Complications of Regional Anesthesia

1
Complications of Regional Anesthesia

• R2 ??? / VS ???
• 96-12-07

2
Complications of Regional Anesthesia

• How to avoid them
• How to manage them

3
Complications of Peripheral Nerve Block

• Uncommon 0.04 5

• Needle related
• Nerve injury
• Damage to surrounding structures
• Vascular puncture
• Drug related
• LA toxicity
• Methhaemoglobinemia

• Catheter related
• Inflammation to infection
• Catheter migration
• Catheter shearing
• Catheter knotting

4
Damage to Surrounding Structures

• Bleeding risks
• Know the anatomy !
• Accidental vascular puncture not uncommon
• Anticoagulated patients
• Removal of catheter 6 hr after last dose of LMWH

Bleeding complications from femoral and sciatic
nerve catheters in patients receiving LMWH.
Anesth Analg. 103 1036-7
5

• Pulmonary complications
• Supraclavicular blocks ? pneumothorax
• Avoid dorsomedial angulation
• Ultrasound visualisation
• Interscalene block ? unilateral diaphragm
  paralysis
• Avoid in patients with severe lung disease

6
LA Toxicity

• Intravascular injection
• Neurological and cardiorespiratory sequelae
• 0.1 0.33
• Bupivacaine gt L bupivacaine gt ropivacaine gt
  lignocaine

7
How to Avoid LA Toxicity

• Fractionated injection
• Communication
• Choose your LA
• Total dose
• Use ultrasound
• Visualise vessels
• Reduced minimum effective dose of LA
• Potential antidote ?

8
Potential Antidote

• Case 1
• Successful resuscitation of a patient with
  ropivacaine-induced asystole
• 200 ml 20 intralipid
• Case 2
• Successful use of a 20 lipid emulsion to
  resuscitate a patient after a presumed
  bupivacaine-related cardiac arrest
• 100 ml 20 intralipid

Anesthesia. 2006 61 800-1
Anesthesiology. 2006 105 217-8
9
Lipid for LA Toxicity

• Proposed mechanism of action
• Lipid emulsion creates lipid phase which extracts
  the lipid soluble bupivacaine molecules from the
  aqueous plasma phase
• Lipid infusion diffuses directly into tissues and
  interacts with bupivacaine
• Accelerates bupivacaine decline in myocardial
  content and speeds recovery from bupivacaine
  induced asystole

10
Controversy

• Inability to perform clinical trials due to small
  numbers
• Can only wait for clinical reports
• The use of lipids last ditch effort in patient
  who does not respond to resuscitation and is
  effectively dead

11
Intralipid for LA Toxicity Tx

• Only after standard resuscitation method fail
• 1.5 ml/kg as initial bolus, followed by
• 0.25 ml/kg/min for 30-60 minutes
• Bolus could be repeated 1-2 times for persistent
  asystole
• Infusion rate could be increased if the BP
  declines

12
Infection

• Uncommon
• More often colonization
• Predisposing factors
• Stay in ICU
• Continuous peripheral nerve block gt 48 hr
• Male
• No antibiotic prophylaxia
• Prevention

Anesthesiology. 2005 103 1035-45
13
Catheter Knotting

• Retrieval of knotted catheters
• Reposition patient to minimise tension on
  surrounding tissues and gentle traction
• Fluroscopic guidance
• Guidewire ? unwind knot
• Dilator sheaths of increasing size pass over
  catheter ? retract catheter into sheath

14
Nerve Injury

• Injected intrafascicularly
• ? Mechanical destruction of the fascicular
  architecture
• ? Inflammation, cellular infiltration, axonal
  degeneration
• ? Nerve scaring
• ? Sensory, motor dysfunction
• How to avoid ?

