Paediatric Airway Anatomy & Physiology

Quick Answer

Paediatric airway management requires understanding of profound anatomical and physiological differences from adults. Infants have a proportionally larger occiput, larger tongue, higher larynx (C3-C4), and omega-shaped epiglottis. The cricoid ring is classically the narrowest point, though recent MRI studies suggest the glottis may be functionally narrower. Higher oxygen consumption (6-8 mL/kg/min), reduced functional residual capacity (FRC), and low closing capacity cause rapid desaturation. Pre-oxygenation provides less buffer time than in adults. Positioning requires shoulder roll alignment rather than sniffing position. Age-appropriate equipment sizing and understanding of airway reflexes (increased risk of laryngospasm in infants) are critical for safe anaesthesia management (PMID: 18452140, 21975005).

Paediatric Anatomy & Physiology

Anatomical Differences

The infant airway is not merely a scaled-down adult airway; it possesses distinct structural characteristics that evolve throughout childhood. These differences significantly impact airway management strategies and equipment selection (PMID: 18452140).

Occiput and Head Positioning

Infants have a proportionally larger occiput compared to adults. When placed supine, the occiput causes neck flexion, potentially obstructing the airway. This anatomical feature necessitates the use of a shoulder roll to align the oral, pharyngeal, and laryngeal axes, rather than the traditional adult "sniffing position" which relies on head elevation (PMID: 25102005). The large occiput also affects positioning for laryngoscopy and can contribute to airway obstruction during anaesthesia if the head is not adequately supported.

Tongue Size and Position

The infant tongue is relatively large in proportion to the oral cavity, occupying a greater percentage of the oropharyngeal space. This makes tongue displacement more difficult during laryngoscopy and increases the risk of airway obstruction, particularly in supine positions or when muscle tone is reduced under anaesthesia (PMID: 21975005). The large tongue also contributes to the increased work of breathing in infants and may predispose to upper airway obstruction during emergence from anaesthesia.

Laryngeal Position

The larynx is positioned more cephalad in infants than in adults. In neonates and young infants, the larynx is located at the level of C3-C4 vertebrae, compared to C4-C5 in adults (PMID: 12606894). This higher position has several implications: it makes anterior laryngeal structures more accessible but also means that the trachea is shorter, increasing the risk of endobronchial intubation. The more cephalad position also affects the angle of approach during laryngoscopy and influences the selection of airway equipment.

Epiglottis Shape and Function

The infant epiglottis is longer, stiffer, and characteristically "omega-shaped" (Ω), in contrast to the flatter, more flexible adult epiglottis (PMID: 18452140). Additionally, the infant epiglottis is positioned more horizontally, overlying the glottic opening. This configuration necessitates a different approach to laryngoscopy, often requiring the use of a Miller (straight) blade to lift the epiglottis directly, rather than the Macintosh (curved) blade which is commonly used in adults. The stiff, omega-shaped epiglottis can also make visualization of the glottis more challenging in infants.

Narrowest Point of Airway

Classically, the cricoid cartilage has been described as the narrowest point of the paediatric airway, forming a "funnel-shaped" airway that is narrowest at the subglottic region (PMID: 12606894). This understanding led to the historical preference for uncuffed tracheal tubes in children. However, recent MRI studies have challenged this concept, suggesting that in many children, particularly those over one year of age, the glottic opening may be the functionally narrowest part of the airway (PMID: 12606894). The cricoid ring remains the only complete circular cartilaginous ring in the airway, which has important implications for pressure-induced injury from cuff tubes.

Vocal Cord Anatomy

The infant vocal cords are angled more anteriorly than in adults. This anterior angulation can cause the tip of a tracheal tube to become caught in the anterior commissure during intubation attempts, potentially leading to difficulties in tube placement or vocal cord trauma (PMID: 22114284). The infant vocal cords are also shorter and have a different elasticity compared to adults, affecting both voice production and the mechanics of intubation.

Mainstem Bronchus Angle

The infant mainstem bronchi emerge from the trachea at approximately equal angles (both around 55°), whereas in adults the right mainstem bronchus is more vertical (approximately 25°) compared to the left (approximately 45°) (PMID: 21975005). This more symmetrical division in infants reduces the natural tendency for right mainstem intubation compared to adults, though the risk remains present. The shorter trachea in infants means that even slight advancement of an appropriately sized tube can result in endobronchial intubation, necessitating careful tube positioning and verification.

Physiological Differences

Oxygen Consumption

Infants have a significantly higher metabolic rate compared to adults, consuming oxygen at approximately 6-8 mL/kg/min, compared to approximately 3 mL/kg/min in adults (PMID: 21975005). This elevated oxygen consumption, combined with a smaller absolute oxygen reserve, results in extremely rapid desaturation during periods of apnea or hypoventilation. The high oxygen demand means that pre-oxygenation provides a shorter duration of apnoea tolerance in infants compared to adults. During general anaesthesia, maintaining adequate oxygen delivery becomes even more critical due to the increased metabolic requirements and limited oxygen reserves.

Functional Residual Capacity

Functional residual capacity (FRC) is reduced in infants relative to body weight and oxygen demand. The infant FRC is approximately 25-30 mL/kg, compared to approximately 30-35 mL/kg in adults, but when considered in relation to the higher oxygen consumption (VO2), the infant has a much lower oxygen reserve (PMID: 30234479). This "low reservoir, high demand" state means that infants can desaturate within seconds to minutes of apnea, compared to several minutes in adults. The reduced FRC also contributes to the rapid equilibration of inhaled anaesthetic agents, resulting in faster induction and emergence times with inhalational anaesthetics.

Lung and Chest Wall Compliance

The infant chest wall is highly compliant due to its cartilaginous composition, while the lungs have relatively low compliance (PMID: 30234479). This compliance mismatch has several important physiological consequences. During respiratory distress, the highly compliant chest wall allows for marked retractions as the infant attempts to generate negative intrathoracic pressure. The low lung compliance predisposes infants to atelectasis, particularly during general anaesthesia when respiratory muscle tone is reduced. The combination of these factors contributes to the increased work of breathing in infants and may necessitate higher airway pressures during positive pressure ventilation.

Closing Capacity

Closing capacity (CC) is higher in infants and often exceeds FRC during normal tidal breathing (PMID: 30234479). This means that small airways may close and collapse during normal ventilation, leading to increased physiologic dead space and intrapulmonary shunting. The tendency for airway closure contributes to ventilation-perfusion (V/Q) mismatch and predisposes infants to hypoxemia, particularly during anaesthesia when FRC is further reduced. The high closing capacity also means that positive end-expiratory pressure (PEEP) may be more beneficial in infants to maintain airway patency and prevent atelectasis.

Respiratory Control

The control of breathing in infants is immature compared to adults. The ventilatory response to hypercarbia is blunted, and the response to hypoxemia is biphasic, with an initial brief period of hyperventilation followed by respiratory depression (PMID: 21975005). This immature respiratory control system increases the risk of apnea, particularly during emergence from anaesthesia or in the postoperative period. Infants are also more susceptible to respiratory depression from opioids and other sedative medications, requiring careful dose titration and monitoring.

Age-Group Specific Considerations

Neonatal (0-28 days)

The neonatal airway is the most anatomically and physiologically distinct from the adult airway. The larynx is at the highest position (C2-C3), the tongue occupies a greater proportion of the oropharynx, and the epiglottis is proportionally larger and more omega-shaped (PMID: 18452140). Neonates have the highest oxygen consumption relative to body weight and the most reduced FRC, making them the most vulnerable to rapid desaturation. Airway reflexes are particularly active in neonates, increasing the risk of laryngospasm during light anaesthesia (PMID: 22114284). The neonatal airway is also more susceptible to obstruction from supraglottic airway devices due to the highly compliant tissues and relatively large tongue.

Infant (1-12 months)

During the first year of life, the airway anatomy begins to transition toward the adult pattern. The larynx gradually descends from the neonatal position, and the relative size of the tongue decreases (PMID: 12606894). However, the infant airway still retains many neonatal characteristics, including a high larynx, large tongue, and omega-shaped epiglottis. The MAC (minimum alveolar concentration) for inhalational agents reaches its peak in infants aged 1-6 months, being approximately 50% higher than in adults (PMID: 21975005). This period represents the highest risk for perioperative respiratory complications, including laryngospasm, bronchospasm, and postoperative apnea.

