Airway Planning

Oxygenation > Intubation
Optimise before you compromise
Consider awake intubation in the presence of predictors of difficult airway

The goal of airway management is to maintain oxygenation and ventilation, without physiological compromise or complications, ideally with a patent and protected airway.

This does not (necessarily) imply intubation
Oxygen can be delivered by:
- Ventilation
- Insufflation
- Apnoeic absorption
The chosen airway management technique will depend on the patients anatomy and physiological state, the situation, and the indication
Secondary goals include:
- Airway protection
  From aspiration.
- Airway security
  From dislodgement or obstruction.
- Ventilation
  For acidosis.
- Control of airway pressures
- Control of respiratory timing

The hierarchy of intubation needs:

Epidemiology of Airway Complications

The most common cause of airway related death is hypoxia
- Aspiration is the most common cause of airway related anaesthetic death
Complications from airway management are more common in ED and ICU
Failed tracheal intubation occurs in:
- ~1/1000-2000 elective cases
- ~1/250 obstetric RSI
- ~1/100 ED intubations
Failed or difficult tracheal intubation was the primary event in >1/3^rd of events
CICO occurs in ~1/50,000 elective anaesthetics
- CICO is low compared to incidence of difficult intubation
CICO contributes 25% of anaesthesia-related mortality
Requirement for emergency FONA ↑ morbidity 15x
- ~25% permanent harm or death
In 2/3^rds of CICO situations, a surgical airway was performed too late to prevent harm

Factors Contributing to Adverse Airway Events

Human factors
Human failures occur in ~80% of airway events.
- Delayed decision to declare failed airway
- Delay in decision to perform cricothyrotomy
- Equipment knowledge
- Training
  Especially in surgical airway and rescue techniques.
- Poor communication
- Poor teamwork
- Tunnel vision/task focus
- Training
- Systems
Patient Factors
- Obesity

Important technical factors include:

Make the first attempt the best attempt
- Subsequent attempts are less successful
- Efficacy of SAD rescue is reduced with more attempts
Equipment and technique
- Selection of laryngoscopes, and experience in their use
- Bougie
  Pre-shaped.
- ELM
- Remove cricoid pressure if view is poor
Call for help early
Maximum of 3 attempts by a single provider

A Framework for Airway Management

There are many frameworks for airway management. This one aims to:

Focus on a general plan but not on any specific technique
Provide an approach that is appropriate for elective anaesthesia as well as emergency airway management
Plan for and avoid the difficult airway
In the patient who does not require immediate intubation

Plan
- Evaluate what techniques are available
  Based on the equipment, the patient, and technical skills. Think ACORNS:
  - Awake
    - Waking the patient
    - Awake laryngoscopy
    - Awake FOI
      Is there laryngeal or tracheal pathology?
  - Cricoid/FONA
    - Scalpel cricothyrotomy
    - Needle cricothyrotomy
  - Oral
    - Mask ventilation
    - Intubation
      With and without VL.
  - Nasal
    Is the oral route impossible?
    - Intubation
      Including blind.
  - Supraglotic
    - Use of LMA
    - Use of iLMA
- For this patient, consider which techniques are:
  - Preferred
    Depending on the indication for airway management. In most critical care situations (compared to elective anaesthesia), this will be a definitive oral airway.
  - Feasible
    Could be used to maintain oxygenation +/- ventilation, but may not necessarily be definitive.
  - Unfeasible
    Certain techniques may not be appropriate in certain patients.
- Of this short-list of options, decide on a hierarchy of techniques
  Plan for failure and have a series of identified rescue techniques, including a plan for:
  - Rescue ventilation
    Alternate device, e.g. LMA, iLMA.
  - Rescue intubation
    Alternate device.
- Consider which drugs will be required for these techniques
Patient
Adequate patient preparation prior to induction reduces incidence of difficult tracheal intubation. Think PROC:

