The Neurocritical Airway
Dr Ian Seppelt FANZCA FCICMDept of Intensive Care Medicine, Nepean
Hospital,and George Institute for Global Health,
University of Sydney and Neuroanaesthesia Division, Dept of
Anaesthesia, Macquarie University
What might scare you?
1. Airway management with a broken neck
2. Airway management in acute SAH
Basic Principles• Stick to what you are used to and are good at
– Most experienced person available
• Assess the airway properly first
• Have Plan A, B and C prepared, articulated and thought through
• It is (almost) impossible to intubate with a correctly fitting cervical collar
• Consider what ‘neutral’ position means
– Get position right first [in sex, real estate and anaesthesia]
Any history? MNO
Medic Alert/ Notes/ Old Trache
Predict Difficult Ventilation - BONES
Beard Obese No Teeth
Elderly Snores
Predict Difficult Laryngoscopy – Four Ds
Distortion Dentition
Disproportion Dysmobility
Airway Assessment
Plan A:Initial trachealintubation plan
Plan B:Secondary trachealintubation plan
Plan C:Maintenance of oxygenation, ventilation,postponement of surgery and awakening
Plan D:Rescue techniquesfor "can't intubate, can't ventilate" situation
Direct laryngoscopy
failed intubation
succeed
succeed
succeed
Tracheal intubation
ILMATM or LMATM
failed oxygenation
failed oxygenation
Revert to face maskOxygenate & ventilate
LMATM
increasing hypoxaemia
or
fail
Cannulacricothyroidotomy
Surgicalcricothyroidotomy
improved oxygenation
Awaken patient
Confirm - thenfibreoptic trachealintubation throughILMATM or LMATM
Postpone surgeryAwaken patient
failed intubation
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Unanticipated difficult tracheal intubation - during rapid sequenceinduction of anaestheia in non-obstetric adult patient
failed intubation
Tracheal intubation
Directlaryngoscopy
Any problems
Call for help
Plan A: Initial tracheal intubation plan
Plan B not appropriate for this scenario
failed oxygenation(e.g. SpO2 < 90% with FiO2 1.0) via face mask
Pre-oxygenateCricoid force: 10N awake 30N anaesthetisedDirect laryngoscopy - check: �Neck flexion and head extension �Laryngoscopy technique and vector �External laryngeal manipulation - �by laryngoscopist �Vocal cords open and immobileIf poor view:� Reduce cricoid force� Introducer (bougie) - seek clicks or hold-up� and/or Alternative laryngoscope
Use face mask, oxygenate and ventilate1 or 2 person mask technique(with oral ± nasal airway)Consider reducing cricoid force if ventilation difficult
LMATM
Reduce cricoid force during insertionOxygenate and ventilate
failed ventilation and oxygenation
Plan D: Rescue techniques for"can't intubate, can't ventilate" situation
Difficult Airway Society Guidelines Flow-chart 2004 (use wit h DAS guidelines paper)
Not more than 3 attempts, maintaining:(1) oxygenation with face mask(2) cricoid pressure and(3) anaesthesia
Maintain 30N cricoidforce
Verify tracheal intubation(1) Visual, if possible(2) Capnograph(3) Oesophageal detector"If in doubt, take it out"
Postpone surgeryand awaken patient if possibleor continue anaesthesia withLMATM or ProSeal LMATM - if condition immediately life-threatening
Plan C: Maintenance of oxygenation, ventilation,postponement of surgery and awakening
succeed
succeed
succeed
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Neutral position
Hyperextension
Hyperflexion
Morbidly Obese - Intubation
Morbidly obese patient, head on one pillow(Anesthesia for Obstetrics, 3rd Ed, Sol M Shnider)
Same patient with shoulders and occiput elevated - can now assume the “sniffing the morning air” position
(Anesthesia for Obstetrics, 3rd Ed, Sol M Shnider)
Morbidly Obese - Intubation
Incidence of cervical injury
• Between 1 and 3% of pts admitted with blunt trauma have a cervical fracture– 20% are missed on lateral C/Spine
– 7% missed on trauma series
Baltimore Shock Trauma Database
• SCIWORA
• Ligamentous injury, esp transverse ligament of dens, < 1:1000 incidence
No neurological sequelae …
Anaesthetic implications
• Cervical spine is either definitively cleared or it is not
• If intubation or surgery is urgent then by definition the neck is not clear– Treat as if unstable cervical spine
– No well documented case of new spinal cord injury after properly conducted trauma intubation
– Large forces required to cause damage
Approach
• Neutral position, remove collar
• Manual in-line stabilisation
• Pre-oxygenate
• Drugs: thiopentone or (careful) propofol
• NMBAs: suxamethonium or rocuronium
– Sugammadex available if using aminosteroids
• Place of videolaryngoscopy
– Magrath Mac or Storz C-MAC [choice of Mac and D blades]
Are nasal tubes an option?