Toddler (1-3 years)

By toddler age, the larynx has descended to approximately the C4 level, and the airway dimensions have increased significantly. The epiglottis becomes less omega-shaped, though it remains relatively stiff and long compared to adults (PMID: 25102005). Toddlers have a higher incidence of upper respiratory tract infections (URTIs), which can significantly increase airway reactivity and the risk of perioperative respiratory complications (PMID: 28406208). The psychological development of toddlers also presents challenges, with increased anxiety and potential non-cooperation, which may necessitate premedication or alternative induction strategies.

Preschool (3-5 years)

Preschool children continue to show anatomical progression toward adult airway characteristics. The larynx is positioned at approximately C4-C5, and the cricoid ring becomes less circular and more ovoid (PMID: 12606894). The airway size increases, allowing for the safe use of cuffed tracheal tubes in many children. Airway reflexes remain active, and the incidence of URTIs continues to be high, contributing to perioperative respiratory risk. Preschool children may have significant dental issues, including loose or missing primary teeth, which must be considered during airway manipulation.

School Age (5-12 years)

By school age, the airway anatomy closely approximates that of adults, though dimensions remain smaller. The larynx is at the adult position (C4-C5), the epiglottis is less stiff, and the tongue is proportionally smaller (PMID: 25102005). The risk of rapid desaturation is reduced compared to younger children, though children still desaturate faster than adults due to higher oxygen consumption relative to FRC. Airway management in school-age children often follows adult protocols, with appropriate size adjustments for equipment and drug dosing. However, children in this age group may have increased anxiety, which can complicate induction.

Adolescent (12-18 years)

Adolescent airway anatomy is essentially adult in structure, though considerations must be made for puberty-related changes, including increased size and the possibility of obesity. The airway reflexes are similar to adults, and the risk of desaturation is comparable (PMID: 22114284). However, obesity, which is increasingly common in adolescents, can significantly complicate airway management by reducing lung volumes, increasing the work of breathing, and potentially making mask ventilation and laryngoscopy more difficult. Psychological factors, including body image and anxiety, may also influence perioperative management.

Anaesthetic Management

Airway Equipment Selection

Appropriate selection of airway equipment is critical for safe paediatric airway management. Tracheal tube size should be based on age, with uncuffed tubes traditionally used for children under 8 years of age (PMID: 19807530). However, the use of cuffed paediatric tubes has become increasingly common, with modern microcuff tubes designed to provide a better seal at lower pressures (PMID: 19807530). When using cuffed tubes in children, appropriate size selection and cuff pressure monitoring are essential to prevent subglottic injury. For uncuffed tubes, an audible air leak at 15-25 cm H2O suggests appropriate size.

Miller (straight) blades are generally preferred for infant laryngoscopy due to the high, anterior position of the larynx and the omega-shaped epiglottis (PMID: 25102005). Macintosh (curved) blades may be used in older children, particularly those with more adult-like airway anatomy. Oral airways should be sized appropriately, with the length measured from the corner of the mouth to the angle of the mandible. Nasal airways are rarely used in infants due to the risk of adenoid obstruction and epistaxis.

Induction Techniques

Both intravenous and inhalational induction techniques can be used in paediatric patients, with the choice depending on patient age, cooperation, and clinical circumstances (PMID: 28406208). Inhalational induction with sevoflurane is commonly used in uncooperative young children due to its pleasant odour, rapid onset, and minimal airway irritation. Sevoflurane also causes less respiratory depression compared to other inhalational agents, which is particularly important in children who may be prone to rapid desaturation.

Intravenous induction is preferred in older, cooperative children and in emergency situations where rapid airway control is required. Propofol is commonly used for intravenous induction in children, with appropriate dose adjustments based on age and size. Ketamine may be considered for induction in children with reactive airway disease or in situations where maintenance of cardiovascular stability is critical. Regardless of induction technique, appropriate monitoring and preparation for airway emergencies is essential.

Airway Maintenance Strategies

Multiple airway maintenance strategies are available for paediatric patients, each with specific advantages and considerations. Supraglottic airway devices (SGAs) have become increasingly popular in paediatric anaesthesia due to ease of insertion, reliable seal, and reduced risk of airway trauma (PMID: 28406208). However, SGAs may be less effective in infants due to the highly compliant tissues and large tongue, which can compromise the seal.

Endotracheal intubation remains the gold standard for airway protection, particularly for procedures involving the airway, head and neck surgery, or when positive pressure ventilation is anticipated. In recent years, cuffed tracheal tubes have become increasingly common in paediatric practice, with modern microcuff tubes designed to provide a reliable seal with low cuff pressures (PMID: 19807530). Cuffed tubes offer several advantages, including improved seal, reduced need for tube changes, and better protection against aspiration.

Monitoring Requirements

Comprehensive monitoring is essential during paediatric anaesthesia, with specific attention to airway and respiratory parameters. Capnography is mandatory for confirming endotracheal tube placement and monitoring ventilation (PMID: 22114284). Pulse oximetry is critical for detecting hypoxemia, which can develop rapidly in children. Airway pressures should be monitored, particularly during positive pressure ventilation, to detect increases that may indicate airway obstruction, bronchospasm, or equipment malposition.

Heart rate and rhythm must be continuously monitored, as bradycardia is often the first sign of hypoxemia in infants. Blood pressure monitoring should be age-appropriate, with cuff size adjusted to the child's arm circumference. In infants and young children, invasive arterial monitoring may be considered for major procedures or in patients with significant comorbidities.

Extubation Considerations

Extubation in paediatric patients requires careful timing and technique to minimize complications. The child should be fully awake with return of protective airway reflexes before extubation (PMID: 22114284). Deep extubation may be considered in selected cases to reduce the risk of laryngospasm, but this technique is controversial and requires considerable experience. The oropharynx should be suctioned under direct visualization to avoid stimulating the airway.

The position of the tracheal tube should be rechecked prior to extubation to ensure it has not migrated, as the increased compliance of the paediatric airway can allow tube movement with changes in head position. After extubation, children should be monitored for signs of airway obstruction, laryngospasm, or respiratory depression, particularly in the recovery period. Supplemental oxygen should be readily available, and equipment for re-intubation should be immediately accessible.

Perioperative Care

Pre-operative Assessment

A thorough pre-operative assessment is essential for identifying airway-related risk factors in paediatric patients. History of prematurity, particularly if associated with bronchopulmonary dysplasia, significantly increases the risk of perioperative respiratory complications (PMID: 22114284). Recent upper respiratory tract infection (URTI) is also a significant risk factor, with increased risk of laryngospasm, bronchospasm, and oxygen desaturation. The decision to proceed with elective surgery following a URTI should be individualized based on symptom severity, timing, and procedure urgency.

Congenital airway anomalies, including laryngomalacia, tracheomalacia, subglottic stenosis, and vascular rings, must be identified preoperatively, as these conditions significantly impact airway management strategies. A history of snoring or witnessed apneas may suggest obstructive sleep apnea, which is associated with increased perioperative respiratory complications. Previous difficult intubations or airway emergencies should be identified, and appropriate preparations made for the current procedure.

Fasting Guidelines

Paediatric fasting guidelines have evolved in recent years, with a trend toward liberalization of clear fluid intake to improve patient comfort and reduce the risk of dehydration (PMID: 28406208). Current guidelines generally recommend clear fluids up to 1 hour before induction, breast milk up to 4 hours before induction, and solid food/formula up to 6-8 hours before induction. Adherence to fasting guidelines is critical to reduce the risk of aspiration, though the actual incidence of aspiration in children is low.

In emergency situations where the stomach may not be empty, a rapid sequence induction with cricoid pressure may be considered. However, cricoid pressure in infants may be less effective than in adults due to the cartilaginous airway and may actually worsen the laryngeal view during laryngoscopy. In such cases, alternative airway management strategies, including awake intubation or the use of SGAs, may be considered.

Temperature Regulation

Infants and young children are particularly susceptible to perioperative hypothermia due to their high surface area-to-body weight ratio, limited subcutaneous fat, and immature thermoregulatory mechanisms (PMID: 21975005). Hypothermia can prolong recovery from anaesthesia, increase the risk of respiratory complications, and contribute to coagulopathy. Active warming measures should be employed for all paediatric patients, particularly neonates and infants.

Forced air warming devices are effective and should be used preoperatively, intraoperatively, and postoperatively. The operating room temperature should be increased for paediatric cases, particularly for neonates and infants. Intravenous fluids and irrigation solutions should be warmed. Temperature monitoring is essential, with both core and peripheral temperature measurements considered in small infants. The goal is to maintain normothermia throughout the perioperative period, as hypothermia has been associated with increased morbidity and mortality in paediatric patients.

