3. Flashcards
a) Which nerves supply sensation to i) the nasal air passages (10%), ii) the oropharynx (10%) iii) the
larynx? (10%
Nasal air passages = ophthalmic and maxillary divisions of facial nerve:
> Anterior septum and nares: anterior ethmoidal nerve (V1).
> Elsewhere: greater and lesser palatine nerves (V2).
Oropharynx = glossopharyngeal nerve.
Larynx = vagus:
> Above vocal folds: internal laryngeal branch of superior laryngeal nerve.
> Below vocal folds: recurrent laryngeal nerve.
b) Outline the techniques for achieving local anaesthesia of these areas? (15%)
> Spray as you go. Co-phenylcaine mucosal atomisation device to nostrils,
1% lignocaine spray to tongue and oropharynx, 2% lignocaine via
epidural catheter to larynx above and below the cords.
Topicalisation with local anaesthetic soaked pledgets in nasal passages
(disadvantages: does not reduce sensation of any other area).
Nebulised local anaesthetic (disadvantages: easy to exceed maximum
local anaesthetic doses, does not work for larynx, requires the patient
to take good breaths, which is often not possible in patients requiring
awake intubation).
Individual nerve blocks: glossopharyngeal nerve, superior laryngeal
nerve block, recurrent laryngeal nerve block etc. (disadvantages: patient
discomfort, especially in a patient who already has airway compromise;
multiple blocks needed; and expertise in unusually performed blocks
required).
Cricothyroid puncture for translaryngeal block (disadvantages:
anaesthetises larynx only, patient discomfort).
c) What are the indications (15%) and contraindications (15%) for awake fibreoptic intubation?
Indications:
> Previous difficult airway for intubation or face mask ventilation.
> Predicted difficult airway:
• Dentition.
• Limited mouth opening (facial fractures, rheumatoid arthritis, dental
abscess, scleroderma).
• Limited neck movement (rheumatoid arthritis, ankylosing spondylitis,
previous cervical spine surgery or trauma)
• Airway anatomy abnormality (thyroid, tongue, tonsillar or laryngeal
tumours, epiglottitis, Ludwig’s angina, airway oedema or burns,
obesity, retrognathia, previous neck radiotherapy).
• Syndromes associated with difficult airway (Pierre-Robin,
Treacher-Collins).
> Need for intubation but requirement to stay awake, e.g. need for
neurological examination following intubation.
Contraindications:
> Patient refusal.
> Patient not able to comply (confusion, young age etc.).
> Local anaesthetic allergy.
> Operator inexperience.
> Subglottic airway issue (i.e. if the predicted difficulty in the airway is below
the glottis, it won’t be overcome by fibreoptic intubation).
> Significant laryngeal stenosis.
> Threat of airway obstruction.
> Airway bleeding or risk of airway bleeding due to e.g. vascular tumour
d) List the complications of awake fibreoptic intubation. (25%)
Drugs related:
> Failure to achieve adequate anaesthesia of airway resulting in patient
discomfort.
> Local anaesthetic toxicity.
> Nerve damage secondary to nerve blocks if used.
> Apnoea, loss of consciousness and loss of airway due to sedation,
if used.
Airway related:
> Trauma to any of the structures en route.
> Airway obstruction due to fibreoptic scope and tube, airway oedema,
bleeding, laryngospasm.
> Failure to achieve secure airway due to operator inexperience, patient
noncompliance, airway more problematic than anticipated.
> Aspiration of blood from trauma of procedure or pre-existing bleeding,
or secondary to full stomach. Consequent risk of lower respiratory tract
infection etc.
> Bronchospasm.
a) What airway, respiratory and
cardiovascular problems may
follow the removal of a tracheal
tube? (50%)
Airway:
> Sore throat, hoarseness.
> Foreign body causing obstruction: teeth, throat pack, blood clot.
> External compression of airway due to surgical site swelling/bleeding.
> Laryngospasm: triggered by blood, secretions and airway manipulation
during light anaesthesia.
> Laryngeal oedema.
