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Diploma in Anaesthesia > Local and regional anaesthesia > Flashcards

Local and regional anaesthesia Flashcards

1
Q

Distinguish local anaesthesia from local infiltration

A

Local anaesthesia is deinfed as the loss of sensation in an area of the body without loss of consciousness.

Used broadly to describe the action of local anaesthetic drugs: including: local infiltration, regional blocks and neuraxial blocks

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2
Q

Define regional anaesthesia

A

RA is characterized by the loss of sensation in a circumscribed region of the body without loss of consciousness

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3
Q

Define neuraxial anaesthesia

A

Placement of local anaesthetic agent adjacent to the structures of the central nervous system or neuraxis

Epidural

  • Cervical
  • Thoracic
  • Lumbar
  • Caudal

Spinal (subarachnoid block)

Combined spinal epidural (CSE)

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4
Q

What is the mnemonic for the discussion regarding informed consent?

A

BRAN

Benefits
RIsks (common and serious)
Alternative strategies
Nothing: what would happen if nothing were done

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5
Q

What are three techniques used in regional anaesthesia to confirm the correct placement of the needle in relation to the nerves

A

Seeking of paraesthesia
Nerve stimulators
Ultrasound guidance (allows visualization of adjacent structures)

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6
Q

List strategies to reduce the risk of LA toxicity

A

Aspiration prior to injection
Fractionated injection - 5 ml aliquots
Slow injection
Communication (Perioral/tongue sensory abnormality/tinnitus)
Do not exceed maximum doses
Recognize techniques with highest absorption
(Intrapleural > Intercostal > Caudal > Epidural > Brachial plexus > Infiltration)

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7
Q

For the process of local anaesthetic toxicity, rank the warning symptoms or signs from initial signs through to the worst possible scenario?

A

WARNING SYMPTOMS
Tinnitus, circumoral or tongue sensory abnormality
Visual disturbance
Muscle twitching

then…

NEUROLOGICAL
Convulsions
Unconsciousness
Coma

then…

CARDIORESPIRATORY
Respiratory arrest
Cardiovascular collapse

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8
Q

Describe the 5 common complications of neuraxial blocks

A
  1. Post-dural puncture headache
  2. Nausea and hypotension
  3. Inadequate block
  4. Shivering
  5. Urinary retention
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9
Q

List important possible serious complications of neuraxial blockade

A

SYSTEMIC LA TOXICITY
- Convulsions/Coma/Respiratory Arrest/CVS collapse

NEUROLOGICAL INJURY

  • Spinal/epidural hematoma
  • Paraplegia
  • Radiculopathy
  • Conus medullaris injury (back pain/jarring/paraesthesia)
  • Cauda equina syndrome (back/leg pain + bowel/bladder)
  • Anterior spinal artery cord syndrome (flaccid paralysis legs with sparing of sensation)

INFECTION

  • Meningitis
  • Spinal/epidural abscess

IMMUNE
- Anaphylaxis

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10
Q

What are the symptoms of conus medullaris injury?

A
  • Conus medullaris injury (Severe back pain. Strange or jarring sensations in the back, such as buzzing, tingling, or numbness.)
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11
Q

What are the symptoms of cauda equina syndrome?

A
  • Cauda equina syndrome (low back pain, pain that radiates down the leg, numbness around the anus, and loss of bowel or bladder control.)
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12
Q

What are the symptoms of anterior spinal cord syndrome?

A
  • Anterior spinal artery cord syndrome (flaccid paralysis of the lower extremities and bowel and bladder dysfunction with sparing of proprioception and sensation, due to the selective ischemia to the anterior portion of the cord.)
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13
Q

Name the 3 absolute contraindications to neuraxial anaesthesia

A

Patient refusal
Local/overlying sepsis
Significant uncorrected hypovolaemia

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14
Q

Name 5 relative contra-indications to neuraxial anaesthesia

A
  1. Coagulopathy/anticoagulant therapy
  2. Aortic/mitral stenosis (Fixed CO state –> profound hypotension from SNS block)
  3. Previous back surgery (technical difficulty)
  4. Systemic sepsis (risk of seeding and abscess)
  5. Pre-existing neurological disease (there may be medicolegal disputes about ‘new’ symptoms
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15
Q

How many days after thrombolysis can neuraxial anaesthesia be administerd

A

If possible avoid block entirely

If not possible to avoid entirely, avoid within 10 days

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16
Q

How long after a standard prophylactic dose of LMWH can a neuraxial block be done

A

Wait until 12 hours after dose

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17
Q

Neuraxial blockade in a patient on high dose/therapeutic LMWH

A

Wait 24 hours after last dose

18
Q

When can neuraxial blockade be commenced in a patient on Warfarin?