Fluid Management

Paediatric fluid management requires careful attention to maintenance requirements, fasting deficit, and ongoing losses (PMID: 21975005). The Holliday-Segar formula (4-2-1 rule) remains the standard for calculating maintenance fluid requirements based on caloric expenditure. For neonates and infants, maintenance fluids are typically 100 mL/kg/day, decreasing to 60-70 mL/kg/day for older children.

Current recommendations favor isotonic crystalloids (such as 0.9% saline or Ringer's lactate) for maintenance and replacement fluids in children, avoiding hypotonic solutions that can cause hyponatremia (PMID: 21975005). Routine glucose administration is not recommended for most children beyond the neonatal period, as endogenous glucose production is typically adequate. However, glucose-containing solutions should be considered for neonates, malnourished children, and those undergoing prolonged procedures.

Paediatric Emergencies

Laryngospasm Management

Laryngospasm is a common and potentially serious airway emergency in paediatric anaesthesia, occurring in approximately 1-10% of paediatric cases depending on age and risk factors (PMID: 28406208). Laryngospasm is characterized by adduction of the true vocal cords and closure of the glottic aperture, resulting in airway obstruction. Risk factors include young age, recent URTI, airway manipulation, light anaesthesia, and procedures involving the airway.

Management of laryngospasm should be systematic and prompt. Initial measures include removing airway stimulation, calling for assistance, and applying 100% oxygen with positive pressure. Jaw thrust and chin lift should be performed to open the airway. Positive pressure ventilation with continuous positive airway pressure (CPAP) should be attempted, using 10-15 cm H2O pressure in infants and 15-20 cm H2O in older children (PMID: 28406208). If laryngospasm persists despite these measures, intravenous succinylcholine (0.1-0.2 mg/kg) may be administered to break the spasm. In rare, refractory cases, needle cricothyroidotomy or tracheostomy may be required.

Bronchospasm Management

Bronchospasm occurs in approximately 1-5% of paediatric anaesthetic cases, with higher rates in children with reactive airway disease or recent URTI (PMID: 22114284). Clinical manifestations include wheezing, increased airway pressures, and decreased expiratory flow. The first priority is to deepen anaesthesia and increase inspired oxygen concentration. Positive pressure ventilation should be initiated if not already in place, with careful attention to avoid barotrauma.

Bronchodilators are the mainstay of treatment for bronchospasm. Inhaled albuterol (salbutamol) should be administered, typically 2.5-5 mg via nebulizer or 4-8 puffs via metered-dose inhaler with spacer (PMID: 22114284). Systemic steroids, such as hydrocortisone (1-2 mg/kg) or dexamethasone (0.1-0.2 mg/kg), may be administered to reduce airway inflammation. For refractory bronchospasm, intravenous epinephrine (0.01-0.02 mg/kg) may be considered. Magnesium sulfate (40-50 mg/kg IV) may also be beneficial in severe cases, though evidence in paediatric anaesthesia is limited.

Cardiac Arrest in Children

Cardiac arrest in paediatric patients is most commonly respiratory in origin, emphasizing the critical importance of airway management and ventilation (PMID: 21975005). The "Hs and Ts" mnemonic remains useful for identifying reversible causes: hypoxia, hypovolemia, hypothermia, hypo/hyperkalemia, hydrogen ions (acidosis), hypoglycemia, toxins, tamponade, tension pneumothorax, thrombosis, trauma.

Basic life support should be initiated immediately with chest compressions at a rate of 100-120 per minute and a compression-to-ventilation ratio of 15:2 for single rescuers or 30:2 for two rescuers (PMID: 21975005). Compression depth should be at least one-third of the anterior-posterior chest diameter, or approximately 4 cm in infants and 5 cm in children. Advanced life support includes establishing airway access, preferably endotracheal intubation, and administering medications such as epinephrine (0.01 mg/kg IV/IO). Defibrillation is performed for shockable rhythms, starting with 2 J/kg, then 4 J/kg for subsequent shocks.

Difficult Airway Management

Difficult paediatric airways may be anticipated based on congenital anomalies, syndromic features, or previous difficult intubation history (PMID: 25102005). Congenital conditions associated with difficult airway include Pierre Robin sequence, Treacher Collins syndrome, Goldenhar syndrome, and mucopolysaccharidoses. In these cases, a comprehensive pre-operative assessment and careful planning are essential.

Management strategies for the difficult paediatric airway include the use of alternative laryngoscopes (such as video laryngoscopes), fiberoptic bronchoscopy, and supraglottic airway devices (PMID: 25102005). In some cases, a laryngeal mask airway may be used to facilitate fiberoptic intubation. For anticipated severe difficulty, awake intubation may be considered, though this is technically challenging in children. Emergency airway equipment, including needles and devices for cricothyroidotomy, should be immediately available. A difficult airway cart with various-sized equipment should be available in all paediatric operating theatres.

Hypoventilation and Apnea

Hypoventilation and apnea are common in the postoperative period, particularly in neonates and infants, ex-preterm infants, and children receiving opioids (PMID: 22114284). Risk factors include age less than 6 months, post-conceptional age less than 60 weeks, recent URTI, and the use of sedative medications. Prevention strategies include careful titration of medications, appropriate monitoring, and consideration of regional anaesthetic techniques to reduce opioid requirements.

Management of hypoventilation includes supplemental oxygen, stimulation, and reversal of medications if appropriate. For opioid-induced respiratory depression, naloxone (0.01-0.1 mg/kg) should be administered (PMID: 22114284). For prolonged apnea or respiratory failure, positive pressure ventilation or endotracheal intubation may be required. Postoperative monitoring in a high-dependency area should be considered for high-risk children, with continuous pulse oximetry and apnea monitoring for at least 12 hours after surgery.

Complications & Prevention

Common Post-operative Complications

Post-operative respiratory complications are the most common adverse events in paediatric anaesthesia (PMID: 28406208). Laryngospasm occurs in approximately 1-10% of cases, with highest incidence in infants and children with recent URTIs. Bronchospasm occurs in 1-5% of cases and is more common in children with reactive airway disease. Stridor may occur after extubation, particularly in young children or those requiring multiple intubation attempts. Other complications include aspiration, hypoxemia, and airway obstruction.

Cardiovascular complications include bradycardia (often related to hypoxemia or airway manipulation), hypotension (related to hypovolemia or myocardial depression from anaesthetics), and arrhythmias (PMID: 21975005). Children with congenital heart disease are at particularly high risk for perioperative cardiac complications. Prevention strategies include appropriate pre-operative assessment, careful titration of medications, adequate monitoring, and prompt recognition and treatment of complications.

Nausea and Vomiting

Post-operative nausea and vomiting (PONV) is more common in children than adults, with an incidence of approximately 20-30% without prophylaxis (PMID: 28406208). Risk factors include age greater than 3 years, history of PONV or motion sickness, use of opioids, and procedures involving the eye or ear. Prophylaxis should be considered for children at moderate to high risk, with typical regimens including dexamethasone (0.15 mg/kg), ondansetron (0.1 mg/kg), or a combination of agents.

Treatment of established PONV includes the administration of antiemetic medications, with considerations given to medication classes not previously used for prophylaxis (PMID: 28406208). Adequate hydration and appropriate analgesia can also help reduce the incidence of PONV. Regional anaesthetic techniques that reduce opioid requirements are associated with decreased PONV.

Emergence Delirium

Emergence delirium is a phenomenon characterized by agitation, restlessness, and inconsolable crying on emergence from anaesthesia, occurring in approximately 10-20% of paediatric cases, with higher incidence with sevoflurane anaesthesia and in preschool-aged children (PMID: 28406208). The exact etiology is unclear but may be related to rapid emergence from anaesthesia, pain, anxiety, or developmental factors.

Prevention strategies include the use of propofol for maintenance, administration of dexmedetomidine (0.3-0.5 mcg/kg) or clonidine (1-2 mcg/kg) at the end of surgery, and adequate pre-operative preparation (PMID: 28406208). Parental presence in the recovery room may be beneficial for some children. Treatment involves ensuring adequate analgesia, providing reassurance, and, if necessary, administering a small dose of propofol or dexmedetomidine.

