NAP4 Project
Assessment and planning
Dr Adrian Pearce
Guy’s and St Thomas’ Hospital
London
An elderly patient presented for an elective video-assisted thoracic
procedure.
No airway assessment was undertaken and (consequently) no airway
management problem was anticipated preoperatively.
After induction of anaesthesia, including muscle relaxation, direct
laryngoscopy was very difficult with the report noting ‘limited neck
extension and prominent teeth’.
Multiple attempts at intubation failed, the procedure was abandoned and a
SAD inserted. On return of spontaneous breathing and awakening the
SAD was removed but the oxygen saturations remained low.
After 10 minutes with oxygen saturations in the 80s, the cardiothoracic
surgeon inserted a percutaneous tracheostomy.
‘An anaesthetist must assess the patient before anaesthesia and devise an
appropriate plan of anaesthetic management’ - The Good Anaesthetist, Royal
College of Anaesthetists, 2010.
‘The preoperative assessment process should have identified and addressed
problems with individual patients.’ – Pre-operative Assessment and Patient
Preparation, Association of Anaesthetists of Great Britain and Ireland, 2010.
NAP 4 Project
133 Anaesthesia forms
28 reports airway assessment ‘not
recorded’
9 reports field left blank
~ 25% reports had no written
information on airway assessment
‘A minimum examination of dental
health, inter-dental distance and
mandibular protrusion should be
routine.
It would be unconscionable to find
that a patient had an interdental
distance of only 1 cm after induction’
Dr Ian Calder, 2011
133 Anaesthesia reports
Difficulty with airway management anticipated 66
not anticipated 67
Anticipated problems
Difficult direct
laryngoscopy/intubation
56
Difficult facemask
21
Anticipated problems allow
planning
Difficult direct access
18
but
Difficult SAD
10
The adopted strategy must
be likely to deal with the
anticipated problems in the
safest/best way
Difficult preoxygenation
8
A non-obese adult with trismus was scheduled for removal of infected
mandibular plate during daylight hours.
The anaesthetist assessed the airway and anticipated that problems
would be present in this airway compromised by pharyngeal oedema,
radiotherapy and infection.
The specific problems identified were difficult facemask ventilation,
difficult direct laryngoscopy/intubation, difficult SAD insertion and
difficult direct tracheal access. Patient cooperation was not expected to
be a problem.
Anaesthesia was induced and rocuronium administered. After
unsuccessful attempts at fibreoptic intubation and with difficult
ventilation (oxygen saturations falling to 25%) the airway was eventually
rescued by difficult surgical tracheostomy.
Difficult direct laryngoscopy and difficult facemask ventilation
= secure airway awake
An adult patient with ankylosing spondylitis required surgery during
daylight hours for intestinal obstruction.
Difficult direct laryngoscopy and risk of aspiration were predicted
by the consultant anaesthetist.
The patient was managed by a rapid sequence induction with
propofol, suxamethonium and cricoid force.
When intubation by direct laryngoscopy was not possible
rocuronium was administered and attempts were made to intubate
through a SAD with a flexible fibrescope.
When this also failed further relaxant was administered and the
laparotomy was carried out with a SAD.
The induction process took 1 hr.
Difficult direct laryngoscopy and risk of aspiration
= secure airway awake
An adult patient with ankylosing spondylitis required surgery during
daylight hours for intestinal obstruction.
Difficult direct laryngoscopy and risk of aspiration were predicted
by the consultant anaesthetist.
The patient was managed by a rapid sequence induction with
propofol, suxamethonium and cricoid force.
When intubation by direct laryngoscopy was not possible
rocuronium was administered and attempts were made to intubate
through a SAD with a flexible fibrescope.
When this also failed further relaxant was administered and the
laparotomy was carried out with a SAD.
The induction process took 1 hr.
Failed intubation at RSI and non-emergency
= wake-up patient
NAP4 identified these unanticipated clinical situations as the ones for
which all anaesthetists should have a prepared strategy
Failed direct laryngoscopy
Failed ventilation
Failed intubation at RSI
Aspiration with SAD
Loss of airway with SAD
Extubation/recovery problems
A strategy is a combination of plans constructed
specifically to deal with a problem
The more commonly the adopted strategy is a national or locally agreed
one, the greater likelihood that it will be executed successfully by the
team
Awake fibreoptic intubation was sometimes not selected as part of the
strategy even when it would seem ideal….
A 115 kg patient with sleep apnoea, limited cervical spine mobility
and tracheal deviation was scheduled for thyroidectomy.
General anaesthesia was induced with remifentanil, propofol and
sevoflurane.
It was not possible to see the vocal cords at direct laryngoscopy
and after repositioning it was not possible to ventilate the patient
either.
Cricothyroidotomy was not possible and the airway was secured by
difficult tracheostomy.
Saturations were < 60% for 20 minutes.
If awake intubation would be ‘best’ but an individual anaesthetist
cannot perform one, should the anaesthetic department have
collective responsibility to provide someone who can?
What is an inhalational induction…?
Does a combination of remifentanil infusion, propofol and a volatile
agent qualify?
What will happen when the airway fails – try a muscle relaxant, wake
up, cricothyrotomy?
In reports it was clear that some patients were neither awake nor
sufficiently anaesthetised and the airway could not be maintained
Is the anaesthetic room always the correct place to start?
The anaesthetic room;
Is usually small or narrow
Difficult to get assistance and surgical
equipment in place
Fairly soundproof
Distant to other members of the team
Poorly lit for surgery
No diathermy
Beds are awkward for surgeons
If surgical help is part of the strategy – start in the operating theatre
Aspiration risk
Not increased in 83 anaesthesia reports
- but in 9 of these patients aspiration was the root cause of poor outcome
Increased in 43 reports;
Intestinal obstruction
8
Reflux
8
Recent ingestion
7
Delayed gastric emptying 7
Pregnancy
4
There was more problem with failing to protect the airway than in trying to
protect it by tracheal intubation
NAP4 Assessment - Good News
Predicted causes of adverse events
Current model (ASA inspired)
• No airway evaluation performed
Assessment of the airway
• Evaluation imperfect in prediction
Preparation for difficulty
• No airway strategy formulated
Strategy at intubation
• Inappropriate strategy
Strategy at extubation
• Best practice strategy fails
Follow-up
• Team unable to complete strategy
• Resources cannot be assembled
All predicted causes of adverse events were seen in NAP4 – there were
no new ones
Therefore our current model of airway management is still valid
Recommendations
All patients should have an airway assessment performed and recorded
The risk of aspiration should be assessed and the adopted strategy
adjusted appropriately
Awake intubation should be used when indicated. Both individuals and
anaesthetic departments should ensure such a service is readily
available
All anaesthetic departments should have an explicit policy for
management of failed or difficult intubation
Individuals should use these strategies in their daily practice