peripheral nerve blockade

CAN BE DONE UNDER NERVE STIMULATION/ULTRASOUND

A 
Single nerve blocks:
Femoral, popliteal, radial etc.
Plexus blocks:
Brachial plexus blocks, e.g. 
	Supraclavicular (forearm surgery)
	Interscalene (shoulder surgery
Deep Infiltration:
Transversus abdominus plane block (TAP block)
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10
Q

The Neuraxial Blocks (SPINAL ANAESTHESIA)

A

Local anaesthetic is injected into the CSF in the subarachnoid space
Rapidly acting
Achieves both sensory and motor block
Can provide sufficient anaesthesia for surgery

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11
Q

The Neuraxial Blocks (EPIDURAL ANAESTHESIA)

A

Local anaesthetic is injected into the more superficial epidural space
Takes longer to work
Primarily provides sensory blockade
Usually not good enough to provide full surgical anaesthesia
Usually combined with general anaesthesia

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12
Q

The Neuraxial Blocks (SPINAL ANAESTHESIA) Applied anatomy

A

LA deposited into CSF
Blockade of nerve roots as they pass through the subarachnoid space
Subarachnoid space is deep to the dura and arachnoid mater
Spinal portion of SAS extends from foramen magnum superiorly to S2 inferiorly
Spinal cord ends at L1/2
Use 18G and 16G iv line and place the needle at L3/L4 or L4/L5 use tuffliers line

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13
Q

The Neuraxial Blocks (EPIDURAL ANAESTHESIA) Applied anatomy

A

Epidural space lies outside dura, LA placed into the epidural space at lumbar or thoracic level, via epidural catheter
The nerve roots pass through this space as they leave the spinal cord
The epidural space is a potential space with a negative pressure
Contains: fatty connective tissue, lymphatics and a venous plexus

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14
Q

Indications for Neuraxial Blocks

A

Spinal—usually as sole technique for anaesthesia

Epidural—usually combined with GA for analgesia

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15
Q

Applications for Neuraxial Blocks

A 
Lower abdominal surgery
Inguinal surgery
Urology
Gynaecology
Obstetrics (Caesaran section–spinal; Labour–epidural)
Lower extremity surgery
Lower rectal / perineal surgery
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16
Q

Contra-indications: NeurBlocks ABSOLUTE

A 
Patient factors:
Patient refusal
Inability to give consent
Allergy to LA
Logistical issues:
Inexperienced operator
Inability to give GA
Local infection at the site
Coagulopathies:
Platelets < 75; INR > 1.5
Anticoagulant medication
Severe hypovolaemia
Raised intracranial pressure
Fixed Cardiac Output States:
severe AS or MS
HOCM
17
Q

Contra-indications: RELATIVE

A 
Systemic sepsis
Uncooperative patient:
Psychiatric
Blind / Deaf
Mentally challenged
Pre-existing neurological deficits
Regurgitant valvular heart lesions
Severe spinal deformity
Previous spinal surgery
Complicated surgery where block would not last long enough or be inappropriate
18
Q

Complication LA

A 
Hypotension — common (especially spinal)
High spinal
Post-dural puncture headache
Meningitis, epidural abscess
Epidural and spinal haematoma
Neurological sequelae
Urinary retention
Pruritis (from opioids)
Shivering
Backache
19
Q

Complication of LA

Hypotension

A

Sympathetic blockade leads to vasodilatation
Vasopressors
Ephedrine: 5mg bolus
Phenylephrine: 50ug bolus
Adrenaline if unresponsive to above measures

IV FLUIDS
20
Q

Complication of LA

The high spinal

A 
Presentation:
Severe hypotension
Bradycardia
	Blockade of the cardiac accelerator fibres
Difficulty breathing
Loss of consciousness
Management:
IV Fluids
Vasopressors
Atropine
Intubation and ventilation
Adrenaline
21
Q

Complication of LA

Post-dural puncture headache

A 
Mechanism:
CSF leak from a hole in the dura left by the needle
Traction on dura
Meningitis-like headache
Treatment:
Conservative
	Bedrest
	IV Fluids
	Simple analgesia
	Opiates
	Laxatives
Epidural Blood Patch
	High success rate of cure
22
Q

Complication of LA

Neurological Sequelae

A

Neuropraxias:
Transient
Nerve root damage from needle

Paralysis:
Direct damage
Epidural haematoma or abscess (compression)
	Monitor patient for return of motor function
	Emergency
	Urgent MRI
	Must be released within 6 hours
	Laminectomy / drainage
23
Q

Factors influencing the height of the block

A 
Patient position or posture
Specific gravity of solution
Volume of drugs
Volume of CSF
Site (interspace)
Force &amp; rate of injection
Barbotage
Age, height, weight
24
Q

Specific Gravity

A

CSF has a SG of 1,004.

Solutions with a higher SG (heavier) with sink in the SAS, they are gravity-dependent

Hyperbaric: “heavy” solutions - bupivacaine with dextrose
Isobaric: plain bupivacaine or lignocaine

25
Q

Opioids as additives

A 
Fentanyl or morphine usually in SA
Effect:
Extends the duration of action
Enhances analgesia
Can be used alone, without LA, to give analgesia (block sensory nerves only)
Side-effect: pruritis, can be severe
26
Q

Epidural Anaesthesia

Advantages

A

Placement of epidural catheter allows for a constant infusion or top-up doses
PCEA: Patient-controlled epidural anaesthesia
Opiates enhance post-operative analgesia
Graded block – slow establishment of level avoids the rapid haemodynamic changes

27
Q

Applications of Epidurals

A 
With GA
Thoracic epidural for thoracic surgery
Abdominal surgery
Hip and leg surgery
Labour epidural for analgesia
Post-op analgesia
Chronic Pain treatment

Anaesthesia (15 decks)

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