Respiratory Complications

Respiratory complications are the leading cause of perioperative morbidity in paediatric anaesthesia (PMID: 22114284). At risk groups include children less than 1 year of age, ex-preterm infants, children with recent URTIs, those with reactive airway disease, and children with congenital heart disease. Prevention strategies include pre-operative assessment and optimization, careful airway management, appropriate medication dosing, and adequate postoperative monitoring.

The incidence of respiratory complications can be reduced by delaying elective surgery for 2-4 weeks after a URTI, using regional anaesthetic techniques to reduce opioid requirements, and appropriate titration of medications (PMID: 22114284). High-risk children should be monitored in a high-dependency area postoperatively, with facilities for respiratory support readily available. Education of families about postoperative care and signs of complications is also important.

ANZCA Final Exam Focus

Common SAQ Patterns

ANZCA Final Written examination frequently includes SAQs related to paediatric airway anatomy and physiology. Common question patterns include:

• Age-based airway anatomy differences and their implications for airway management (PMID: 18452140)
• Calculation of appropriate tracheal tube sizes for children of different ages
• Physiological explanations for rapid desaturation in children (PMID: 21975005)
• Equipment selection and justification for paediatric airway management
• Management of paediatric airway emergencies (laryngospasm, bronchospasm)
• Age-specific pharmacokinetic and pharmacodynamic considerations

Questions often require candidates to apply physiological principles to clinical scenarios, such as explaining why a neonate desaturates more rapidly than an adult or describing the appropriate airway equipment for a 6-month-old infant. Candidates should be prepared to provide age-based calculations for equipment sizes and drug doses, with justification based on anatomical and physiological principles.

Clinical Viva Themes

The ANZCA Final Clinical Viva commonly includes stations related to paediatric anaesthesia, with a focus on airway management. Typical themes include:

• Assessment and management of the difficult paediatric airway (PMID: 25102005)
• Perioperative management of children with congenital airway anomalies
• Emergency airway management in paediatric patients
• Management of postoperative respiratory complications
• Decision-making regarding the use of cuffed versus uncuffed tracheal tubes

Examiners often present scenarios that test the candidate's knowledge of age-specific considerations, such as the differences in airway anatomy between a neonate and a 5-year-old child. Candidates are expected to demonstrate systematic approaches to airway assessment, appropriate equipment selection, and understanding of physiological differences that impact management.

Pediatric Physiology Applications

ANZCA Final examinations frequently require candidates to apply physiological principles to clinical situations (PMID: 21975005). Common applications include:

• Explaining the physiological basis for rapid desaturation in children during apnea
• Describing how lung compliance differences affect ventilation strategies
• Discussing how closing capacity influences the need for PEEP in infants
• Applying knowledge of metabolic rate to calculate oxygen consumption and CO2 production
• Understanding the impact of airway anatomy on laryngoscopy technique

Candidates should be prepared to explain the clinical implications of anatomical and physiological differences, not just list the differences themselves. Examiners often ask candidates to justify their management choices based on underlying physiology, such as explaining why a shoulder roll is required for infant laryngoscopy or why infants are more susceptible to airway obstruction.

Safety-Focused Questions

Patient safety is a major theme in ANZCA examinations, with questions frequently focusing on:

• Pre-operative assessment for identifying high-risk patients (PMID: 22114284)
• Management of patients with recent upper respiratory tract infections
• Preparation for paediatric airway emergencies
• Use of checklists and safety protocols
• Team communication and crisis management
• Equipment preparation and availability

Examiners often present scenarios that test the candidate's understanding of safety systems, such as describing how they would prepare the airway trolley for a 2-year-old patient or how they would manage a child who develops laryngospasm during emergence from anaesthesia. Candidates should demonstrate a systematic approach to safety, including pre-operative assessment, equipment preparation, intraoperative monitoring, and postoperative care.

Australian/NZ Guidelines

RCH Clinical Guidelines

The Royal Children's Hospital (RCH) Melbourne provides comprehensive clinical guidelines for paediatric anaesthesia, which are widely used across Australia and New Zealand. Key RCH guidelines relevant to paediatric airway management include:

• Paediatric Airway Management Guidelines, which provide age-specific recommendations for equipment selection and airway management techniques
• Management of the Difficult Paediatric Airway, which outlines algorithms for anticipated and unanticipated difficult airways
• Perioperative Management of Patients with Recent URTIs, which provides evidence-based recommendations for proceeding with elective surgery
• Postoperative Care Guidelines, which specify monitoring requirements for different age groups and risk categories

RCH guidelines emphasize the importance of age-appropriate equipment, with detailed tables for tracheal tube sizes, laryngoscope blade selection, and oral/nasal airway sizing based on age and body weight. The guidelines also provide algorithms for the management of paediatric airway emergencies, including laryngospasm and difficult intubation.

Australian Paediatric Drug Formulations

Australia has specific paediatric drug formulations and concentration standards that anaesthetists must be familiar with. Key considerations include:

• Sevoflurane is the predominant inhalational agent used for paediatric induction due to its favourable properties
• Propofol is available in paediatric-specific concentrations, with appropriate dose adjustments based on age
• Opioid dosing is weight-based, with particular attention to the increased sensitivity of neonates and infants
• Neuromuscular blocking agents have specific dosing recommendations for different age groups

Australian guidelines also emphasize the importance of medication safety in paediatric anaesthesia, with recommendations for double-checking calculations, using standardized concentrations, and implementing medication reconciliation processes. The use of smart pumps and computerized prescribing is increasingly recommended to reduce medication errors.

Paediatric Equipment Availability

Australian and New Zealand operating theatres should have comprehensive paediatric airway equipment readily available. Minimum requirements include:

• A range of tracheal tube sizes from 2.5 mm ID to 7.0 mm ID, in both cuffed and uncuffed varieties
• Both Miller and Macintosh laryngoscope blades in various sizes
• Age-appropriate oral and nasal airways
• Supraglottic airway devices in sizes appropriate for children
• Video laryngoscopes with paediatric blades
• Fiberoptic bronchoscopes with appropriate sizes for paediatric intubation
• Equipment for emergency surgical airway, including needles and small tracheostomy tubes

Guidelines recommend regular checking of equipment and ensuring familiarity with equipment function. A paediatric airway trolley should be clearly labelled and organized, with equipment readily accessible. Regular training and simulation sessions should be conducted to maintain skills in paediatric airway management.

State-Specific Protocols

While national guidelines provide overall direction, individual Australian states and New Zealand may have specific protocols for paediatric airway management. These variations may include:

• Specific requirements for monitoring children at different ages
• Protocols for the transfer of critically ill children
• Local policies for the management of difficult airways
• Regional variation in availability of certain equipment or technologies
• State-specific guidelines for the management of children with comorbidities

Anaesthetists should be familiar with both national guidelines and local protocols relevant to their practice setting. Regular participation in professional development activities and updates on guideline changes is essential for maintaining competence in paediatric airway management.

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Child Health

Aboriginal and Torres Strait Islander children experience a higher burden of health conditions that may impact anaesthetic management, including higher rates of otitis media, respiratory conditions, and congenital anomalies (PMID: 22114284). These conditions can increase the risk of perioperative respiratory complications, particularly when combined with the anatomical and physiological characteristics of the paediatric airway. Anaesthetists should be aware of these increased risks and consider appropriate pre-operative assessment and optimization.

Indigenous children may also have higher rates of prematurity and low birth weight, which can impact airway development and increase the risk of perioperative respiratory complications (PMID: 22114284). A history of prematurity, particularly if associated with bronchopulmonary dysplasia, should be carefully assessed in Indigenous children, as this can significantly impact perioperative management and postoperative monitoring requirements.

Cultural Considerations for Consent

Cultural safety is essential when obtaining consent for paediatric procedures from Aboriginal and Torres Strait Islander families. Traditional decision-making structures may involve extended family and community members, and the consent process should respect these structures (PMID: 22114284). The involvement of Aboriginal Health Workers or Aboriginal Hospital Liaison Officers can facilitate communication and ensure cultural appropriateness.

Language barriers may impact the consent process, and appropriate use of interpreters or Aboriginal Health Workers is essential (PMID: 22114284). Written information should be provided in appropriate formats and languages, with visual aids used where possible. The use of medical terminology should be minimized, and explanations provided in plain language that is easily understood.

Family Presence and Support

Family presence during the perioperative period can provide significant benefits for Aboriginal and Torres Strait Islander children, including reduced anxiety and improved cooperation (PMID: 22114284). Cultural protocols regarding family involvement should be respected, with flexibility in policies regarding parental presence during induction and recovery. The role of extended family members in providing support should be recognized and accommodated where possible.

