Overview
Definition:
Pediatric airway assessment involves evaluating the anatomical and physiological characteristics of a child's airway to predict potential difficulties in ventilation and intubation
It considers unique pediatric features that differ significantly from adults, impacting management strategies.
Epidemiology:
Airway difficulties are a leading cause of morbidity and mortality in pediatric anesthesia and emergency medicine
Studies indicate that up to 10% of pediatric intubations may be difficult, with higher rates in neonates and infants.
Clinical Significance:
Accurate airway assessment in children is crucial for preventing hypoxemia, brain injury, and death
Early identification of potential airway challenges allows for appropriate preparation, equipment selection, and skilled personnel deployment, ensuring safer patient care and successful exam performance in DNB and NEET SS.
Anatomic Differences
Infant Vs Adult:
Infants have a relatively larger head, shorter neck, and prominent occiput
The tongue is disproportionately large compared to the oral cavity
The larynx is positioned higher in the neck (C3-C4 in infants vs
C5-C6 in adults) and is funnel-shaped, narrowing at the cricoid cartilage, which is the narrowest point of the pediatric airway.
Laryngeal Anatomy:
The pediatric epiglottis is omega-shaped and more anteriorly located
Vocal cords are shorter and angled anteriorly
The cricoid cartilage is the narrowest diameter, making it susceptible to edema and obstruction, and is a key consideration for endotracheal tube selection.
Tracheal Anatomy:
The trachea is shorter and narrower in children, with a steeper angle of branching at the carina
The right main bronchus originates at a less acute angle than in adults
Tracheal diameter decreases with age, necessitating precise tube sizing.
Nasal Obstruction:
Infants are obligate nasal breathers for the first few months of life, making nasal obstruction a significant concern that can lead to respiratory distress
Their small jaw size and anterior larynx also contribute to airway vulnerability.
Soft Tissues:
Children have larger tonsils and adenoids relative to their pharyngeal space, and a higher proportion of subcutaneous tissue around the airway, which can contribute to obstruction when swollen or edematous.
Positioning Considerations
Sniffing Position:
The "sniffing position" (neck flexion at the cervical spine and extension at the atlanto-occipital joint) is ideal for adults but may not be optimal for infants due to their large occiput
A small shoulder roll or head elevation might be necessary to align the oral, pharyngeal, and laryngeal axes in infants.
Head Elevation:
In infants, a shoulder roll (approximately 1-2 cm) is often used to elevate the occiput, bringing the external auditory meatus to the level of the sternal notch, thus optimizing airway alignment
Over-extension can kink the trachea, while under-extension can obstruct the airway.
Prone Positioning:
In certain situations, like managing severe airway obstruction or during some procedures, prone positioning might be used cautiously, but it requires careful monitoring for respiratory compromise and is generally avoided in unstable patients.
Lateral Positioning:
Lateral positioning may be helpful in some cases of posterior airway obstruction or during certain surgical procedures, but the potential for airway collapse must be considered and monitored.
Assessment Techniques
Visual Inspection:
Observe for signs of respiratory distress: tachypnea, retractions (supraclavicular, intercostal, subcostal), nasal flaring, grunting, cyanosis
Assess for facial anomalies, micrognathia, macroglossia, and neck masses.
Palpation:
Palpate the mandible for size and symmetry
Assess neck length and mobility
Identify the hyoid bone and thyroid cartilage to estimate laryngeal position.
Auscultation:
Listen for stridor (inspiratory, expiratory, biphasic), wheezing, and diminished breath sounds
Location of abnormal sounds can localize the obstruction
Presence of stridor suggests upper airway obstruction.
Airway Prediction Scores:
While not as standardized as in adults, elements from adult scores can be adapted
Key indicators include micrognathia, limited neck extension, large tongue, and history of difficult intubation or airway anomalies.
Fiberoptic Evaluation:
In elective settings or with suspected difficult airways, fiberoptic laryngoscopy or bronchoscopy can provide a direct view of the laryngeal structures, assess for anomalies, and evaluate glottic opening and vocal cord mobility
This is crucial for advanced planning.
Diagnostic Approach
History Taking:
Obtain history of previous airway issues, prematurity, genetic syndromes (e.g., Down syndrome, Pierre Robin sequence), congenital anomalies (e.g., choanal atresia, laryngomalacia), recurrent croup, stridor at birth, infections affecting the airway (e.g., epiglottitis, retropharyngeal abscess), and history of surgery or trauma to the head/neck.
Physical Examination:
Assess for dysmorphic features, micrognathia, retrognathia, macroglossia, neck masses, tracheal deviation, and extent of cervical spine mobility
Evaluate the oral cavity for tonsillar hypertrophy, posterior pharyngeal wall abnormalities, and tongue position.
Investigations:
Lateral neck X-ray can show steeple sign in croup or thumb sign in epiglottitis, but its sensitivity for detecting airway narrowing is limited
CT or MRI of the airway may be indicated for detailed evaluation of congenital anomalies or complex obstructions
Laryngoscopy is the gold standard for direct visualization.
Differential Diagnosis:
Consider common causes of pediatric airway obstruction: croup, epiglottitis, foreign body aspiration, anaphylaxis, angioedema, vocal cord paralysis, choanal atresia, tracheomalacia, laryngomalacia, Pierre Robin sequence, tumors, and abscesses
Each has distinct clinical presentations and requires specific management.
Management Implications
Equipment Selection:
Use appropriately sized laryngoscope blades (Miller blades are often preferred in infants for straight visualization), endotracheal tubes (consider uncuffed tubes in neonates and infants <8 years old due to the cricoid cartilage being the narrowest point), and suction catheters
Have multiple sizes readily available.
Ventilation Strategies:
Bag-mask ventilation may be challenging due to smaller tidal volumes and potential for gastric distension
Cricoid pressure might be applied to reduce aspiration risk, but its efficacy and potential to worsen obstruction are debated and should be used judiciously based on clinical context.
Intubation Technique:
Maintain optimal head positioning
Use a stylet within the endotracheal tube for rigidity
Avoid excessive manipulation
Consider awake intubation or video laryngoscopy in anticipated difficult airways
Be prepared to use supraglottic airway devices or cricothyroidotomy if intubation fails.
Pharmacological Considerations:
Consider medications for sedation, analgesia, and neuromuscular blockade based on the child's age, weight, and physiological status
Bronchodilators may be useful if bronchospasm is present
Steroids can reduce airway edema in croup and epiglottitis.
Key Points
Exam Focus:
DNB and NEET SS candidates must understand the funnel shape of the pediatric larynx and the cricoid cartilage as the narrowest point
Recall the higher laryngeal position and the importance of the sniffing position (modified for infants).
Clinical Pearls:
Always prepare for a difficult airway in pediatric patients
Have all airway equipment, including smaller sizes, readily accessible
Prioritize oxygenation over visualization
Be comfortable with alternative airway devices and techniques.
Common Mistakes:
Failure to recognize obligate nasal breathing in infants
Using adult airway assessment principles without modification
Incorrect sizing of endotracheal tubes
Over-extension or under-extension of the neck leading to airway obstruction
Inadequate preparation for a difficult airway.