Anatomically, the airway is ever changing in size, anteroposterior alignment, and point of most narrow dimension. Special considerations regarding obesity, chronic and acute illness, underlying developmental abnormalities, and age can all affect preparation and intervention toward securing a definitive airway. Mechanical ventilation strategies should focus on limiting peak inspiratory pressures and optimizing lung protective tidal volumes. Emergency physicians should work toward minimizing risk of peri-intubation hypoxemia and arrest. With review of anatomic and physiologic principles in the setting of a practical approach toward evaluating and managing distress and failure, emergency physicians can successfully manage critical pediatric airway encounters.
Key points
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The pediatric airway is more anterior and superior, with the subglottic region being most narrow, and these differences are pronounced until at least age 8 years, when proportions begin to resemble more closely those of adults.
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Video laryngoscopy has become a common and successful technique used in several airway management scenarios owing to improved glottic views and ease of training.
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Noninvasive ventilation, including continuous positive airway pressure, bilevel positive airway pressure, and high-flow nasal canula, is highly effective in treating pediatric respiratory failure but does not replace intubation if needed.
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When properly adjusted for size, cuffed tracheal tubes are safe to use with pediatric airways, except in neonates, with fewer air leaks during assisted ventilation and less postextubation stridor than uncuffed tubes.
Introduction
Emergency physicians are highly trained in the management of threatened, injured, or compromised airways. The expectation of emergency physicians is to successfully complete this task, no matter the age or condition of the patient. In special circumstances, assistance from anesthesia, otolaryngology, or other surgical specialty may be called on if available, which may facilitate securing the airway but does not guarantee success. Few airway emergencies are as emotionally charged as a crashing pediatric patient. The most common overall complication of managing a pediatric airway is transient hypoxemia (<85%), with the most serious complication of failed airway management being cardiac arrest. This article provides current emergency physicians with tips, tricks, and strategies to more confidently enter the next pediatric resuscitation and achieve the desired outcome. Moving forward, it is important to remember that the pediatric airway is different, not alien, and can be challenging, but is not impossible.
Anatomic considerations
The first, most glaring difference of the pediatric airway from that of the adult is size. This size range can create anxiety given the margin of error in technique is also smaller when intubating. The range of equipment sizes is larger and requires more forethought as well. The larger omega-shaped epiglottis is longer, floppier, and more prone to obscuring the view of the glottic opening. This difference in particular highlights the benefit of using a straight laryngoscope blade, which can lift the epiglottis from view and allow more direct visualization of the pediatric glottis when anatomic axes are appropriately aligned. A list of available straight blades can be found in Box 1 . Curved blades, which can also be used to optimize glottic views, can be found in Box 2 . Other types of laryngoscope blades are listed in Box 3 .
Blade name:
Cranwall
Jackson
Janeway
Magill
Miller
Phillips
Robertshaw
Seward
Soper
Wis-Hipple
Wisconsin
Blade name:
Macintosh
Reduced Flange Macintosh
Parrott
Siker
Blade name:
McCoy
Vie Scope
In the neonatal period, laryngeal structures are the most superior, aligned near the second cervical vertebral body (C2). By adolescence, the larynx has dropped to near the C5-C6 level. This change means that the angle from the base of the tongue to the glottic opening is most acute with the youngest patients. The infant airway also has a lower-lying posterior palate, and, with the proportionally larger epiglottis, the nasopharynx and hypopharynx are in closer proximity, which encourages obligate nasal breathing that decreases risk of aspiration. These features, in addition to a more anterior airway and smaller glottic opening, can increase the challenge of proper alignment of anatomic axes and optimal intubating positioning.
The next significant difference is the location of the narrowest point of the airway. In a normal adult, the glottic opening is the narrowest, such that, once the tracheal tube has been passed through the vocal cords, there should be no other restriction to placement. However, in children up to 8 years of age, the subglottic area has the most narrow dimensions, at the level of the cricoid. This narrowing can be even more exaggerated in children with history of laryngotracheomalacia or tracheomalacia ( Fig. 1 ).
Pediatric airway cross-sectional area shows no significant difference with respect to sex until after 14 years of age. After that time, the airways of male patients are approximately 25% larger with respect to cross-sectional area. This difference is likely caused by pubertal development and growth spurts.
