The Pediatric Airway: Pearls and Pitfalls

Authors: Michael Oh, MD and Muhammad Waseem, MD (Emergency Medicine, Lincoln Medical & Mental Health Center) // Edited by: Alex Koyfman, MD (@EMHighAK) and Brit Long, MD (@long_brit, EM Chief Resident at SAUSHEC, USAF)

Airway management is one of the most important skills in the evaluation of a child in distress. In a critically ill child, the evaluation begins with establishing a patent airway. Children are not small adults, and there are many anatomical and physiological differences, as well as a myriad of etiologies precipitating the event that may necessitate immediate airway management. Knowledge of these differences allows the emergency physician to formulate and execute safe and effective management of the pediatric airway. One should always anticipate respiratory failure because of limited respiratory compensatory capacity in children. Anticipate respiratory failure if there is an increased respiratory rate with signs of distress (such as increased effort, nasal flaring, retractions, or grunting) or an inadequate respiratory rate, effort, or chest excursion.

 

Age Appropriate Equipment

One cannot over-emphasize the importance of the appropriate equipment size for children. One size does not fit all. The pediatric age group represents a spectrum from neonates to infants, children, and adolescents. Each child is different and requires an individualized selection of equipment. Choosing correctly sized airway equipment makes a difference. If not carefully selected, even a small error in the selection of a face mask may result in air leak and inadequate ventilation. The fundamental procedure in airway management is properly performed mask ventilation. In an unconscious child, select the size appropriate to the oropharyngeal airway. If it is too small, it will not keep the tongue from obstructing the pharynx, and if it is too large, it may obstruct the airway.

 

Cuffed vs Un-cuffed Endotracheal Tubes

Controversy still remains as to whether to use a cuffed or un-cuffed endotracheal tube in children under 8 years of age. For many years, un-cuffed tubes have been used in children of this age. The un-cuffed tube is positioned to form a seal at the cricoid ring, which is the narrowest portion of the child’s airway, whereas the glottis is the narrowest portion in the adult airway. The airway in children is funnel-shaped with an anatomical narrowing below the vocal cords. Concern about pressure-related subglottic injury from the use of cuffed endotracheal tubes in young children has resulted in mixed recommendations. However, with adequate attention to cuff pressures, cuffed tubes can provide ventilation without significant additional risk. Beyond the newborn period, many practitioners accept cuffed tubes in children one year and older.

 

What is the best body position?

The relatively larger head and tongue and more anterior airway of the child require proper alignment of the oropharyngeal and tracheal axes. The large tongue is the most common cause of airway obstruction in children. In the supine position, the large head puts the neck into flexion. An optimal view of the glottis may be facilitated with the use of a rolled up bed-sheet placed under the child’s back and shoulders in order to extend the neck and align the axes.

 

Miller (Straight) vs Macintosh (Curved) Blade: which one should I choose?

Selection of a laryngoscope blade type: Personal preference.

Both have shown comparable success for intubation, leaving the option up to the preference of the provider performing the intubation procedure.

Miller Blade: Since the pediatric larynx is located more superiorly and the epiglottis is longer and potentially floppier, the miller blade is potentially more appropriate to visualize the epiglottis.  Placing the tip of the Miller blade in the vallecula may provide a more satisfactory view.

Macintosh Blade: Although many anesthesiologists prefer the Miller blade, due to the aforementioned anatomical differences, both blades offer similar success rates in providing an adequate view of the glottis.

 

Physiologic Considerations

– Greater airway resistance: Poiseuille’s equation states that airflow resistance is proportional to the fourth power of the radius (smaller airways with the same degree of airway edema result in proportionately greater obstruction).

– Higher metabolic rate, increased oxygen consumption, and rapid desaturation.

– Infants are obligate nasal breathers: dependent on nasopharynx patency therefore nasal airway should be avoided in infants.

– Smaller functional residual capacity than adults (faster desaturation).

– Minimize bag valve mask ventilation (prevent gastric insufflation).

– Vital signs are age-dependent and should be interpreted as appropriate to the age of the child.

– Physiologic tidal volume is 6-8 ml/kg. However, considering the dead space of the bag-mask device, 10 ml/kg is sufficient for effective chest rise.

– Ventilation rate: Infant 20-30 breaths/minute; older children 16-20 breaths/minute.

 

RSI Medications

In children medications exhibit effects more rapidly at onset and of a shorter duration, in part due to the larger extracellular fluid compartment. Dosages are weight-dependent, and in the acute setting, color-coded resuscitation tapes are useful.