A

Stop Warfarin 5 days prior to surgery and ensure INR < 1.5 prior to surgery

19
Q

When should NSAIDs/Aspirin be stopped prior to neuraxial blockade

A

There is no increased risk. These medications can be continued

20
Q

How should clopidogrel administration be altered leading up to neuraxial blockade

A

Stop 7 days pre-block (consult cardiology)

21
Q

What are the platelet cut-off ranges for spinal and epidural anaesthesia

A

Epidural: Platelets > 100 x 10^9/L
Spinal: Platelets >50 x 10^9/L

22
Q

Which technique is more likely to cause bleeding with neural tissue compression: epidural vs spinal

A

Epidural

23
Q

How can hematoma rates be reduced during neuraxial blockade

A 
Smallest needle possible
Do spinal instead of epidural
Only thread the catheter 4 cm into the epidural space
Minimize recurrent passes
Abort the technique if difficult
24
Q

When should a spinal/epidural hematoma be suspected?

A

Severe back pain hours or days after block

OR

Prolonged or abnormal neurological deficit

25
Q

What actions should be taken in the event of symptoms of a spinal/epidural hematoma?

A

MRI and neurosurgical referral

26
Q

What is a major advantage of regional anaesthesia over general anaesthesia

A

Allows patient to be conscious to detect early warning symptoms of complications e.e. TURP syndrome

27
Q

What is TURP syndrome

A

Prostate resection involves irrigation with large volumes of hypotonic fluid. Large volumes of hypotonic fluid can enter the circulation through venous sinuses.
During prolonged/problematic resections –> pulmonary oedema ± cerebral oedema ± hyponatraemia

28
Q

What are the early symptoms of TURP syndrome

A

Restlessness
Headache
Tachycardia
Confusion

Only one of these is present during GA

29
Q

Describe a Bier’s Block (intravenous regional anaesthesia)

A

Proximally inflated cuff with exsanguination of the affected limb. Inflate cuff 20 mmHg above SBP and keep inflated. Inject local anaesthetic through an IV cannula and wait 5 minutes.

30
Q

Why is RA safer than GA for caesarian section?

A

Avoidance of airway instrumentation and risk of hypoxia

  • difficult laryngoscopy (altered maternal anatomy, oedema)
  • rapid desaturation (reduced FRC, increased O2 consumption)
  • Increased reflux/aspiration risk
31
Q

How does RA in C?S improve patient experience

A

Early bonding with child and partner usually allowed in

32
Q

How is outcome affected by RA vs GA in C/S

A

RA - reduced intraoperative bleeding –> better outcomes

33
Q

How is intraoperative bleeding reduced during RA for C/S

A 
Relative hypotension (spinal)
Avoiding volatile agent associated uterine relaxation
34
Q

When GA and RA are combined, should RA be done before or after GA? Explain

A

RA should be done in the awake patient

  1. Paraesthesia/severe pain (awake patient) heralds possible neurological damage
  2. Early warning for LA systemic toxicity (tinnitus/perioral sensory disturbance, muscle twitching)
  3. Anaesthetic versus surgical cause of neurological damage – documentation
35
Q

List 4 circumstances when it might be advantageous to perform RA after GA

A
  1. Paediatric population
  2. Non-compliant adult population (learning disability)
  3. Movement might cause severe pain (epidural for pelvic fracture)
  4. Patient refuses to have RA done awake
36
Q

At max infusion rate state how long it takes for 1L of fluid to infuse in the different cannulae 22G —-> 14 G

A 
22G - 25 mins
20G - 15 mins
18G - 10 mins
16G - 5 mins
14G - 3-4 mins
37
Q

How to detect IA cannulation

A
  1. Pressure transducer (if available)

2. Manometer tubing –> ? height and pulsation

38
Q

Which drugs cause ischaemia/necrosis after inadvertant arterial cannulation and administration

A

Thiopental
ketamine
atracurium
phenytoin

39
Q

What are the consequences of intra-arterial injection of thiopental/ketamine/atracurium/phenytoin into an artery

A

Intense burning
Distal blanching with blisters
Pronounced vasospasm (Rx - papaverine 20 mg)
Endarteritis –> thrombosis/emboli–> distal ischaemia and gangrene

40
Q

What is the treatment of inadvertant intra-arterial drug administration?

A

Leave cannula in
Give vasodilator: papaverine 20 mg through cannula
Give IV heparin
Consider a brachial plexus block (if upper limb) to reduce arterial spasm

Diploma in Anaesthesia (73 decks)

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