Emergency airway management
Securing a child’s airway in an emergency setting can be challenging, and success here is dictated by a mosaic of factors such as clinician experience, appropriate instrumentation, and, importantly, the many anatomical and physiological considerations that differ significantly from the adult population.
Securing a child’s airway in an emergency setting can be challenging, and success here is dictated by a mosaic of factors such as clinician experience, appropriate instrumentation, and, importantly, the many anatomical and physiological considerations that differ significantly from the adult population. Airway management is one of the most important skills a pediatric emergency physician can have and, therefore, clinicians should have an in-depth understanding of the anatomical and physiological differences in children, and be acutely aware and vigilant of the pitfalls associated with emergency airway management in these patients.
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Endotracheal intubation is the standard for securing the airway in patients and remains the optimal airway management technique for providing better oxygenation and ventilation while at the same time avoiding gastric insufflation and protecting against aspiration. Nevertheless, success rates in children are lower than in adults, begging the need for improved efforts in correcting the lag.1,2
Pediatric vs adult airway
The anatomical differences in the normal pediatric airway compared with the adult airway are significant (Figure3), and these are more evident in children aged younger than 2 to 3 years.4 These differences, including a prominent occiput, large tongue, larger tonsils and adenoids, and a superior laryngeal position, are among some of the reasons why laryngoscopy and endotracheal intubation can prove challenging in the pediatric patient population.2-5
The head of a child is larger relative to his/her body size, with a prominent occiput. This causes varying degrees of neck flexion and airway buckling in the supine position, possibly leading to anatomic airway obstruction in sleeping children, as well as interference in visualizing the glottis opening during laryngoscopy.6 A larger occiput, in combination with a shorter neck, makes laryngoscopy even more challenging, as it provides obstacles to the alignment of the oral, laryngeal, and tracheal axes. In contrast to placing a pad under the occiput of adults, placing a towel roll under the shoulders of the pediatric patient can suffice in achieving a neutral position of the neck, facilitating an optimal view of the glottis as well as ideal airway alignment in the patient.2-6
Further impeding proper visualization of the deeper airway during direct laryngoscopy is a large tongue. Infants and young children have relatively large tongues that fill a greater portion of the oral cavity, and a large tongue is the most common cause of upper airway obstruction in children, particularly in patients with depressed mental status and concomitant loss of intrinsic airway tone. It is important to remember that in contrast to adults in whom the overwhelming majority of intrinsic airway obstruction occurs at the level of the soft palate, approximately half of obstructions in infants are retroglossal obstructions.2-6
In young children, prominent adenoids and tonsils are also frequently found, often leading to elective ears-nose-throat (ENT) surgery. This increased mass of lymphoid tissue has been shown to contribute to airway obstruction in children. In addition, adenoidal bleeding can occur following the placement of a nasopharyngeal airway or nasotracheal intubation. In this scenario, the resultant blood in the nasopharynx and hypopharynx can lead to aspiration and render glottis visualization challenging. All these factors can contribute to the loss of upper airway space, which can further lead to difficulties with mask ventilation and obstruction during spontaneous ventilation, making laryngoscopy more challenging.2,4
Compared with adults, the larynx in infants and children is positioned relatively higher in the neck, assuming a more cephalad position. The cricoid ring is located approximately at the level of the C4 vertebrae at birth, C5 at age 6 years, and C6 as adult, and angled more anteriorinferior to posterior-superior. The vocal cords are not typically found at a right angle (90°) to the trachea.5 Although these factors do not affect laryngoscopic view, they can make the insertion of the endotracheal tube more challenging or more traumatic.
NEXT: Age-specific differences
The epiglottis is often large and floppy in children, particularly in those aged younger than 3 years.2-6 Angled more acutely with respect to the axis of the trachea, the pediatric epiglottis projects into the airway and covers more of the glottic aperture. These factors can further hinder passing an endotracheal tube.
