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CHAPTER 19: Recognition and Management of the Difficult Paediatric Airway

INTRODUCTION

Managing a child's difficult airway is a significant challenge in anaesthesia. This situation is defined as difficulty in face mask ventilation, tracheal intubation, or both, as determined by a trained anaesthetist. To ensure effective management, it is important to understand normal airway anatomy, common problems that may arise, and the equipment used during these procedures.

ANATOMY OF RELEVANCE

Differences Between Child and Adult

The size, shape, and position of airways vary considerably between children and adults, which necessitates careful consideration when managing a paediatric patient.

Upper Airway in Newborns

The upper airway in newborns is smaller than in adults, and their larger tongue occupies more space in the oral cavity, which can obstruct ventilation.
Newborns are obligate nose-breathers, meaning they primarily breathe through their nose; their high-placed epiglottis further complicates oral ventilation, which is significant during the first 2-6 months of life.
There is little lymphoid tissue in the upper airway until 2 years of age; however, tonsils and adenoids grow substantially from 2-7 years, potentially leading to increased airway resistance.

Laryngeal Position

In infants, the larynx is positioned higher in the neck than in adults, with the hyoid bone located between the C3 and C4 vertebrae.
As a child matures, the glottis migrates down to the C5-C6 region.
The epiglottis in young children is U-shaped and becomes funnel-shaped as they develop, with a narrowed portion at the cricoid ring, making it vital to recognize when intubating.

CAUSES OF A DIFFICULT AIRWAY

Difficult airways are commonly classified into various categories:

Congenital Structural

Examples include craniofacial anomalies, such as micrognathia, Treacher Collins syndrome, and other malformations impacting the airway anatomy.

Inflammatory

Conditions such as croup, epiglottitis, and other inflammatory processes can cause airway obstruction or exacerbate existing difficulties.

Neoplastic

Tumors, cystic hygromas, or other shapes of neoplasia can also significantly impact airway patency.

Implications of Structural Differences

The structural and functional differences between adult and paediatric airways have important implications for intubation and ventilation techniques. Infants particularly exhibit higher oxygen consumption rates, increasing the urgency of effective airway management in obstruction cases compared to adults.

ASSESSMENT OF THE AIRWAY

Clinical History

Gathering a detailed medical history is crucial and should include information on breathing difficulties, feeding patterns, previous surgeries, and any history of anaesthesia complications.

Physical Examination

A thorough physical examination may reveal:

The child's overall appearance, including any distress.
Signs of respiratory compromise such as stridor, wheezing, or cyanosis.
Physical abnormalities within the oral cavity including oral and facial structures, neck mobility, the distribution of soft tissue, and the size of the tongue.

Pre-operative Investigations

Diagnostic tools like imaging (X-ray, CT scan) play a vital role in identifying structural abnormalities that could compromise airway management; however, limited cooperation from young patients may affect the efficacy of these investigations. Continuous oxygen saturation monitoring is also essential.

CLINICAL CLASSIFICATION OF A DIFFICULT AIRWAY

Classifying patients based on airway symptoms and clinical signs can assist in decision-making:

Type I: Normal respiratory function, minimal distress.
Type II: Known airway disease with moderate distress.
Type III: Notable physical abnormalities leading to significant distress.
Type IV: Severe airway obstruction necessitating immediate intervention.

ANAESTHESIA PLAN

It is essential to develop individualized anaesthesia plans based on the patient's specific airway and respiratory status. The plan should include alternative airway management strategies right from the beginning, especially for high-risk patients.

MANAGING AIRWAY DURING ANAESTHESIA

Techniques

Mask Ventilation: Proper positioning of the patient is critical for successful mask ventilation, given the anatomical changes in children.
Intubation Techniques: It is essential to use equipment that is appropriate for pediatric patients. For infants, straight blades are often preferable, as they facilitate better visualization of the larynx.
Alternative Devices: Devices such as the laryngeal mask airway (LMA) can serve as a temporary solution and may be particularly useful in certain scenarios.

EXTUBATION

Complications are common during the extubation process. It is crucial to perform extubation under controlled conditions, with all necessary equipment readily available to manage potential complications. Following specific protocols informed by pre-operative risk assessments will help increase the safety of the extubation process.

SUMMARY

A comprehensive assessment of the airway difficulties is vital to ensuring patient safety and operational effectiveness. Maintaining a calm and reassuring rapport with both the patient and guardians can aid in the process. It is essential always to have a clear plan for airway management, with trained personnel on standby for any emergencies.