15
Needle Design

• Short bevel needle
• 35 40 angle
• ?risk of perforating a nerve
• Most commonly use in PNB
• But greater damage if penetrate nerve

• Long bevel needle
• 10 15 angle
• Clean cuts, more likely to heal

16
Nerve Stimulator

• Current-needle relationship
• gt 1 mA needle too far from nerve
• lt 0.1 mA possible intraneural needle
• Most frequently used 0.2 0.5 mA
• Ultrasound
• Facilitate nerve localisation
• But not good enough to visualise nerve fascicles
  to prevent intra-fascicular injections

17
Suitable Needle Length for Each Block
18
Avoid High Pressure Injection

• gt 20 psi may indicate intrafascicular injection
• Always use same syringe/needle size to develop a
  feel
• In-line monitoring of the injection pressure

19
Epineurium or Perineurium

• Ultrasound cannot distinguish sub-epineurium vs
  sub-perineurium injection

20
Stop if Pain !

• 14 of patients experienced paresthesia but later
  analysis failed to show paresthesia as a risk
  factor for post-op neurologic dysfunction
• 2 neurologic injuries after paresthesia occurred,
  although the anesthesiologist involved stopped
  injection when the patients reported pain

Anesth Analg. 199988 847-52
Anesthesiology. 1997 87 479-86
21
Surface Localisation

• Know the surface anatomy
• Ultrasound visualisation
• Percutaneous localisation

22
Dose U/S Reduce Nerve Injury ?

• Noted nerve expansion on U/S after 1-2 ml dye
  injected intra-neurally in pig brachial plexus
  nerves
• Prelim results difficult to support that U/S
  reduce nerve injury. Low incidence large study
  population needed
• Intra-neural injection reported during U/S

Anesth Analg. 2005 101 610-1
Anesth Anlag. 2007 104 1009
Anesth Analg. 2004 99 627-8
23
Block under GA/Sedation Safe ?

• No study comparing risks of nerve injury between
  awake vs asleep patients
• Proponents of GA/sedation
• Better patient acceptance and comfort especially
  deep blocks
• Paediatric patients always GA

24

• Opponents to GA/sedation
• Awake patients will complain of pain when
  intra-neural injection
• But
• Pain not always present
• Too late
• Normal discomfort vs abnormal pain
• ? Judicious sedation

25
In Summary

• Short bevel needles
• Suitable length for each block
• Slow advancement
• Working nerve stimulator
• Avoid injecting if high pressure
• Dont inject if pain
• Match LA duration concentration to procedure
• Protection
• Routine U/S ?
• Blocks under GA?

26
Complications of Regional Anesthesia

• How to avoid them
• How to manage them

27
Incidence of Neural Complications

• 0 5
• Brachial plexus more common (axillary injury)
• Most minor complications
• Difficulty definitive diagnosis

28
Nerve Injury

• Paraesthesia vs no paraesthesia
• Post-op deficit
• Slight hypersensitivity to severe paresis
• 2 weeks to 2 years
• Near complete resolution at 4 weeks

29

• Standard paraesthesia technique common post-op
  paraesthesia (19)
• Transarterial axillary block 0.2 neural
  complications, but 1.4 arterial spasm, hematoma,
  unintentional intravascular injection
• Stimulator serious neural injury has been
  reported
• No evidence to endorse one to another

30
What to Do ?

• Index of suspicion, follow up
• Complete clinical examination document extent
  of lesion
• U/S or MRI
• EMG and ENMG
• May be normal within first days after insult
• Repeat 4 weeks and then 6 months
• If normal ENMG, to observe clinically

31
Documentation

• Record of
• Which nerves stimulated
• With which impulse duration
• At which minimum current intensity
• Any pain or paresthesia during the procedure
• Measures taken
• Presence/absence of pain during LA injection

32
Treatment for Nerve Injury

• Surgical management of nerve transection
• If hematoma, surgical opinion
• Vit B complex, Neurobion, Neuroforte
• Anti-neuropathic agents
• Gabapentin, Pre-gabalin
• Tricyclics antidepressant
• Treat CPRS (complex regional pain syndrome) early
  rather than late

33
Treatment of Neuropathic Pain
34
Im your regional anesthesiologist, and hes my
back-up man !

• 
  Thanks
• 
  very much !