> Laryngeal trauma caused during intubation (e.g. bougie use), causing
bleeding, swelling, tears.
> Vocal cord paralysis: direct trauma/pressure.
> Vocal cord dysfunction.
> Tracheomalacia: erosion/softening of tracheal rings due to prolonged
intubation, retrosternal thyroid, large thymus or tumour.
> Tracheal stenosis after prolonged intubation.
Respiratory:
> Coughing.
> Mucociliary dysfunction.
> Diffusion hypoxia.
> Basal atelectasis causing ventilation/perfusion mismatch.
> Inadequate minute ventilation due to ongoing sedation.
> Post-obstructive pulmonary oedema.
> Bronchospasm.
> Pulmonary aspiration.
> Respiratory failure due to any respiratory or airway complications.
Cardiovascular:
> Catecholamine release causing tachycardia and hypertension.
> This may result in reduced ejection fraction in patients with coronary
artery disease.
> Risk of silent or overt myocardial infarction due to increased myocardial
oxygen demand (effect exacerbated if there is hypoxaemia due to other
complications of extubation).
b) List the patient and surgical
factors that may contribute to a
high-risk extubation. (30%)
Patient factors:
> Airway: dysmorphia, musculoskeletal disease contributing to airway
difficulties (rheumatoid arthritis, ankylosis), airway pathology (tumour),
obesity. These issues may have been detected at preoperative
assessment or at intubation: difficult airway assessment, difficult face
mask ventilation, difficult intubation, complications at intubation.
> Breathing: respiratory disease including asthma, obstructive sleep
apnoea, chronic obstructive pulmonary disease, recent upper respiratory
tract infection (especially in children), smoking.
> Cardiovascular: ischaemic heart disease, unstable arrhythmias.
> Neurological: posterior fossa tumour, head injury, Guillain–Barré,
myasthenia gravis, multiple sclerosis.
> Gastrointestinal: full stomach, reflux, hiatus hernia.
> Muscular: muscular dystrophy, dystrophia myotonica.
Surgical factors:
> Site: airway, head, neck, thorax, posterior fossa, cervical spine. Any
surgery requiring use of double-lumen tube.
> Complications of surgery or double-lumen tube use: bleeding, swelling,
infection.
> Duration: prolonged intubation predictive of problems with extubation.
> Position: Trendelenberg exacerbates development of laryngeal oedema.
> Intraoperative issues not directly related to airway: difficulty achieving
adequate ventilation, hypothermia, significant blood loss, electrolyte
imbalance, fluid shifts.
c) Outline the strategies used to
prevent airway complications if a
difficult extubation is anticipated
in the operating theatre. (20%)
Extubate in theatre:
> Pre-medicate with proton pump inhibitor if appropriate.
> Plan A, plan B, plan C.
> Involve colleagues with specific airway skills +/− ENT.
> Ensure full difficult airway kit to hand.
> Ensure cardiovascular, respiratory and metabolic stability.
> Optimise oxygenation prior to starting, ongoing full monitoring.
> Ensure full reversal of neuromuscular blockade.
> Position: left lateral head down or sitting up.
> Extubation wide awake: good grip, tongue protrusion, adequate minute
ventilation.
Consideration of additional techniques:
> Exchange of tube for SAD when deep +/− still paralysed.
> Use of airway exchange catheter.
> Use of nasopharyngeal or oropharyngeal airway.
> Flexible bronchoscope through the LMA to visualise the larynx and vocal
cords to check for cord paralysis and tracheomalacia (if indicated due to
type of surgery).
> Extubation onto noninvasive ventilation or high-flow humidified oxygen.
> Use of remifentanil to manage awake extubation.
Delayed extubation if reversible contributing factors:
> Transfer to ICU with a plan for delayed extubation.
> Avoid positive fluid balance.
> Ensure normothermia.
> Normalise electrolytes.
> Allow any airway swelling to settle; consider need for steroid therapy.
Surgical tracheostomy if contributing
factors are not readily reversible:
> Nature of surgery: flaps, spinal fixation, complications from airway
tumour.