The facts
• 3 reported cases of nasocranial intubation– 2 uncontrolled tubes in acute trauma
Horellou et al, Anaesthesia, 1978, 33:73
Marlow et al, J Emerg Med, 1997, 15:187
– 1 routine neonatal intubation
Cameron, Arch Dis Child, 1993, 69:79
• Inexperienced operators, unusual circumstances
Planned maxillofacial surgery?
Goodisson, Shaw and Snape, Intracranial intubation in patients with maxillofacial injuries associated with base of skull fractures, J Trauma, 2001, 50:363
– Nasotracheal tubes are safe in absence of midline anterior skull base fracture
– Even in these, gentle intubation over a bronchoscope or bougie is safe in skilled hands
– Tracheostomy rarely required
• (Awake) Blind nasal intubation
• (Awake) Fibreoptic intubation
• Retrograde intubation
• Emergency or elective surgical airway
Other options?
Guiding ETT into the nasopharynx
• Do not use force (firm but gentle pressure)
• Cephalad distraction of the tube
• Rotation / Malleable introducers
• Suction catheter brought out of the mouth
Retrograde intubation
ILMA✤ ILMA (Fastrach)
☛ Easy insertion
☛ No neck movement
☛ Tube insertioneasy
☛ Airway protected by cuffed ETT
Principles of airway management
1. Secure definitive airway
2. Avoid hypoxia and hypotension
3. Avoid hypertensive response to laryngoscopy
4. Basically, just keep the BP where it is, okay (+/- 10%) ……
Preparation
• Assessment, plans A,B,C,D
• Some degree of hypertension is normal physiological autoregulation– Hypotension = brain ischaemia
• Arterial line pre-induction if possible
Rebleeding
• Unsecured aneurysms:
– 4% rebleed on day 0
– then 1.5%/day for next 13 days [� 27% for 2 weeks]
• Not on my shift ….
• Be ready to actively manage hypotension AND hypertension– SNP infusion, esmolol
– Nimodipine
– Noradrenaline infusion
BP in unsecured aneurysms
Choice of drugs for intubation
• Pretreatment – lignocaine IV or tracheal?
• Opioids – fentanyl, or remifentanil infusion
• Induction agent – thiopentone or propofol or ketamine
– Ketamine??? Are you serious??
• Neuromuscular blocker – sux vs aminosteroid
• Subsequent sedation – drugs that will wear off
– Neurological examination
– Propofol, remifentanil
Lignocaine pretreatment
• Controversial – used to prevent BP and ICP rises due to coughing and straining.
• Contradictory evidence for neuroprotection in cardiac surgery
• Some evidence for neuroprotection in decompression illness
Do the risks outweight the benefits?
Lignocaine in cardiac surgery
• Answer: don’t know
• Pro argument: – Probably safe and possibly beneficial
• Con argument:– Evidence of hypotension lasting several
minutes
– Time-course to effect
– 1.5 – 2.0 mg/kg probably insufficient anyway
Lignocaine for neuroprotection in TBI and SAH
Ketamine and ICP
• Small series from 1970s suggest elevated ICP
• More recent data contradicts this
• Weak evidence of neuroprotection
But thiopentone and propofol have clear evidence of neuroprotection
Harm from oversedation
• ‘Neuroemergency’ patients are best managed with minimal sedation allowing clinical examination
– After immediate resuscitation and stabilisation phase complete
– Midazolam and esp ‘Morphazolam’ or ‘Fentazolam’ saturate fat stores and have very long elimination times
– Adverse neurosychological effects of BZDs
– Propofol and remifentanil unique with extrahepatic clearance and short T1/2cs
Summary
Airway management in neuroemergencies
1.Don’t panic
2.Proper assessment – right time, right place, right people?
3.No clear indication for ‘neuroprotectants’
4.Maintain cerebral perfusion and keep BP close to baseline
5.Do what you are good at.
