Acute Airway in a Child

Introduction

The acute airway in a child presents due to compromised airflow during ventilation. Immediate management is crucial due its potential for a life-threatening trajectory.

Pathophysiology

The paediatric airway is distinctly different from the adult airway in the following ways:1,2

• It has a smaller diameter and shorter length.
• The paediatric larynx is situated higher and more anteriorly.
• Children have larger heads relative to their body size.
• Children’s tongues are larger relative to the size of their oropharynx.
• The paediatric epiglottis is large and floppy.

These structural differences increase the airway’s susceptibility to obstruction. In narrow airways, small amounts of swelling or oedema result in proportionally larger percentage decreases in airway diameter.³ This decrease in diameter increases the resistance of the airway. Indeed, Pousielle’s Law shows that a fall in airway radius by half increases the resistance of the airway 16-fold:²

R = 8ηl/πr⁴ , where R = resistance and r = radius

Children also have a higher metabolic rate than adults. This physiological difference is explained by Kleiber’s Law, with younger children with smaller masses having higher metabolic rates, using more oxygen per gram of tissue. Babies have a faster heart rate, faster respiratory rate and feed more regularly because of their smaller body habitus and ability to move blood very quickly from the heart to peripheral tissues. They are also obligate nasal breathers for the first few months of life.² The natural physiology of children predisposes them to a low tolerance to airway pathology and rapid deterioration when the airway is compromised.⁴

Clinical Presentation

Clinical features vary based on the underlying pathology. An acute airway in a child can be caused by any of the following:5,6

• Croup (viral laryngotracheobronchitis).
• Anaphylaxis.
• Obstructive foreign body.
• Retropharyngeal abscess.
• Peritonsillar abscess.
• Epiglottitis or tracheitis.
• Airway burn such as from smoke inhalation.
• Trauma.

Clinical History

The history in a patient with an acute airway should be directed towards establishing the underlying pathology and identifying difficult to manage airways. It is vital to investigate the following:

• Potential for foreign body within the airway.
• Symptoms of upper respiratory tract infection.
• Feeding difficulties.
• Any surgeries or trauma to the airway or surrounding structures.
• Complications during birth or delivery or previous intubation.

An acute airway may present on a background of an underlying airway condition which increases the difficulty in managing the patient’s airway. Examples include subglottic stenosis, laryngeal atresia, laryngeal or tracheal webs, tonsillar hypertrophy and haemangiomas .3

Clinical Examination

The acute airway can be identified by observing a patient’s breathing. Examination of a child with an acute airway should be done cautiously to avoid causing distress, which could lead to laryngospasm.⁷ Inspection can be very informative. Respiratory distress in infants can be classified as moderate or severe based on the clinical features (see Table 1).

Table 1: Classifications of Respiratory Distress⁶

Congenital syndromes can have associated anatomical abnormalities which predispose patients to airway problems. Table 2 summarises some structural abnormalities and their associated syndromes.

Table 2: Structural Abnormalities and Associated Syndromes^2,3

The below image depicts laryngomalacia, a common cause of airway problems in paediatrics, due to soft laryngeal cartilages. Note the ‘floppy’ appearance of the cartilages, the lack of structure causing a partially obstructed airway. More information is available on our Laryngomalacia page, in the ENT section.

Dr Chaigasame, CC BY 4.0 , via Wikimedia Commons

Figure 1: an illustration depicting a normal larynx and that of a laryngomalacia patient.

Noisy Breathing

Obstructive airway pathology characteristically presents with stridor breath sounds. Stridor is a high pitched breathing noise which indicates pathology around the level of the larynx.⁷ The timing of the stridor is related to the anatomical level of the obstruction (See Table 3).

Table 3: Types of stridor

Other breath sounds include:

• Stertor: Snoring sound which arises from the level of the oropharynx or nasopharynx,

• Wheeze: High pitched expiratory sound from the lower airway,
• Gurgling: Wet sounding noise indicative of fluid in the airway.

Investigations

Immediate management of the acute airway should not be delayed by performing investigations. Stable patients may require imaging such as a chest x-ray in foreign body obstruction. Flexible nasendoscopy (FNE) can be performed to help identify the underlying pathology.⁴ This should only be attempted by trained, senior clinicians, such as ENT or anaesthetics registrars/consultants.

Cotton-Myer Grading of Subglottic Stenosis

Subglottic stenosis can be congenital or acquired. The former is an indication for tracheostomy, whereas the latter is commonly caused by prolonged periods of intubation. Cotton-Myer Grading is used in children to classify the severity of subglottic stenosis.

Table 4: Cotton-Myer Grading⁸

Management

The initial management of a patient presenting with an acute airway should be an A-E assessment. Oxygen therapy can be delivered via face mask or nasal cannula in patients with low oxygen saturations before initiating further management to address the underlying pathology. Senior help from ENT, anaesthetics, or intensive care should be sought early.

Emergency Airway Manoeuvres

In a patient with airway compromise, a head tilt chin lift can open up the airway. Children under 1 year of age should have their chin lifted into a neutral position to avoid overextension of the neck, whereas children over 1 can tolerate a normal head tilt chin lift. If a head tilt chin lift is found ineffective, or in the event of trauma, a jaw thrust can be performed to help maintain the airway.^6,9,10

By TeachMeSeries Ltd (2024)

Figure 2: A demonstration of the jaw thrust procedure.

Medications

Steroids (oral, nebulized, or parenteral), heliox (helium and oxygen) and nebulized adrenaline can be helpful in the management of an acute airway.

Airway Adjuncts

Oropharyngeal Airway

An oropharyngeal airway is sized from the level of the incisors to the angle of the mandible.³ Insertion of an oropharyngeal airway in a patient less than 8 years old should be under direct vision with the concave side facing downwards, whereas in children older than 8, the airway should be inserted upside down before being rotated 180˚ at the back of the hard palate (just like we do for adults).⁹

Nasopharyngeal Airway

Nasopharyngeal airways can be useful in maintaining airway patency in conscious patients. They are much better tolerated than oropharyngeal airways in conscious patients.

Supraglottic Airway- Laryngeal Mask Airway

Laryngeal mask airways (LMA) sit above the level of the vocal cords. If a patient requires ventilation and no-one who is skilled in intubation is available, then the insertion of a LMA should be considered.

By TeachMeSeries Ltd (2024)

Figure 3: A demonstration of laryngeal mask airway (LMA) insertion.

Subglottic Airway- Endotracheal Tube

Endotracheal tube (ETT) intubation below the subglottis creates a definitive airway for providing ventilatory support. Generally, there should be no more than 4 attempts of ETT intubation before failed intubation is declared.

In a failed ventilation situation, a supraglottic airway adjunct should be inserted as a secondary measure to ventilate the patient. If a supraglottic airway cannot be inserted, a final attempt should be made to ventilate the patient using a face mask. If all of these attempts are unsuccessful, the situation is declared a ‘Can’t Intubate Can’t Oxygenate’ (CICO) scenario.³

Cricothyroidotomy

In an unsuccessful intubation and oxygenation scenario, an emergency needle cricothyroidotomy or surgical cricothyroidotomy can be performed to re-establish an airway. This is usually performed by an ENT specialist. Cricothyroidotomy may be appropriate when the airway obstruction is at the level of the larynx or above; It involves creating an opening through the cricothyroid membrane into the trachea.⁹

References