The paediatric airway is for some reason a favourite of the college. Of the twenty-something paediatric SAQs in the last 16 years of the general CICM Part II, seven questions(i.e. around 33%) were about some aspect of airway management. This places the topic of the paediatric airway high on the list of revision priorities for the time-poor exam candidate in advanced stages of cram bloat. This chapter hopefully allows for rapid revision without digressing into useless fluff.
The following past paper SAQs have asked for details about the paediatric airway:
- Question 5 from the second paper of 2014 (generally)
- Question 27 from the first paper of 2016 (stridor)
- Question 9 from the first paper of 2010 (generally)
- Question 4 from the second paper of 2008 (generally)
- Question 9 from the first paper of 2007 (generally)
- Question 11 from the second paper of 2006 (difficult paediatric intubation)
- Question 18 from the first paper of 2005 (generally)
These were all similar enough that basically the same discussion section could be successfully cut-and-pasted across all of them.
The best published references for this topic are probably the belowmentioned articles by Holm-Knudsen et al (2009) and Cardwell et al (2003). Oh's chapter on the topic of airway obstruction (Ch 104, p.1077 of the 7th edition) is also a fun read, but is mainly concerned with discussing the various aetiologies of upper airway obstruction, on which several pages are spent. Relevant management information is literally left until the last half-page, making it an ineffective revision resource.
Unique aspects of paediatric airway management
Broadly, the problems with the paediatric airway can be summarised in a table, which is a good format for answering questions like Question 5 from the second paper of 2014. There, the college wanted not only a list of anatomical features but "strategies that may be used to overcome these", and then complained that "candidates did not read the question thoroughly and did not include strategies in their answer".
Esther Weathers has made available an excellent document in which the pediatric airway caveats are explained, as well as the ways around them. Unfortunately, it is no longer available from www.westernschools.com. Lucky I was able to pillage it before it vanished. This table offered below was put together using the Weathers document, as well as the college answers from all the previous SAQs on this topic.
|And strategies that may be used to overcome these.|
|Anatomical problem||How this is a problem||Strategy to overcome this problem|
|Prominent occiput||Neck is flexed in the supine poistion.
Laryngoscopy will be difficult in this position.
|Small mandible||Less anterior excursion; smaller mouth opening||
|Large tongue||Large tongue relative to the size of the oral cavity. Causes airway obstruction and interferes with laryngoscopy.||
|Larger tonsils and adenoids||Can cause airway obstruction. Nasopharyngeal airways may cause bleeding and aspiration.||
|Superior laryngeal position||Located opposite the C3 to C4 vertebrae, compared with the C4 to C5 in adults. Laryngoscpy is made more difficult.||
|Large, floppy epiglottis||The epiglottis projects further into the airway and covers more of the glottis (until the age of 4)||
|Short trachea||Easy to intubate the right main bronchus.
Easy to inadvertently extubate the child.
|Narrow trachea||More predisposed to obstruction: small decreases in the airway size will cause obstruction.
The needle or surgical cricothyroidotomy is more difficult, as the target is smaller.
One should also be concerned about the risk of tracheal stenosis following prolonged intubation or tracheostomy.
|Soft trachea and cricoid||Cricoid pressure may collapse the airway||
|Anatomic subglottic narrowing||An effective anatomic seal can be expected without the need for a cuffed ETT. Foreign bodies can become lodged below the cords. This resolves by age 10-12.||
The difficult paediatric airway
Question 27 from the first paper of 2016 asked the candidates for "the key management issues" in securing an airway in the case of a child with stridor. The college model answer disappointingly lists "Call for help", "Choice of anaesthetic technique - inhalational versus intravenous" and "Failed intubation drill" which cannot possibly represent a passing level of effort. To expand upon this, I used to main references: Holm-Knudsen et al for "basic aspects" (2009) and Cardwell et al (2003) for "Management of the difficult paediatric airway."
- Call for senior anaesthetic help. The person with the best paediatric airway management expertise should intubate the child.
- Explore alternatives to intubation. In the case of the child with an airway obstruction or stridor, this may consist of the following options:
- Adrenaline nebs
- Steroids (if the aetiology calls for it)
- Optimise pre-intubation management: This consists of adequate pre-oxygenation. It may be necessary for the child to be pre-oxygenated in the parents' lap
- Sit up 90°
- CPAP may help by reducing the dynamic component of stridor
- Atropine can be given (20 µg/kg) to dry secretions
- Explore airway control options:
- Inhalational induction is usually Plan A. The whole point is to maintain spontaneous respiration throughout the process, using gas to attain a level of anaesthesia which permits intubation. Best to induce them in a sitting position. Be prepared to wait- gas induction is slow in airway obstruction. When the patient is ready, they are rapidly made supine and intubated by laryngoscopy.
- IV induction with paralysis is usually Plan B.
- If unable to intubate, proceed to LMA. If LMA ventilation is sucessful, one can prepare for a repeat attempt at intubation, with a variety of difficult intubation equipment avalable, senior staff on standby, and with manoeuvres to improve visibility (eg. improved head position, BURP, videolaryngoscopy)
- If unable to ventilate with LMA, proceed to needle cricothyroidotomy. This is difficult in children. Skileld proceduralists only seem to have a 60% success rate, and puncture the posterior wall of the trachea about 47% of the time.
- If jet oxygenation can be accomplished, one has some time to set up for a Seldinger dilation and insertion of a pediatric ETT, or for a retrgrade intubation.
- If jet ventilation cannot be accomplished, one must assess the difficulty of anterior neck anatomy.
- if the anatomy is easy, one can proceed to a scalpel-bougie tecnique (where one makes an incision in the cricothyroid membrane and railroads the tube in over a hollow jet ventilation bougie)
- if the anatomy is difficult, one must perform a scalpel-needle cricothyroidotomy (where the cricothyroid membrane is identified by palpation through an incision, so that the jet cannula can be inserted)
- Optimise team communication: Ensure all team personnel are aware of the algorithm and understand the steps.
- Optimise first attempt:
- Skilled staff present and briefed about Plan A and Plan B
- Optimise subsequent attempts:
- Checked equipment with backup models
- Senior anaesthetist and ENT surgeon available
- Ensure availability of ultra-fine (~ 2mm) intubating bronchoscope for paediatric work