Obesity and Airway
Obesity has been shown to have negative predictive value of airway size in adults, thought to be caused by physical compressive forces, as well as the effects of thoracic pressure. Similar findings have not yet been established in pediatrics; however, a retrospective case series of computed tomography and MRI of the neck of 171 pediatric patients at a tertiary care center showed a similar notable trend of smaller airway size with higher body mass index. This trend did not meet statistical significance but may inform future research and provide an additional consideration to airway management, such that having the next-smaller tube size available is an important option at time of intubation.
Differences in physiology
Infants and children have higher diaphragms with proportionally larger abdominal contents causing reduced lung volumes. Developing alveoli, smaller thoraces, and differences in tissue recoil are causes for a lower functional residual capacity (FRC) in infants and children. Because FRC is the gas still in lungs at the end of normal tidal expiration, it is also responsible for gas exchange. The smaller FRC in combination with children’s higher metabolic rates and oxygen demand shortens the window during which intubation can be performed with optimized oxygenation. Oxygen demand is estimated at twice that of adults, and highlights the rationale for performing apneic oxygenation during intubation. Data on apneic oxygenation for pediatric patients undergoing emergent intubation in the pediatric emergency department are slightly mixed; however, 2 recent studies, Vukovic and colleagues and Overmann and colleagues, used alternative methods, which likely account for the opposing findings. Results supporting use of apneic oxygenation from Vukovic and colleagues in 2018 used standard nasal canula, 4 L/min for patients up to 2 years of age, 6 L/min between 2 and 12 years old, and 8 L/min for those greater than 12 years old.
Approach to acute respiratory failure in pediatrics
Respiratory failure can be caused by a variety of parenchymal diseases or injury, impending or acute airway obstruction, metabolic demand that exceeds that of the patient’s respiratory function, and neurologic compromise such that the airway itself cannot be self-protected. The underlying cause of the patient’s respiratory failure can and should direct the approach to ventilatory support and supplemental oxygenation. For example, for those patients with parenchymal disease, hypoxemia may be caused by alveolar inflammation and fluid accumulation; therefore, it may be appropriate to start with noninvasive ventilation (NIV) before proceeding to intubation. For children with severe thermal airway injury or acute epiglottitis, placing a tracheal tube is an emergent procedure to prevent impending airway closure; noninvasive measures are likely to be inadequate. Emergency physicians must also take a measured approach in deciding the most appropriate airway interventions with respect to transfer to definitive disposition, especially if such disposition requires transport via ambulance or helicopter.
When resuscitation and support measures are underway, it is important to keep parents and caregivers updated on the indications and plan for management. In addition to consent, they can provide the much-needed emotional support, assist in calming the child during anxiety-provoking procedures, and aid in redirection from attempts at removing support lines and devices, such as high-flow nasal canula (HFNC) and continuous positive airway pressure (CPAP).
Noninvasive ventilatory support and high-flow nasal canula
The benefits of NIV are numerous for both adults and children. Specifically, NIV supports patency of the upper airway, increases FRC, reverses hypoventilation, decreases work of breathing, and decreases oxygen consumption while improving cardiac output. Simply stated, NIV has been an undeniable game changer in the management of respiratory distress and failure for adults, children, and infants. NIV can be considered before tracheal intubation in children with acute respiratory failure, but, regardless of modality, it should not delay intubation if an invasive airway is indicated.
High-flow Nasal Canula
HFNC is a form of noninvasive support in respiratory failure for both oxygenation and ventilation, albeit much more the former than the latter. The heated and humidified air is delivered ideally at flow rates and fraction of inspired oxygen (Fi o 2 ) that match or exceed the needs of the patient in distress. By doing so, the work of breathing is reduced, and patients can find relief. Because the prongs are larger, higher flow rates can be accommodated. When these high flow rates are coupled with a closed mouth, there is an estimated 1 cm H 2 O of positive end-expiratory pressure (PEEP) for every 10 L/min. Although there are likely additional mechanisms at play, there is also alveolar recruitment and an increase in FRC. Additional advantages to HFNC include humidification, which may also serve to loosen secretions and decrease mucus plugging.
When starting infants on HFNC, flow rates of 1.5 to 2 L/kg/min are recommended to effectively decrease their work of breathing. Studies have found that the work of breathing in infants with bronchiolitis is between 1.6 and 1.8 L/kg/min. Fi o 2 should be titrated to reduce work of breathing and, as is generally accepted, maintain oxygen saturations greater than 90%.