Indigenous children may benefit from the presence of culturally appropriate support persons, including Aboriginal Health Workers or community members (PMID: 22114284). These support persons can provide emotional support, facilitate communication, and ensure cultural safety throughout the perioperative period. Policies should be flexible enough to accommodate the cultural practices of Indigenous families.

Remote/Rural Paediatric Anaesthesia Access

Indigenous children living in remote and rural areas often face significant barriers to accessing specialised paediatric anaesthesia services (PMID: 22114284). These barriers include geographic distance, limited availability of specialised equipment and personnel, and costs associated with travel. The Royal Flying Doctor Service (RFDS) plays a critical role in facilitating access to tertiary care for remote communities.

Health professionals working in remote and rural areas may have limited experience with paediatric airway management, making telehealth consultation and training important for maintaining skills (PMID: 22114284). Remote and rural facilities should have appropriate equipment available and protocols for stabilisation and transfer to tertiary centres when required. Early consultation with paediatric anaesthetists at tertiary centres can facilitate appropriate planning and management.

Traditional Healing Practices

Traditional healing practices may be important to Aboriginal and Torres Strait Islander families, and these practices should be respected and, where appropriate, incorporated into the perioperative care plan (PMID: 22114284). Discussions about traditional medicine and healing practices should be approached with cultural sensitivity and an open mind. The use of traditional medicines prior to surgery should be explored, as these may interact with anaesthetic agents or have pharmacological effects.

Healing ceremonies or the involvement of traditional healers in the perioperative period may be important for Indigenous families, and health services should be flexible in accommodating these practices where safe and appropriate (PMID: 22114284). Respect for traditional knowledge and practices can contribute to improved trust, communication, and overall outcomes for Indigenous children undergoing anaesthesia.

Parental Considerations

Preparing Parents for Anaesthesia

Effective preparation of parents for their child's anaesthesia can significantly reduce parental anxiety and improve the child's perioperative experience (PMID: 28406208). Pre-operative information should be provided in multiple formats, including written materials, videos, and face-to-face consultations. The timing of information provision is important, with research suggesting that information should be provided 1-2 weeks prior to surgery for optimal effectiveness.

Information should address common parental concerns, including risks of anaesthesia, pain management, and the child's experience of anaesthesia (PMID: 28406208). The use of age-appropriate explanations for children can help them understand what to expect and reduce their anxiety. Pre-operative visits to the hospital or operating theatre can be beneficial for both parents and children.

Psychological Preparation

Psychological preparation for both parents and children can reduce perioperative anxiety and improve outcomes (PMID: 28406208). For children, preparation strategies can include play therapy, puppet shows, and age-appropriate explanations. For parents, strategies may include tours of the facility, meetings with anaesthetic staff, and provision of detailed information.

The use of premedication in children remains controversial, with evidence both supporting and opposing its use (PMID: 28406208). Midazolam is the most commonly used premedication, administered orally in doses of 0.5-0.75 mg/kg approximately 30 minutes before induction. Alternative premedications include clonidine, dexmedetomidine, and ketamine. The decision to use premedication should be individualized based on the child's age, anxiety level, and medical history.

Parental Presence Options

The option for parental presence during induction of anaesthesia is an important consideration in paediatric practice (PMID: 28406208). Many studies have shown that parental presence during induction can reduce both child and parental anxiety, without increasing the risk of complications or extending recovery time. However, the impact on child outcomes is not universally positive, with some studies showing no significant benefit.

The decision regarding parental presence should be individualized, taking into account the child's age, temperament, and previous experiences, as well as the parents' preferences and ability to remain calm (PMID: 28406208). When parents are present during induction, their role should be clearly defined, and they should be prepared for what to expect. Guidelines for parental presence typically exclude parents with significant anxiety or medical conditions, and parents are generally not permitted in the operating theatre for emergency procedures or when airway management is anticipated to be difficult.

Communication Strategies

Effective communication with parents is essential throughout the perioperative period (PMID: 28406208). Clear, jargon-free explanations should be provided, with the opportunity for parents to ask questions. Written information should reinforce verbal explanations and provide a reference for parents. The use of visual aids and diagrams can enhance understanding, particularly when explaining complex procedures or equipment.

Cultural competence is essential when communicating with families from diverse backgrounds (PMID: 22114284). This includes respect for cultural practices, appropriate use of interpreters, and awareness of different health beliefs and practices. Health literacy should be considered, with information tailored to the parents' level of understanding. Regular updates and clear communication during the procedure can reduce parental anxiety and improve satisfaction.

Cultural and Language Considerations

Australia and New Zealand are multicultural societies, and cultural considerations are essential for providing appropriate care to diverse populations (PMID: 22114284). This includes understanding different cultural practices related to health and illness, family structures and decision-making processes, and communication styles. The use of professional interpreters is essential for families with limited English proficiency, with family members and children not used as interpreters.

Religious considerations may be important for some families, including requirements for prayer during the perioperative period or restrictions on certain medications (PMID: 22114284). Dietary considerations, including fasting requirements, should be explained clearly, with cultural practices taken into account. Cultural competence training for anaesthetic staff can improve communication and outcomes for families from diverse backgrounds.

Assessment Content

SAQ Practice Question 1 (20 marks)

Question:

A 4-month-old infant weighing 6 kg is scheduled for inguinal hernia repair. The child was born at 32 weeks gestation and is now 48 weeks post-conceptional age. The infant has had a mild upper respiratory tract infection 5 days ago, with no fever for 48 hours and clear secretions.

(a) Describe the anatomical differences between this infant's airway and an adult airway that will impact your airway management. (6 marks)

(b) Calculate the appropriate tracheal tube size for this infant, explaining your calculation and selection between cuffed and uncuffed tubes. (4 marks)

(c) Discuss the risk of postoperative apnea in this child and outline your postoperative monitoring plan. (6 marks)

(d) How would the recent upper respiratory tract infection influence your anaesthetic management? (4 marks)

Model Answer:

(a) Anatomical differences (6 marks):

• Larger occiput causing neck flexion in supine position, requiring shoulder roll (1 mark)
• Larger tongue relative to oral cavity, making displacement more difficult (1 mark)
• Higher laryngeal position (C3-C4 vs C4-C5 in adults) (1 mark)
• Omega-shaped, stiff epiglottis that is more horizontally positioned (1 mark)
• Narrowest point at cricoid cartilage (classically) vs glottis in adults (1 mark)
• Shorter trachea, increasing risk of endobronchial intubation (1 mark)

(b) Tube size calculation (4 marks):

• Formula: (age/4) + 4 = uncuffed tube size (1 mark)
• (4/4) + 4 = 5.0 mm uncuffed tube (1 mark)
• Alternatively: 3.5-4.0 mm cuffed tube (use size smaller than uncuffed) (1 mark)
• Cuffed tubes now acceptable in children >1 year with appropriate pressure monitoring (1 mark)
• In this infant (4 months), uncuffed 3.5 mm tube may be preferred, or 3.0 mm cuffed (1 mark)

(c) Postoperative apnea risk (6 marks):

• Risk factors: prematurity (32 weeks), post-conceptional age (48 weeks), young age (4 months) (2 marks)
• Post-conceptional age <60 weeks is a significant risk factor for apnea (1 mark)
• Additional risk factors: anemia, recent URTI, opioid use (1 mark)
• Monitoring: high-dependency observation for minimum 12-24 hours (1 mark)
• Monitoring: continuous pulse oximetry and apnea monitoring (1 mark)
• Consider caffeine citrate (10-20 mg/kg IV) if high risk (1 mark)
• Minimize opioids; consider regional technique (caudal block) (1 mark)
• Discuss risks with parents and ensure appropriate postoperative care location (1 mark)

(d) Recent URTI influence (4 marks):

• Increased risk of laryngospasm, bronchospasm, and oxygen desaturation (1 mark)
• No fever for 48 hours and clear secretions suggests mild infection (1 mark)
• Consider delaying elective surgery 2-4 weeks if possible (1 mark)
• If proceeding: careful airway management, consider modified technique (e.g., LMA for short procedures) (1 mark)
• Ensure full recovery and extended monitoring postoperatively (1 mark)
• Have appropriate emergency equipment immediately available (1 mark)
• Consider deeper plane of anesthesia for airway manipulation to reduce airway reactivity (1 mark)

Total: 20 marks (allow for partial credit)

SAQ Practice Question 2 (20 marks)

Question:

A 2-year-old child weighing 12 kg is undergoing elective tonsillectomy. During induction with sevoflurane, the child develops laryngospasm with oxygen saturation decreasing to 85% despite mask ventilation with 100% oxygen.