Positioning
- Ensure EAM is level with sternal notch to maximise ease of intubation
- Ramping ↑ FRC in the obese patient
Recruitment
Use of CPAP during preoxygenation prolongs safe apnoea time in obese patients.
Oxygenate
Involves adequate denitrogenation, and consideration of apnoeic oxygenation.
- Preoxygenation/denitrogenation
  EtO₂ > 80% indicates a good proportion of FRC is oxygen, significantly prolonging safe apnoea times from 1-2 minutes up to 8 minutes.
  - Note that reduced FRC (e.g. atelectasis) will lead to shunt and rapid drop in SpO₂ despite a high ETO₂ fraction
    Significant shunt will result in an SpO₂ of < 100% despite adequate ETO₂.
  - This can only be achieved when breathing oxygen through a closed-circuit system
- Apnoeic oxygenation
  Delivery of oxygen via nasal cannula during the apnoeic period. This technique:
  - Requires a patent airway
    May not help during the apnoeic period when airway tone is reduced.
  - May be performed with:
    - Standard nasal cannula from wall oxygen at 15L.min^-1
    - Humidified
  - May be useful when:
    - FRC/ is compromised
    - Laryngoscopy is difficult

Perform
- Complete pre-airway management checklist
  During pre-oxygenation periods.
- Begin!

Airway Management Mental Checklist

A good mental checklist should be:

Easy to remember
Allows it to be used as a ‘challenge-confirm’ checklist - i.e. the steps can be performed by multiple providers simultaneously and then the checklist is used to verify tasks have been completed
Appropriate to be used by a single provider as a ‘call-do-response’ checklist when working with an unfamiliar team

The SPEEDBOMB checklist:

There are many different checklists - I like this one. I routinely perform it during the pause that is provided during pre-oxygenation.

Suction
- Available
- Consider gastric drainage if NGT is in situ
Position
In optimal position for this particular technique.
- Ear-to-sternal notch
End-tidal CO₂
Available and working.
Equipment
The kit needed for the chosen techniques.
- BVM
  With mask and PEEP valve.
- Airway adjuncts
  NPA and OPA available.
- Laryngoscope
  - Two working laryngoscopes
  - Lubricated
    Critically ill patients often have high sympathetic tone and a dry oropharynx, making advancement of an unlubricated blade down the tongue difficult.
  - Appropriate sized blades
- LMA
  Lubed and inflated as desired.
- ETT
  - Of appropriate size
  - Lubricated
  - At least two, including a smaller one
  - If concerned about upper airway pathology/burns, have a size 6 available
- Adjuncts to ETT
  - Bougie
    Must always be available.
  - Stylet
  - Syringe
    For cuff inflation.
Drugs
Including desired dose.
- Induction agents
- Muscle relaxant
  If concerned, always use adequate doses of a rapid-onset NMBD.
- Opioid
- Vasopressors
Backup plan
Double check the availability of backup equipment, including FONA equipment.
Oxygen
- Supply present and connected
  Ensure that the oxygen tubing attached to the flowmeter is also attached to the patient.
- Adequate pre-oxygenation/denitrogenation period
- Use of PEEP for lung recruitment prior to induction
Monitoring
- ECG
- SpO₂
- BP
Briefing
- Allocate roles
- Detail airway plan A, B, etc
- Declare at what points the airway management strategy will change
  e.g. “If the SpO₂ falls to less than 93%, I will cease intubation attempts and return to BVM. If unable to mask ventilate, I will place an LMA.”

References

Nickson, C. The challenge of the critically ill airway. 2018. CIA Course Notes.
Mommers L, Keogh S. SPEEDBOMB: a simple and rapid checklist for Prehospital Rapid Sequence Induction. Emerg Med Australas. 2015 Apr;27(2):165-8.
Chrimes, N. Fritz, P. The Votex Approach: Management of the Unanticipated Difficult Airway. Smashwords. 2013.
Levitan, R. The Airway Cam Guide to Intubation and Practical Emergency Airway Management. 1st Ed. 2004.