Time to tighten those sphincters!

aka Pediatric Perplexity 004

A sick two year-old boy has continued to deteriorate in the emergency department. He presented with fever, stridor and a harsh cough.

He now requires intubation for impending airway obstruction.

Questions

Q1. What is the first thing you should do?

Call for help!

Unless you are the Director of Paediatric Anaesthesia at your hospital and have dual training in paediatric ENT surgery…


Q2. What is the probable cause of airway obstruction?

Overall, severe croup is the most likely diagnosis. However, affected patients rarely need intubation if they have received timely medical management.

Other potential causes include:

  • epiglottis (more likely if the child is unimmunised)
  • bacterial tracheitis
  • retropharyngeal abscess
  • foreign body

Q3. Who should perform the intubation?

It depends.

If there is sufficient time to delay intubation, the intubation should be performed by the most expert person available, ideally an experienced pediatric anaesthetist. If there is time, it may be best performed in the operating theatre rather than the emergency department.

If intubation cannot be delayed due to hypoxia or respiratory arrest, then bag-valve mask ventilation with 100% oxygen followed by attempted intubation by the most skilled person immediately available is appropriate. In this case, that’s you.

Q4. Pending intubation, what medical management options can be instituted?

Consider these treatment options:

  • avoid distressing the child!
  • high flow oxygen — if the child is hypoxic the mask may need to be held off the child’s face while he sits in the lap of one of his parents to avoid undue distress (unless the child is too sick).
  • IV steroids e.g. dexamethasone 0.6 mg/kg
  • repeated adrenaline nebulisers
  • heliox (oxygen/ helium mixture) if tolerated

What is heliox?

Heliox is a a mixture of helium and oxygen. Mixtures are available in large compressed gas cylinders and are usually 80%/20% or 70%/30%, which are 1.8 and 1.6 times less dense than pure oxygen, respectively.

Use of heliox substantially reduces the pressures needed to ventilate through small-diameter endotracheal tubes, can give relief to patients with acute upper airway obstruction (less so for those with lower airway obstruction) and can decrease work of breathing. Heliox can be administered via a mask with a reservoir bag.

Q4. What should you have prepared prior to intubation?

The 7 P’s of Preparation

  • plan (A,B, C, etc) — prepare for failure!
  • patient (including consent if applicable)
  • positioning (of the patient)
  • place (modify the environment, should the procedure be done in resus or in theatre?)
  • people (staff, family, bystanders — make sure the right people know what’s going on, that they know there roles, and that everyone else is out of the way)
  • pharmaceuticals (drugs for resuscitation and procedures)
  • procedures (is the equipment ready and available?)

The key equipment required for intubation can be remembered as:

MARBLES

  • monitoring (pulse oximetry, ECG monitoring, end-tidal CO2)
  • airway adjuncts — oropharyngeal and nasopharyngeal airways
  • resuscitation and rapid sequence intubation drugs
  • bag-valve-mask
  • laryngoscopes
  • ETTs of different sizes + introducers/ bougies
  • Suction

Finally, make sure help has been called, that the difficult airway trolley is nearby and that you have a plan B, C, and D — have the equipment needed for needle cricothyroidotomy ready to go.

Ensure that the entire team knows their assigned roles and know the plan.

Q5. What size endotracheal tube would you use? Cuffed or uncuffed?

Some ways of determining the endotracheal tube size include:

  • Modified Cole’s formula: ETT diameter = (age/4) +4
  • use Broselow tape (see video)
  • check that the ETT diameter is the same as the fingernail width of the child’s little (5th) finger.

Make sure you have a range of ETT sizes available, in case your first option doesn’t fit.

Cuffed or uncuffed?

This seems to be an endless debate. Cuffed tubes historically have a bad rep. However, modern cuffed tubes have high volume-low pressure cuffs that make subglottic stenosis less of a concern.

Khine et al (1997) performed a randomised study of 488 children less than age 8 years undergoing general anaesthesia and found that cuffed endotracheal tubes had advantages: avoidance of repeated laryngoscopy, use of low fresh gas flow, and reduction of the concentration of anesthetics detectable in the operating room. The Khine formula for ETT size was (age/4) +3.

More recently, Weiss et al (2009), in a randomised study of over 2000 children <5 years old, found that the use of cuffed tubes in small children provided a reliably sealed airway at cuff pressures of 20 cm H2O or less, reduced the need for tube exchanges, and did not increase the risk for post-extubation stridor compared with uncuffed tubes.

