Local and regional anaesthesia Flashcards
Distinguish local anaesthesia from local infiltration
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
Define regional anaesthesia
RA is characterized by the loss of sensation in a circumscribed region of the body without loss of consciousness
Define neuraxial anaesthesia
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)
What is the mnemonic for the discussion regarding informed consent?
BRAN
Benefits
RIsks (common and serious)
Alternative strategies
Nothing: what would happen if nothing were done
What are three techniques used in regional anaesthesia to confirm the correct placement of the needle in relation to the nerves
Seeking of paraesthesia
Nerve stimulators
Ultrasound guidance (allows visualization of adjacent structures)
List strategies to reduce the risk of LA toxicity
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)
For the process of local anaesthetic toxicity, rank the warning symptoms or signs from initial signs through to the worst possible scenario?
WARNING SYMPTOMS
Tinnitus, circumoral or tongue sensory abnormality
Visual disturbance
Muscle twitching
then…
NEUROLOGICAL
Convulsions
Unconsciousness
Coma
then…
CARDIORESPIRATORY
Respiratory arrest
Cardiovascular collapse
Describe the 5 common complications of neuraxial blocks
- Post-dural puncture headache
- Nausea and hypotension
- Inadequate block
- Shivering
- Urinary retention
List important possible serious complications of neuraxial blockade
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
What are the symptoms of conus medullaris injury?
- Conus medullaris injury (Severe back pain. Strange or jarring sensations in the back, such as buzzing, tingling, or numbness.)
What are the symptoms of cauda equina syndrome?
- Cauda equina syndrome (low back pain, pain that radiates down the leg, numbness around the anus, and loss of bowel or bladder control.)
What are the symptoms of anterior spinal cord syndrome?
- 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.)
Name the 3 absolute contraindications to neuraxial anaesthesia
Patient refusal
Local/overlying sepsis
Significant uncorrected hypovolaemia
Name 5 relative contra-indications to neuraxial anaesthesia
- Coagulopathy/anticoagulant therapy
- Aortic/mitral stenosis (Fixed CO state –> profound hypotension from SNS block)
- Previous back surgery (technical difficulty)
- Systemic sepsis (risk of seeding and abscess)
- Pre-existing neurological disease (there may be medicolegal disputes about ‘new’ symptoms
How many days after thrombolysis can neuraxial anaesthesia be administerd
If possible avoid block entirely
If not possible to avoid entirely, avoid within 10 days
How long after a standard prophylactic dose of LMWH can a neuraxial block be done
Wait until 12 hours after dose