Continuous Positive Airway Pressure and Bilevel Positive Airway Pressure
By nasal apparatus or face mask, CPAP has successfully treated patients with pediatric respiratory failure for some time. It has found particular success in supporting infants and small children with bronchiolitis. The augmentation of end-expiratory pressure and increased airway diameter effectively increases the FRC and decreases the work of breathing. The nasal apparatus can provide adequate support because many of these children are obligate nasal breathers and have difficulty overcoming the copious nasal secretions. Regardless of application device used, effective CPAP decreases capillary partial pressure of carbon dioxide, respiratory rate, heart rate, and Fi o 2 . CPAP has also been shown to be of use in pediatric pneumonia, heart failure, and asthma, although the exact beneficial mechanisms are still pending conclusive research, the mechanisms are likely similar to those known in adults.
Bilevel positive airway pressure (BiPAP) provides additional support in that there is an intermittent increase of positive pressure, which attempts to mimic more normal respiration by supporting inspiration. The benefits of BiPAP are similar to those of CPAP, but it is often initiated when patients require more support, particularly with ventilation or work of breathing. It is an option for severe asthma exacerbations in pediatric patients, as it is also used in adults with severe asthma, chronic obstructive pulmonary disease, pneumonia, and heart failure.
Choice of Noninvasive Support
Choosing the correct modality of noninvasive support can be difficult. Numerous factors influence the decision. The degree of respiratory distress, the cause of respiratory failure, and the patient’s age are among the primary considerations. Table 1 includes additional considerations.
| Patient Factors | Age Weight Degree of distress Cause of failure Underlying comorbidities Concurrent illness or injuries Diagnostic or procedural indications Mental status Caregiver support Last Meal |
| Physician Factors | Training Knowledge Experience Confidence |
| Support Staff | Nursing experience Nursing ratios Respiratory therapists |
| Facility | Additional physicians Equipment Supplies Facility use
|
| Disposition | Inpatient availability Intensivist support Transfer requirements
|
A prospective, multicenter study of pediatric intensive care unit (PICU) patients with respiratory failure investigated whether use of NIV and HFNC before intubation was associated with greater peri-intubation adverse events or more severe oxygen desaturation. There was no indication that using NIV before intubation was harmful to pediatric patients or increased risk of peri-intubation adverse effects. It did find that higher Fi o 2 use (>70%) was associated with more severe peri-intubation desaturations; however, this is a logical finding in that those patients who require a higher Fi o 2 with NIV and are still experiencing progressive respiratory failure are likely sicker and would, therefore, have less physiologic reserve and tolerance for the brief period of apnea associated with intubation.
A 2019 retrospective study of infants and young children admitted to the PICU for bronchiolitis observed a higher failure rate in those receiving HFNC as opposed to BiPAP or CPAP. Subjects ranged from 1 month to 2 years of age, and those patients placed on HFNC as the initial modality of choice tended to be older than those who started on BiPAP or CPAP.
Starting severe asthmatics on HFNC has shown a reduction in respiratory distress early in treatment in the emergency department.
Decision to definitive airway
Ideally, patients are at least partially resuscitated to optimize conditions for intubation. Pokrajac and colleagues found that pediatric patients less than the age of 1 year, with persistent hypoxemia, or in whom clinicians were unable to obtain a pulse oximetry reading before intubation, were more likely to experience peri-intubation cardiac arrest in the pediatric emergency department.
View from the Top
Once the decision to place an invasive airway is decided, it is important to have a systematic approach to preparation and team organization ( Table 2 ).
- 1.
Bring bed up to appropriate level for the operator.
- 2.
Ensure intravenous or intraosseous access is functional.
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Optimize patient positioning, with particular consideration of the head. Because children’s heads are larger in proportion to the rest of their bodies, optimal positioning often requires a shoulder roll or other support to bring the sternal notch up to the level of the tragus, which in turn aligns the laryngeal axis.
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Ensure multiple sizes of the adjunctive equipment, as well as the tracheal tube sizes, with the corresponding stylets, and syringe for cuff inflation.
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Proper monitoring equipment should also be thoughtfully applied, including preparation for end-tidal capnography. When available, preintubation and postintubation end-tidal capnography can be a useful adjunct in airway management.
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When the patient is properly positioned, equipment available, and team members poised, it may be beneficial to perform a brief time-out confirming patient identification and indication, and to ensure all involved are focused on the task at hand.
- 7.
Detailed description of various intubation techniques is beyond the scope of this article; however, they should be practiced and reviewed by emergency physicians regularly for maintenance of skills.
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