My preferred approach is to use a cuffed tube if available, usually a size or a half-size smaller than I would otherwise use (e.g. the Khine formula). If the tube is slightly small, the leak can be overcome by inflating the cuff until the leak just disappears.  An excessive leak around the tube can make oxygenation and ventilation difficult in children with significant lung disease. The cuff should be periodically deflated to ensure a leak is still detectable (or cuff pressures checked — should be <25 cmH2O), as local swelling may decrease the required cuff volume.

Q7. What are your options for induction of anaesthesia prior to emergency intubation of this child?

Awake fiber-optic intubation would be nice, but isn’t realistic in a distressed 2 year-old with acute airway obstruction.

You are left with two choices:

  • inhalational induction with maintenance of spontaneous ventilation
  • rapid sequence intubation with IV induction and paralysis

Q8. How would you perform an inhalational induction?

Technique:

  • this requires experience in inhalational induction techniques
  • apply mask with high flow oxygen
  • introduce volatile anesthetic (e.g. sevoflurane)
  • Allow spontaneous ventilation during induction
  • Once sufficient depth of anesthesia is achieved intubation can be attempted, or once the ability to ventilate is confirmed, a neuromuscular blocking agent may be administered
  • IV access may be obtained following induction — be prepared to give IM suxamethonium 4-6mg/kg for laryngospasm, or IM atropine 0.02mg/kg for bradycardia if IV access is not available. Consider the intraosseous route if IV access is difficult.

Why use sevoflurane?

Sevoflurane has relatively less cardiovascular depression, bradycardia and dysrhythmias than, say, halothane (which sensitises the heart to catecholamines – which may be a problem in this situation). Sevoflurane is less likely to cause airway irritation, breath-holding or laryngospasm than other inhaled anesthetics, and it causes less respiratory depression. Also, it doesn’t cause renal toxicity from inorganic fluoride production.

Q9. How would you perform intravenous induction?

Technique:

  • IV access is required — this may distress the child and worsen hypoxia; IM ketamine and IM suxamethonium are alternatives
  • apply mask with high flow oxygen
  • administer a rapid acting induction agent (e.g. thiopentone, ketamine)
  • administer a neuromuscular blocking agent to achieve paralysis (e.g. suxamethonium, rocuronium) — this carries the risk of not being able to ventilate the paralysed patient.
  • attempt intubation

Q10. What are your options if you are unable to intubate the child?

Attempt ventilation using bag-valve-mask +/- airway adjuncts or a laryngeal mask (LMA) until assistance is available. Consider adjusting patient position and  intubation technique (e.g. change laryngoscope blade, change use of cricoid pressure/ BURP, change ETT size, use bougie/ stylet) prior to reattempting.

If unable to ventilate and the cavalry haven’t appeared yet, then percutaneous needle cricothyroidotomy will be required.

Lucky you prepared for this and called the ENT surgeon before attempting intubation, eh!

References

  • Khine HH, Corddry DH, Kettrick RG, et al. Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology 1997;86:627-631. PMID: 9066329
  • Marx JA, Hockberger R, Walls RM. Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th edition (2009) Mosby, Inc. [mdconsult.com]
  • McGarvey JM, Pollack CV. Heliox in airway management. Emerg Med Clin North Am. 2008 Nov;26(4):905-20, viii. Review. PMID: 19059090.
  • Walls RM, Murphy MF. Manual of Emergency Airway Management, 3rd Edition (2008) Lippincott Williams & Wilkins.
  • Weiss M, Dullenkopf A, Fischer JE, Keller C, Gerber AC; European Paediatric Endotracheal Intubation Study Group. Prospective randomized controlled multi-centre trial of cuffed or uncuffed endotracheal tubes in small children. Br J Anaesth. 2009 Dec;103(6):867-73. Epub 2009 Nov 3. PubMed PMID: 19887533.

[A similar scenario was in the JFICM April/May 2007 Fellowship examination]

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Comments

  1. says

    Thanks for that Chris
    Just what I wanted to know.
    What is the role of nebulised adrenaline -- can it create a window of “intubation wonder” where the larynx is less oedematous, the kid has good inotropy and respiratory drive going.

    My question is: Should we try one more neb just prior to any intubation, as long as it doesn’t distress the kid too much?
    Casey

Comments