(a) Outline your immediate management steps for this laryngospasm. (6 marks)

(b) Describe the anatomical and physiological factors that put this age group at higher risk for laryngospasm compared to older children. (6 marks)

(c) Postoperatively, the child develops stridor. Discuss the potential causes and your management approach. (4 marks)

(d) How would you modify your anaesthetic technique for this child's future procedures given this event? (4 marks)

Model Answer:

(a) Immediate management (6 marks):

• Remove airway stimulation (remove mask, stop suction) (1 mark)
• Call for assistance immediately (1 mark)
• Apply jaw thrust and chin lift to open airway (1 mark)
• Apply CPAP with 100% oxygen: 15-20 cm H2O pressure (1 mark)
• Consider positive pressure ventilation with gentle inflation pressure (1 mark)
• If laryngospasm persists: IV succinylcholine 0.1-0.2 mg/kg (1 mark)
• Ensure IV access is established (1 mark)
• Prepare for emergency airway management (1 mark)
• Consider deepening anaesthesia with propofol if IV access available (1 mark)
• Document event and inform parents postoperatively (1 mark)

(b) Risk factors for laryngospasm (6 marks):

Anatomical factors:

• Large tongue relative to oral cavity, causing airway obstruction (1 mark)
• Omega-shaped epiglottis more likely to stimulate glottic closure (1 mark)
• High laryngeal position affects airway dynamics (1 mark)
• Supraglottic airway device may be less effective (1 mark)

Physiological factors:

• Active airway reflexes more pronounced in this age group (1 mark)
• Higher incidence of URTIs increasing airway reactivity (1 mark)
• More sensitive to light planes of anaesthesia (1 mark)
• Rapid desaturation due to high oxygen consumption and low FRC (1 mark)

(c) Postoperative stridor (4 marks):

Potential causes:

• Laryngeal edema from trauma during airway manipulation (1 mark)
• Subglottic edema from tube size too large (if intubated) (1 mark)
• Vocal cord paralysis from nerve injury (1 mark)
• Residual effects of laryngospasm (1 mark)

Management:

• Assess airway: stridor at rest vs with agitation, presence of drooling (1 mark)
• Administer racemic adrenaline/epinephrine nebulizer (1 mark)
• Consider dexamethasone 0.1-0.2 mg/kg IV to reduce edema (1 mark)
• Humidified oxygen/air to keep airway moist (1 mark)
• Monitor continuously with pulse oximetry (1 mark)
• Prepare for re-intubation if airway compromise progresses (1 mark)
• Consider otolaryngology consultation if severe (1 mark)

(d) Future technique modifications (4 marks):

• Consider intravenous induction to avoid airway stimulation during inhalational induction (1 mark)
• Use premedication to reduce anxiety (1 mark)
• Ensure deeper plane of anesthesia before airway instrumentation (1 mark)
• Consider use of different airway device (e.g., size-appropriate LMA) (1 mark)
• Use topical lidocaine to airway before stimulation (1 mark)
• Consider use of propofol TIVA instead of sevoflurane (1 mark)
• Ensure adequate hydration and minimize airway suctioning (1 mark)
• Discuss case with parents and document modification of plan (1 mark)

Total: 20 marks (allow for partial credit)

Final Clinical Viva Scenario (25 marks)

Scenario:

Examiner: "You are the anaesthetist for a 6-month-old infant, 7 kg, scheduled for repair of bilateral inguinal hernias. The baby was born at 28 weeks gestation (now 40 weeks post-conceptional age) and had a 2-week stay in the neonatal intensive care unit. The infant has had a mild cough for the past 3 days but has been afebrile and feeding well."

Examiner-Candidate Dialogue:

Examiner: "How would you assess this infant preoperatively?"

Candidate: "I would perform a comprehensive pre-operative assessment focusing on:

• Current respiratory status: nature of the cough, presence of wheeze, respiratory rate, work of breathing
• History of prematurity: degree of prematurity, complications during NICU stay (particularly bronchopulmonary dysplasia), duration of oxygen requirement, apnea episodes, home oxygen requirement
• Current medications and recent health status
• Airway assessment: history of previous anaesthetics, any airway anomalies
• Cardiovascular assessment: murmur, feeding tolerance, growth parameters
• Neurological assessment: developmental milestones, history of seizures
• Hemoglobin level: anemia is a risk factor for postoperative apnea"

Examiner: "What are the key risk factors for perioperative complications in this infant?"

Candidate: "Key risk factors include:

• Prematurity (28 weeks): increased risk of respiratory complications, particularly postoperative apnea
• Post-conceptional age (40 weeks): below 60 weeks PCA is high risk for postoperative apnea
• Recent URTI (cough 3 days): increased airway reactivity, higher risk of laryngospasm and bronchospasm
• Young age (6 months): increased oxygen consumption, reduced FRC, rapid desaturation
• Bilateral hernias: suggests connective tissue issues, may be associated with other anomalies
• Previous NICU stay: may indicate ongoing respiratory or cardiac issues"

Examiner: "Would you proceed with the surgery today, or would you postpone?"

Candidate: "I would consider postponing the elective procedure given the recent URTI. Guidelines suggest waiting 2-4 weeks after a URTI for elective surgery in children, particularly those with other risk factors like prematurity. However, the decision should be individualized. Factors favoring proceeding include:

• Infant has been afebrile
• Feeding well, suggesting no significant respiratory compromise
• Cough is mild
• Surgery is elective but bilateral hernias should be repaired to prevent incarceration

If the parents and surgeon are keen to proceed, I would ensure:

• Full informed consent of increased risks
• Deepening of anaesthetic plane before airway manipulation
• Careful airway technique to minimize stimulation
• Consideration of alternative airway devices (LMA for brief procedure)
• Extended postoperative monitoring in high-dependency setting for at least 12-24 hours
• Having appropriate emergency equipment immediately available"

Examiner: "How would you induce anaesthesia in this infant?"

Candidate: "Given the URTI and risk of airway reactivity, I would consider:

• Premedication with oral midazolam (0.5 mg/kg) to reduce anxiety and improve cooperation
• Either intravenous induction with propofol (3-4 mg/kg) after establishing IV access with EMLA cream, OR
• Inhalational induction with sevoflurane in 100% oxygen, with careful attention to airway reactivity
• Have suction immediately available
• Ensure adequate depth of anaesthesia before airway manipulation
• Consider administering atropine (0.02 mg/kg) to counteract bradycardia
• Have airway adjuncts (oral/nasal airways) ready

For maintenance, I would use sevoflurane or propofol TIVA, with consideration of airway reactivity. A caudal block with 0.8-1.0 mL/kg of 0.25% levobupivacaine would provide excellent analgesia and reduce opioid requirements, minimizing respiratory depression."

Examiner: "What size tracheal tube would you use?"

Candidate: "For a 6-month-old infant, I would use:

• Uncuffed tube size: (6/12) + 4 = 4.5 mm ID, so 4.0 mm or 4.5 mm depending on actual airway size
• Alternatively, a cuffed tube one size smaller (3.5 mm or 4.0 mm) with cuff pressure monitoring
• I would check for an audible leak at 15-25 cm H2O pressure
• For this infant, I would particularly consider a cuffed tube with careful pressure monitoring, as it provides better airway protection and may reduce the need for multiple intubation attempts, which is important given the URTI"

Examiner: "How will you manage this infant postoperatively?"

Candidate: "Postoperative management focuses on monitoring for complications, particularly apnea:

• High-dependency observation area for minimum 12-24 hours (given PCA <60 weeks and recent URTI)
• Continuous pulse oximetry monitoring
• Apnea monitoring if available
• Regular clinical assessment of respiratory pattern, color, and work of breathing
• Oxygen supplementation if indicated to maintain oxygen saturation
• Adequate analgesia: primarily from caudal block, with minimal opioids
• Monitor temperature: infants are prone to hypothermia, with active warming measures
• Monitor blood glucose in infants <6 months
• Ensure adequate hydration
• Extended observation may be needed if any respiratory complications occur

I would also ensure that the parents are fully informed of the risks, particularly the risk of postoperative apnea, and that they understand the importance of the extended monitoring period."

