Paediatrics
PA_1.1 Describe the anatomy of the neonatal and paediatric airway, how this changes with age and the implications for airway management
Anatomy of the Neonatal and Paediatric Airway and Its Changes with Age
Neonatal and Paediatric Airway Anatomy
Head and Neck
Relatively large occiput: Tends to flex the neck when supine, requiring careful positioning for airway alignment.
Short neck: Leads to reduced anatomical distance for airway instrumentation.
Tongue
Proportionally larger in relation to the oral cavity: Increases the risk of airway obstruction.
Nasal Airway
Neonates are obligate nasal breathers: Nasal obstruction (e.g., secretions, edema) can lead to significant respiratory distress.
Epiglottis
Larger, floppy, and omega-shaped: Positioned more anteriorly and angled, making visualization during laryngoscopy more challenging.
Larynx
Higher and more anterior (C2–C3 in neonates vs. C4–C5 in adults): This makes a straight laryngoscope blade more effective.
Narrowest part is the cricoid cartilage (in neonates and infants) compared to the vocal cords in older children and adults.
Trachea
Shorter and more compliant: Increases the risk of endotracheal tube (ETT) displacement and dynamic airway collapse.
Cartilaginous Support
Airway structures are more compliant and prone to collapse under negative pressure or with external compression.
Changes with Age
Laryngeal Position
Larynx descends with age (C4–C5 by adolescence).
Changes in laryngeal anatomy lead to the vocal cords becoming the narrowest part of the airway.
Airway Size and Shape
Airway diameter increases with growth, reducing resistance to airflow.
The cricoid ring becomes less prominent as the airway transitions to an adult-like configuration.
Neck and Head Proportions
Relative size of the occiput decreases, reducing the need for a towel roll or positioning aids for airway alignment.
Tongue and Epiglottis
Tongue size relative to the oral cavity decreases.
The epiglottis becomes less floppy and more linear, facilitating improved visualization during laryngoscopy.
Trachea
Length and rigidity increase, reducing the risk of tube displacement and collapse.
Implications for Airway Management
Positioning
Neonates and infants require a shoulder roll or head tilt to achieve the ""sniffing position"" due to the large occiput.
Airway Instrumentation
Use a straight blade (e.g., Miller) for neonates and infants to lift the floppy epiglottis.
Ensure appropriate ETT size (smaller, uncuffed tubes often preferred in neonates to avoid cricoid injury).
Monitoring and Ventilation
Higher risk of airway obstruction due to tongue size and compliance of airway structures.
Avoid excessive pressure during bag-mask ventilation to prevent airway collapse or gastric insufflation.
Tube Placement
Carefully secure the ETT due to the short trachea and risk of displacement.
Confirm placement with capnography and auscultation, as malposition can occur easily.
Anatomical Challenges
Be prepared for difficulty visualizing the larynx during intubation in neonates and infants.
Anticipate rapid desaturation due to higher metabolic demand and limited oxygen reserves.
Equipment
Use age-appropriate airway adjuncts (e.g., oral airways, laryngoscope blades, and supraglottic devices).
Ensure availability of smaller-sized endotracheal and nasopharyngeal tubes.
Understanding these anatomical differences and their progression with age ensures effective and safe airway management for neonates and pediatric patients.
PA_1.2 Describe airway and ventilatory equipment specific for paediatric patients, including: • Estimation of ETT size • Estimation of LMA of appropriate size • Accurate placement of ETT including fixation techniques • Use of cuffed and uncuffed tubes • Breathing circuits
Airway and Ventilatory Equipment for Paediatric Patients
Managing paediatric airways requires appropriately sized equipment and careful attention to anatomical and physiological differences. Below is a detailed discussion of essential equipment and techniques for paediatric airway management.
1. Estimation of Endotracheal Tube (ETT) Size
A. Formula for Uncuffed ETT Size
Age-Based Formula: ( \text{ETT size (internal diameter, mm)} = \frac{\text{Age in years}}{4} + 4 )
Example: A 4-year-old child: ( \frac{4}{4} + 4 = 5.0 , \text{mm} ).
B. Formula for Cuffed ETT Size
Use one size smaller than for uncuffed tubes: ( \text{ETT size for cuffed tube} = \frac{\text{Age in years}}{4} + 3.5 ).
C. Alternative Methods
Compare to the child’s little finger diameter.
Use a Broselow tape for weight-based sizing.