Other anatomic considerations in the pediatric population that can complicate and make airway management challenging include a weaker hypoepiglottic ligament, anatomic subglottic narrowing, a shorter or narrow trachea, and a compliant chest wall.2
Age-specific differences
There are several age-specific physiological features and challenges in pediatric patients that clinicians must consider in emergency airway management, all of which can predispose the patient to hypoxemia. These include a higher oxygen metabolism; lower functional residual capacity; age-related respiratory rate; preferential nasal breathing; smaller tidal volumes; tendency to respiratory fatigue; and higher vagal tone.2,5
Younger children have higher basal oxygen consumption rates (twice that of adults: 6 mL/kg/min versus 3 mL/kg/min, respectively), and their functional residual capacity is proportionally smaller. Compared with adults, this higher oxygen consumption, coupled with the lower functional residual capacity in children, can lead to rapid desaturation during apnea, such as during laryngoscopy or rapid sequence induction, despite robust efforts in preoxygenation. In healthy children aged younger than 6 months, the mean time to desaturation to 90% following preoxygenation is approximately 90 seconds compared with 6 minutes in adolescents and adults.7
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Vital signs are age dependent and should be interpreted as appropriate to the age of the child. Clinicians need to be able to discriminate between normal and concerning vital sign values and trends when evaluating the pediatric patient for respiratory illness as well as response to therapy.5
Infants are obligate nasal breathers, and for the majority the nares account for approximately half the total airway resistance. Here, extra caution should be taken, as obstruction by secretions, edema, or compression from nonflowing nasal cannula or a misplaced face mask can lead to significant increase in breathing labor. Infants and young children also have small physiologic tidal volumes relative to their body size (6 mL/kg-8 mL/kg) and as a result, they are easily prone to iatrogenic barotrauma following aggressive positive pressure ventilation.2,5
The resistance to flow in the airway is governed by Poiseuille’s law, which states that airflow resistance is proportional to the fourth power of the airway radius (the smaller airways with the same degree of airway edema result in proportionately greater obstruction). There are several different disease processes that could result in a narrowing of the airway and severely impede respiratory function including growths within the airway, such as tracheomalacia, laryngomalacia, and laryngeal clefts; iatrogenic causes such as vocal cord paralysis and subglottic stenosis; or compression of the airway structures by a mass located outside the airway.8
In addition, infants and young children are more prone to bradycardia and laryngospasm with laryngeal stimulation, which can further complicate endotracheal intubation. Because hypoxia potentiates the risk for bradycardia, clinicians should try to maximize and maintain oxygenation before and during the intubation procedure.5
NEXT: Practice makes perfect
Practice makes perfect
Management of the infant and pediatric airway can pose unique challenges. Beyond having a requisite in-depth knowledge of the anatomical and physiological considerations in the pediatric patient, clinicians also need to have enough practice in laryngoscopy and endotracheal intubation in order to achieve and maintain technique proficiency. This can be challenging, however, because of the relative infrequency with which most practitioners perform such procedures.2
In one past study9 in which researchers investigated the first-time success rates for 114 pediatric rapid-sequence intubations performed in children’s hospital emergency departments, it was found that pediatric emergency-medicine attending physicians had a higher first-time success rate (89%) than pediatric emergency fellows (43%) or pediatric residents (35%). After adjusting for patient characteristics and illness severity, attending physicians were 10 times more likely to be successful on the first attempt than all the trainees combined. These results highlight the importance of achieving proficiency in emergency airway management techniques.
Another study found that simulation training can provide an alternative means for pediatric airway management training.10 Simulation training is one approach that could improve competency and maintain proficiency in airway management techniques in less-experienced clinicians.
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One has to be cautious to choose age-appropriate equipment for the individual patient.5 One size does not fit all, and choosing the appropriately sized equipment for the patient is of paramount importance and helps contribute toward positive outcomes in emergency airway management.
REFERENCES
1. Divatia JV, Bhowmick K. Complications of endotracheal intubation and other airway management procedures. Indian J Anaesth. 2005;49(4):308-318.
2. Nagler J. Emergency airway management in children: unique pediatric considerations. UpToDate. http://www.uptodate.com/contents/emergency-airway-management-in-children-unique-pediatric-considerations. Updated June 6, 2016. Accessed April 20, 2017.
3. Coté CJ, Lerman J, Anderson BJ. A Practice of Anesthesia for Infants and Children.. 5th ed. Philadelphia, PA: Saunders/Elsevier; 2013:chap 12.
4. Mick NW. The difficult pediatric airway. UpToDate. Available at: http://www.uptodate.com/contents/the-difficult-pediatric-airway. Updated April 20, 2016. Accessed April 20, 2017.
5. Coté CJ. The difficult paediatric airway. South Afr J Anaesth Analg. 2012;18(5):230-239.
6. Nagler J, Bachur RG. Advanced airway management. Curr Opin Pediatr. 2009;21(3):299-305.
7. Patel R, Lenczyk M, Hannallah RS, McGill WA. Age and the onset of desaturation in apnoeic children. Can J Anaesth. 1994;41(9):771-774.
8. Bruce IA, Rothera MP. Upper airway obstruction in children. Paediatr Anaesth. 2009;19 suppl 1:88-99.
9. Kerrey BT, Rinderknecht AS, Geis GL, Nigrovic LE, Mittiga MR. Rapid sequence intubation for pediatric emergency patients: higher frequency of failed attempts and adverse effects found by video review. Ann Emerg Med. 2012;60(3):251-259.
10. Kennedy CC, Cannon EK, Warner DO, Cook DA. Advanced airway management simulation training in medical education: a systematic review and meta-analysis. Crit Care Med. 2014;42(1):169-178.
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