Ian Seppelt: Time is Brain: The Neurocritical Airway

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

http://www.das.uk.com

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

http://www.das.uk.com

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.

seppelt@med.usyd.edu.au

Questions?