2. Estimation of Laryngeal Mask Airway (LMA) Size
A. Size Selection
Weight-Based Guidelines:
Size 1: < 5 kg.
Size 1.5: 5–10 kg.
Size 2: 10–20 kg.
Size 2.5: 20–30 kg.
Size 3: 30–50 kg.
B. Insertion Technique
Ensure correct positioning with the tip of the cuff in the hypopharynx.
Confirm placement with capnography and chest movement.
3. Accurate Placement of Endotracheal Tube
A. Depth of Insertion
Formula for ETT depth (at lips): ( \text{Depth (cm)} = \text{ETT size} \times 3 ).
Example: For a 4.0 mm ETT, depth = ( 4.0 \times 3 = 12 , \text{cm} ).
B. Confirmation of Placement
Use multiple modalities:
Capnography: Continuous waveform confirms tracheal placement.
Auscultation: Equal breath sounds bilaterally and absence over the stomach.
Chest Rise: Symmetrical movement with ventilation.
C. Fixation Techniques
Use adhesive tape or commercial tube holders.
Anchor the tube securely but avoid excessive pressure on the lips or skin.
4. Use of Cuffed and Uncuffed Tubes
A. Cuffed Tubes
Advantages:
Better airway seal and lower gas leak.
Reduced need for frequent tube changes during surgery.
Disadvantages:
Risk of tracheal injury if overinflated.
Pressure Monitoring: Ensure cuff pressure ≤ 20 cmH(_2)O to prevent mucosal damage.
B. Uncuffed Tubes
Advantages:
Lower resistance to airflow in smaller airways.
Safer in neonates and infants with narrow airways.
Disadvantages:
Potential for leaks requiring higher ventilation pressures.
5. Breathing Circuits
A. Types of Circuits
T-Piece Circuit:
Common in neonates and infants (<10 kg).
Minimal dead space and low resistance.
Bain Circuit:
Suitable for children up to 20–30 kg.
Lightweight and efficient for spontaneous or controlled ventilation.
Circle Circuit:
Used in older children and adolescents (>20 kg).
Suitable for extended surgical procedures with efficient gas delivery and heat/humidity conservation.
B. Adjustments for Paediatric Patients
Use of smaller reservoir bags and low compliance tubing to match tidal volume needs.
Adjust fresh gas flows to prevent rebreathing in non-rebreathing circuits.
6. Safety Considerations
Always have multiple sizes of ETTs and LMAs available.
Monitor ventilation closely with capnography, pulse oximetry, and airway pressure measurements.
Avoid overinflation of cuffs to prevent airway trauma.
Maintain proper humidification during prolonged ventilation.
Conclusion
Effective management of the paediatric airway requires correctly sized equipment and adherence to age-appropriate techniques. Accurate placement, secure fixation, and proper circuit selection are vital to ensure safety and optimal ventilation. Regular training and preparedness for airway challenges enhance outcomes in paediatric anaesthesia.
PA_1.3 Describe how preoxygenation and rapid sequence induction may be modified in paediatric patients
Preoxygenation and Rapid Sequence Induction (RSI) in Paediatric Patients
Preoxygenation and RSI in paediatric patients require specific modifications to account for their physiological differences, smaller anatomical structures, and heightened susceptibility to hypoxia.
1. Preoxygenation in Paediatrics
Challenges in Paediatrics:
Higher Oxygen Consumption: Infants and children consume oxygen at 6–8 mL/kg/min, compared to 3–4 mL/kg/min in adults.
Lower Functional Residual Capacity (FRC): Paediatrics have a lower FRC, providing less oxygen reserve.
Higher Alveolar Ventilation Rate: This promotes faster oxygenation but also faster desaturation during apnoea.
Modifications:
Optimal Mask Fit: Use age-appropriate masks to ensure a good seal and minimize leaks.
High-Flow Oxygen: Administer oxygen at high flow rates (≥10 L/min) to maximize alveolar oxygenation.
Calming Measures: Allow parental presence, play videos, or use distraction techniques to reduce anxiety and improve compliance.
Tidal Volume Breathing vs. Vital Capacity Manoeuvres: While vital capacity breathing can achieve quicker preoxygenation, tidal volume breathing over 2–3 minutes is often more practical for uncooperative children.
Nasal Oxygenation: Use nasal cannula during preoxygenation and apnoeic oxygenation to prolong the safe apnoea time.
2. Rapid Sequence Induction in Paediatrics
Challenges in Paediatrics:
Risk of Hypoxia: The combination of lower FRC and higher oxygen consumption means paediatrics desaturate rapidly.