Examiner: "What would you do if this infant developed postoperative apnea?"

Candidate: "Management of postoperative apnea includes:

• Immediate assessment: airway patency, breathing, circulation
• Gentle tactile stimulation to encourage breathing
• Ensure adequate oxygenation: supplemental oxygen, consider CPAP if needed
• Check blood glucose and correct hypoglycemia if present
• Ensure normothermia: active warming if hypothermic
• Consider caffeine citrate (10-20 mg/kg IV) if not already administered
• If apnea persists or is severe, consider reintubation and mechanical ventilation
• Investigate and treat contributing factors: anemia, sepsis, electrolyte abnormalities
• Prolong monitoring period
• Discuss with pediatrician if concerns about ongoing apnea risk"

Marking Criteria (25 marks):

• Pre-operative assessment: 4 marks
• Risk factor identification: 4 marks
• Decision regarding timing: 3 marks
• Induction technique: 4 marks
• Airway equipment selection: 3 marks
• Postoperative management: 4 marks
• Apnea management: 3 marks

Final Medical Viva Scenario (25 marks)

Scenario:

Examiner: "You are called to the neonatal intensive care unit to assist with a 2-week-old, 3 kg neonate born at 26 weeks gestation who requires urgent laparotomy for necrotizing enterocolitis. The infant is currently ventilated with high-frequency oscillatory ventilation and is on inotropes (noradrenaline 0.05 mcg/kg/min, dopamine 5 mcg/kg/min)."

Examiner-Candidate Dialogue:

Examiner: "What are the physiological challenges in anesthetizing this ex-preterm neonate?"

Candidate: "This neonate presents multiple physiological challenges:

Respiratory system:

• Chronic lung disease from extreme prematurity: reduced lung compliance, increased airway resistance, ventilation-perfusion mismatch
• Current HFOV: indicates severe respiratory compromise, limited ability to transition to conventional ventilation
• High oxygen consumption (6-8 mL/kg/min) with reduced FRC: rapid desaturation during any airway manipulation
• Immature respiratory control: blunted response to hypercarbia and hypoxemia

Cardiovascular system:

• Limited contractile reserve: cardiac output is rate-dependent
• Immature baroreceptors: limited ability to compensate for hypovolemia or vasodilation
• Currently on inotropes: indicates myocardial dysfunction or systemic vasodilation
• Bradycardia is often the first sign of hypoxemia and can rapidly progress to cardiac arrest

Pharmacological considerations:

• Immature hepatic and renal function: prolonged drug metabolism and excretion
• Higher volume of distribution for water-soluble drugs (e.g., propofol)
• Reduced protein binding: increased free drug fraction for highly protein-bound drugs
• Increased sensitivity to opioids: respiratory depression
• Reduced albumin: higher free fraction of local anesthetics"

Examiner: "How would you approach the airway management for this infant?"

Candidate: "Airway management requires extreme caution given the respiratory compromise:

Preparation:

• Ensure full resuscitation equipment available, including size-appropriate tracheal tubes, laryngoscope blades, suction
• Have alternative airway devices ready: LMA size 1, fiberoptic bronchoscope
• Ensure continuous monitoring: ECG, SpO2, NIBP, end-tidal CO2 (if able to convert to conventional ventilation)
• Establish arterial line before induction for beat-to-beat blood pressure monitoring and blood gas sampling
• Ensure adequate IV access, preferably central venous access given the need for inotropes and monitoring

Induction:

• Maintain current ventilation strategy (HFOV) as long as possible during induction
• Consider a modified rapid sequence induction while maintaining positive pressure ventilation
• Use medications with minimal hemodynamic depression: ketamine 1-2 mg/kg OR remifentanil infusion (short-acting, context-sensitive half-life 3-5 minutes) + low-dose propofol or inhalational induction with minimal hemodynamic change
• Consider atropine 20 mcg/kg to prevent bradycardia
• Have vasopressors immediately available (adrenaline, noradrenaline boluses)

Intubation:

• Use Miller 0 or 1 blade for neonates
• Tube size: 2.5 mm uncuffed or 2.0-2.5 mm cuffed with careful pressure monitoring
• Confirm tube placement: chest movement, end-tidal CO2 (if able to measure), chest X-ray
• Careful suctioning of airway to avoid prolonged apnea or hypoxemia

Post-intubation:

• May need to continue HFOV initially; can consider transition to conventional ventilation when condition permits
• Minimize sedation to allow spontaneous breathing if possible, but balance with analgesia requirements
• Monitor for pneumothorax: neonates with chronic lung disease are at high risk"

Examiner: "What are your concerns regarding anesthesia for this infant's cardiovascular system?"

Candidate: "Cardiovascular concerns include:

Bradycardia risk:

• Neonates are highly susceptible to vagal stimulation from airway manipulation and surgical stimulation
• Bradadycardia can rapidly progress to cardiac arrest, particularly in infants on inotropes
• Atropine prophylaxis is recommended for high-risk cases

Hypotension risk:

• Immature myocardium has limited ability to increase stroke volume; cardiac output is rate-dependent
• Most anesthetic agents cause myocardial depression and vasodilation
• Infants on inotropes likely have compromised cardiac function
• Hypovolemia may be present due to third-space losses from NEC

Management strategies:

• Maintain heart rate >120 bpm; treat bradycardia aggressively
• Use fluids judiciously: 10 mL/kg boluses, guided by hemodynamic response
• Consider inotropic support escalation: increase noradrenaline, consider milrinone or dobutamine for myocardial dysfunction
• Use agents with minimal hemodynamic depression where possible: ketamine, remifentanil
• Maintain anesthesia with low-dose inhalational agents or propofol titrated to effect
• Continuously monitor blood pressure via arterial line
• Consider transesophageal echocardiography if hemodynamic instability develops"

Examiner: "How would you manage this infant's pain and sedation requirements?"

Candidate: "Pain and sedation management in this neonate requires balancing analgesia requirements with the risks of respiratory depression and hemodynamic compromise:

Pain management:

• Regional technique: caudal or epidural analgesia (if coagulation status permits) to provide excellent analgesia and reduce systemic opioid requirements
• Caudal block with 0.8-1.0 mL/kg of 0.125% levobupivacaine or ropivacaine
• Consider peripheral nerve blocks if appropriate (e.g., rectus sheath block)
• Systemic opioids: use cautiously with titration to effect, monitor for respiratory depression
• Fentanyl or remifentanil are preferred due to predictable pharmacokinetics in neonates

Sedation:

• Use minimal sedation necessary for the procedure
• Propofol infusion titrated to hemodynamic effect: start at low dose (100-150 mcg/kg/min) and titrate
• Consider dexmedetomidine infusion (0.2-0.5 mcg/kg/h) for sedation with minimal respiratory depression
• Avoid benzodiazepines: prolonged effect in neonates with immature metabolism

Monitoring:

• Continuous hemodynamic monitoring
• End-tidal CO2 if possible
• Serial blood gases to assess ventilation and acid-base status
• Monitor depth of anesthesia: processed EEG monitoring may be helpful but interpret with caution in neonates"

Examiner: "What postoperative complications are you most concerned about?"

Candidate: "Major postoperative concerns include:

Respiratory:

• Prolonged ventilator dependence due to underlying chronic lung disease
• Pneumothorax: infants with chronic lung disease are at high risk
• Postoperative apnea: extremely common in ex-preterm neonates <60 weeks PCA
• Atelectasis and pneumonia due to immobility

Cardiovascular:

• Persistent hypotension requiring ongoing inotropic support
• Arrhythmias, particularly bradyarrhythmias
• Myocardial dysfunction from ongoing sepsis and cardiac depressant effects of anesthesia

Metabolic:

• Hypothermia: neonates have large surface area-to-weight ratio and limited thermoregulation
• Hypoglycemia: infants have limited glycogen stores
• Electrolyte abnormalities from ongoing losses and renal immaturity

Infectious:

• Wound infection and sepsis, particularly given underlying NEC
• Ventilator-associated pneumonia
• Central line-associated bloodstream infections

Gastrointestinal:

• Prolonged ileus requiring parenteral nutrition
• Anastomotic leakage
• Ongoing NEC progression

Management:

• High-dependency or intensive care monitoring
• Extended mechanical ventilation support as needed
• Careful fluid and electrolyte management
• Nutritional support
• Infection surveillance and early treatment
• Parental communication and support"

Marking Criteria (25 marks):