Atropine has the potential to reduce oral secretions and risk for laryngoscopy-induced bradycardia, particularly in neonates. However, close examination of the literature does not support this, and many argue that atropine is no longer needed or beneficial.

Lidocaine potentially blunts the rise in intracranial pressure during laryngoscopy, though this is controversial. Fentanyl given before intubation may be a better option.

 

Color-Coded Tape

Length-based resuscitation tapes are helpful for children up to approximately 36 kg. Each color- coded zone is paired with particular resuscitation equipment and medications appropriate to the patient’s body weight. The colors on the tape are aligned with drawers on a pediatric resuscitation cart. Controversy exists whether these methods may underestimate the medication dosage, especially for obese children.

 

Numbers/calculations:

For un-cuffed tube (mm ID): Age +16/4 or Age/4 + 4

For cuffed tube (mm ID): (Age in years/4) + 3

Note: Endotracheal tube size is more reliably estimated when based on a child’s body length.

Rough estimation ET Tube Size: Size of that child’s little finger.

Depth of ET tube = Tube size x 3

Rough estimation of Nasogastric & Orogastric tube size = 2 X endotracheal tube size

Maximum suction = 80 -120 mm Hg (via an endotracheal tube)

 

Importance of Verification of Correct Tube Placement

Children are at high risk of endotracheal tube misplacement or obstruction. Therefore, endotracheal tube placement should be confirmed by more than one method; one of these methods should include a carbon dioxide detection device.

Yellow = yes and Purple = problem

An ETCO2 Monitor quantifies the ETCO: i.e. a typical square waveform reliably confirms tracheal intubation.

 

Video Laryngoscopy vs. Direct Laryngoscopy

Glidescopy allows a view of the glottis without aligning oral, laryngeal, and tracheal axes and may provide a better view of the glottis. However, the use of a glidescope may require a longer time to achieve intubation.

 

Laryngeal Mask Airway

Insufficient evidence exists to recommend for or against its routine use.

Acceptable adjunct only for experienced providers in the “cannot intubate, cannot ventilate situation” BUT it is not a definitive airway.

Works only in the case of normal anatomy.

Disadvantages:

  • There is a lack of airway protection from vomiting or aspiration of gastric contents.
  • There is the requirement that the patient be unconscious or sedated for placement.
  • There is an increased risk of dislodgement in young children.

For children < 30 kg: A higher ventilation pressure may be required, since it can fold the epiglottis over and cause partial upper airway obstruction.

 

Difficult Pediatric Airway

Needle Cricothyrotomy/Percutaneous Trans-tracheal Jet Ventilation (PTJV)

Although the surgical airway procedure would be the method of choice, in patients 12 years or less in whom the surgical airway is technically difficult to perform, jet ventilation provides oxygenation. This is not a definitive airway; can be oxygenated, but ventilation is limited

Open Cricothyrotomy is not recommended because, in children the cricothyroid membrane surface area is too small.

 

Conclusion

The pediatric airway is more challenging than the adult airway:

  1. Position the child with the aid of rolled bed-sheets in order to align the oropharyngeal and tracheal axes.
  2. Both the Miller and Macintosh Blades are acceptable. Use what you are comfortable with.
  3. Although, un-cuffed endotracheal tubes are generally used in children under 8 years of age, cuffed tubes may be used in children 1 year and older, but probably should not be used in neonates.
  4. Recognize that children have both anatomic and physiologic differences relative to adults.
  5. For a difficult pediatric airway, consider jet insufflation.

 

References / Further Reading

  1. Perkin RM, Van Stralen D. Pediatric passages. 10 pitfalls to avoid in pediatric airway management. JEMS. 2000 Mar;25(3):50-64
  2. Santillanes G, Gausche-Hill M. Pediatric airway management. Emerg Med Clin North Am. 2008 Nov;26(4):961-75
  3. Sun Y,Lu YHuang YJiang H. Paediatr Anaesth. Pediatric video laryngoscope versus direct laryngoscope: a meta-analysis of randomized controlled trials. 2014 Oct;24(10):1056-65
  4. Fiadjoe J, Stricker P. Pediatric difficult airway management: current devices and techniques. Anesthesiol Clin. 2009 Jun;27(2):185-95
  5. Walker RW, Ellwood J. Themanagement of difficult intubation in children. Paediatr Anaesth. 2009 Jul;19 Suppl 1:77-87
  6. http://www.ncbi.nlm.nih.gov/pubmed/25441044