Small Airway Anatomy: Increases the risk of airway obstruction and difficult intubation.
Physiological Response to Drugs: Haemodynamic responses to induction agents are more pronounced, especially in neonates and infants.
Modifications:
Preparation:
Have all equipment, including appropriately sized airway devices (ET tubes, LMAs), readily available.
Prepare suction and drugs for emergency management.
Induction Agents:
Use age-appropriate doses of induction agents (e.g., propofol, thiopental).
Consider ketamine for haemodynamic stability in critically ill or hypovolaemic children.
Neuromuscular Blockade:
Succinylcholine (1–2 mg/kg IV) is often used for rapid paralysis.
If contraindicated (e.g., hyperkalaemia, neuromuscular disorders), use rocuronium (1.2 mg/kg IV) as an alternative.
Cricoid Pressure:
Apply cricoid pressure cautiously, balancing the risk of regurgitation with the potential for airway obstruction.
Ventilation Prior to Intubation:
Gentle mask ventilation may be required to prevent hypoxia, especially in younger children. Use low-pressure ventilation to avoid gastric insufflation.
Apnoeic Oxygenation:
Continue nasal oxygenation during apnoea to extend safe apnoea time.
3. Special Considerations
Uncooperative Patients: In younger or anxious children, premedication with oral midazolam or inhalational induction with sevoflurane may be needed before RSI.
Neonates and Infants: Their immature physiological systems make them more prone to bradycardia and hypotension; atropine (10–20 µg/kg IV) is often given prophylactically.
Emergency Scenarios: Always have a difficult airway algorithm and rescue devices ready (e.g., LMAs, surgical airway).
By tailoring preoxygenation and RSI to paediatric-specific needs, anaesthetists can optimize oxygenation, ensure rapid and safe induction, and minimize complications.
PA_1.4 Describe positioning for direct laryngoscopy in paediatric patients
Positioning for Direct Laryngoscopy in Paediatric Patients
Positioning for direct laryngoscopy in paediatric patients differs from adults due to anatomical and physiological differences. The goal is to align the oral, pharyngeal, and laryngeal axes to optimize visualization of the glottis and facilitate intubation.
Key Anatomical Considerations in Paediatrics
Larger Occiput: Infants and young children naturally have a more flexed neck position due to the prominent occiput.
Anteriorly Positioned Larynx: The larynx is higher and more anterior (C3–C4 in infants vs. C5–C6 in adults).
Floppy Epiglottis: This requires lifting with the tip of the laryngoscope blade for optimal glottic view.
Optimal Positioning for Laryngoscopy
Sniffing Position:
The classic sniffing position aligns the oral, pharyngeal, and laryngeal axes.
Achieved by:
Infants and Young Children: Use a shoulder roll or towel under the shoulders to counteract the naturally flexed neck. Avoid excessive neck flexion.
Older Children: A small head elevation may suffice, similar to adults.
Neutral Head Position (for Neonates and Infants):
In neonates, a neutral head position is often adequate due to the natural alignment caused by the larger occiput.
Flexion-Extension Balance:
Ensure slight neck flexion with head extension at the atlanto-occipital joint. This prevents airway obstruction and enhances glottic view.
Steps for Positioning
Preparation:
Place the child supine on the operating table.
Assess the occiput prominence and airway alignment before adjusting.
Shoulder Roll (if needed):
Use a rolled towel or soft pad under the shoulders to elevate the chest and extend the neck.
Head Elevation (if required):
Place a small pad under the head in older children to achieve optimal neck flexion and head extension.
Midline Positioning:
Ensure the head and neck are straight and midline to avoid misalignment.
Confirm Axial Alignment:
Visualize alignment of the external auditory meatus with the sternal notch as a quick guide.
Additional Tips
Avoid Overextension: Excessive extension can obstruct the airway and hinder visualization.
Assistant Support: An assistant can stabilize the head if needed, especially in younger or less cooperative patients.
Check Glottic View: Adjust positioning dynamically if the glottis is not visible during laryngoscopy.
PA_1.5 Describe techniques for endotracheal intubation in paediatric patients
Techniques for Endotracheal Intubation in Paediatric Patients
Endotracheal intubation in paediatric patients requires a tailored approach due to their anatomical and physiological differences. These techniques ensure safe and effective airway management across various age groups and clinical scenarios.
Preparation
Equipment Selection:
ET Tube:
Cuffed or uncuffed based on patient size and clinical need.