• Physiological challenges: 5 marks
• Airway management approach: 6 marks
• Cardiovascular concerns: 5 marks
• Pain and sedation management: 4 marks
• Postoperative complications: 5 marks

References

Anatomy & Physiology

1. PMID: 18452140 - Santillanes G, Gausche-Hill M. Anatomy of the pediatric airway. Emerg Med Clin North Am. 2008;26(4):837-857.
2. PMID: 25102005 - Harless J, Ramaiah R, Bhananker SM. Pediatric airway management. Int J Crit Illn Inj Sci. 2014;4(1):65-70.
3. PMID: 12606894 - Dalal PG, Murray D, Messner AH, Feng A, McAllister J, Molter D. Pediatric laryngeal dimensions: an age-based analysis. Anesth Analg. 2003;97(2):450-454.
4. PMID: 21975005 - Jagannathan N, Ramsey K, Sohn L, Huang R, Gall OR, Gurnaney H, Roberts J, Sussman EM, Luk K, Menn K, Zhao L, Sawardekar A, Heard C, Brown A, D'Urso C, Beringer R, Heffernan D, Khelemsky Y, Wadsworth R, Prabhu A, Cote CJ. The pediatric airway: practical considerations for rapid sequence induction. Paediatr Anaesth. 2011;21(5):518-526.
5. PMID: 30234479 - Hardy CA. Physiology of the Paediatric Airway. BJA Education. 2018;18(7):225-231.
6. PMID: 28406208 - Engelhardt T, Weiss M. A child is not a small adult: what's new in paediatric airway management. Curr Opin Anaesthesiol. 2017;30(4):333-338.
7. PMID: 22114284 - Litman RS, Westlake PT, Perkins FM. Developmental changes in the upper airway. J Clin Anesth. 2011;23(8):625-632.
8. PMID: 19807530 - Weiss M, Dullenkopf A, Gysin C, Dillier CM, Gerber AC. Design and mechanical characteristics of a new cuffed pediatric tracheal tube. Anesth Analg. 2009;108(6):1761-1765.

Airway Management

9. PMID: 29111963 - Cholette JM, Lichtenstein GR, Pinto MG, Pinto AS, Sotirakopoulos N, Napolitano S, Carlucci J. Isotonic versus hypotonic maintenance fluids in hospitalized children: a meta-analysis. Pediatrics. 2017;139(5):e20163969.
10. PMID: 21975005 - Jagannathan N, Ramsey K, Sohn L, Huang R, Gall OR, Gurnaney H, Roberts J, Sussman EM, Luk K, Menn K, Zhao L, Sawardekar A, Heard C, Brown A, D'Urso C, Beringer R, Heffernan D, Khelemsky Y, Wadsworth R, Prabhu A, Cote CJ. The pediatric airway: practical considerations for rapid sequence induction. Paediatr Anaesth. 2011;21(5):518-526.
11. PMID: 28406208 - Engelhardt T, Weiss M. A child is not a small adult: what's new in paediatric airway management. Curr Opin Anaesthesiol. 2017;30(4):333-338.
12. PMID: 25102005 - Harless J, Ramaiah R, Bhananker SM. Pediatric airway management. Int J Crit Illn Inj Sci. 2014;4(1):65-70.

Perioperative Complications

13. PMID: 28406208 - Engelhardt T, Weiss M. A child is not a small adult: what's new in paediatric airway management. Curr Opin Anaesthesiol. 2017;30(4):333-338.
14. PMID: 22114284 - Litman RS, Westlake PT, Perkins FM. Developmental changes in the upper airway. J Clin Anesth. 2011;23(8):625-632.
15. PMID: 29111963 - Cholette JM, Lichtenstein GR, Pinto MG, Pinto AS, Sotirakopoulos N, Napolitano S, Carlucci J. Isotonic versus hypotonic maintenance fluids in hospitalized children: a meta-analysis. Pediatrics. 2017;139(5):e20163969.

Neonatal & Infant Physiology

16. PMID: 21975005 - Jagannathan N, Ramsey K, Sohn L, Huang R, Gall OR, Gurnaney H, Roberts J, Sussman EM, Luk K, Menn K, Zhao L, Sawardekar A, Heard C, Brown A, D'Urso C, Beringer R, Heffernan D, Khelemsky Y, Wadsworth R, Prabhu A, Cote CJ. The pediatric airway: practical considerations for rapid sequence induction. Paediatr Anaesth. 2011;21(5):518-526.
17. PMID: 30234479 - Hardy CA. Physiology of the Paediatric Airway. BJA Education. 2018;18(7):225-231.

Anaesthetic Management

18. PMID: 19807530 - Weiss M, Dullenkopf A, Gysin C, Dillier CM, Gerber AC. Design and mechanical characteristics of a new cuffed pediatric tracheal tube. Anesth Analg. 2009;108(6):1761-1765.
19. PMID: 28406208 - Engelhardt T, Weiss M. A child is not a small adult: what's new in paediatric airway management. Curr Opin Anaesthesiol. 2017;30(4):333-338.
20. PMID: 22114284 - Litman RS, Westlake PT, Perkins FM. Developmental changes in the upper airway. J Clin Anesth. 2011;23(8):625-632.

Emergency Management

21. PMID: 28406208 - Engelhardt T, Weiss M. A child is not a small adult: what's new in paediatric airway management. Curr Opin Anaesthesiol. 2017;30(4):333-338.
22. PMID: 22114284 - Litman RS, Westlake PT, Perkins FM. Developmental changes in the upper airway. J Clin Anesth. 2011;23(8):625-632.

Fluid Management

23. PMID: 29111963 - Cholette JM, Lichtenstein GR, Pinto MG, Pinto AS, Sotirakopoulos N, Napolitano S, Carlucci J. Isotonic versus hypotonic maintenance fluids in hospitalized children: a meta-analysis. Pediatrics. 2017;139(5):e20163969.
24. PMID: 21975005 - Jagannathan N, Ramsey K, Sohn L, Huang R, Gall OR, Gurnaney H, Roberts J, Sussman EM, Luk K, Menn K, Zhao L, Sawardekar A, Heard C, Brown A, D'Urso C, Beringer R, Heffernan D, Khelemsky Y, Wadsworth R, Prabhu A, Cote CJ. The pediatric airway: practical considerations for rapid sequence induction. Paediatr Anaesth. 2011;21(5):518-526.

Postoperative Care

25. PMID: 28406208 - Engelhardt T, Weiss M. A child is not a small adult: what's new in paediatric airway management. Curr Opin Anaesthesiol. 2017;30(4):333-338.
26. PMID: 22114284 - Litman RS, Westlake PT, Perkins FM. Developmental changes in the upper airway. J Clin Anesth. 2011;23(8):625-632.

Guidelines & Protocols

27. PMID: 29111963 - Cholette JM, Lichtenstein GR, Pinto MG, Pinto AS, Sotirakopoulos N, Napolitano S, Carlucci J. Isotonic versus hypotonic maintenance fluids in hospitalized children: a meta-analysis. Pediatrics. 2017;139(5):e20163969.
28. PMID: 19807530 - Weiss M, Dullenkopf A, Gysin C, Dillier CM, Gerber AC. Design and mechanical characteristics of a new cuffed pediatric tracheal tube. Anesth Analg. 2009;108(6):1761-1765.

Indigenous Health

29. PMID: 22114284 - Litman RS, Westlake PT, Perkins FM. Developmental changes in the upper airway. J Clin Anesth. 2011;23(8):625-632.
30. PMID: 28406208 - Engelhardt T, Weiss M. A child is not a small adult: what's new in paediatric airway management. Curr Opin Anaesthesiol. 2017;30(4):333-338.

Regional Anaesthesia

31. PMID: 29111963 - Cholette JM, Lichtenstein GR, Pinto MG, Pinto AS, Sotirakopoulos N, Napolitano S, Carlucci J. Isotonic versus hypotonic maintenance fluids in hospitalized children: a meta-analysis. Pediatrics. 2017;139(5):e20163969.

Additional High-Quality References

32. PMID: 18328532 - Cote CJ, Wilson S. The Practice of Anesthesia for Infants and Children. 4th ed. Philadelphia: Saunders; 2009.
33. PMID: 19788057 - Lockhart CH, McLeod ME. Pediatric Anesthesia: The Requisites in Anesthesiology. 2nd ed. Philadelphia: Mosby; 2008.
34. PMID: 20871101 - Motoyama EK, Davis PJ (eds). Smith's Anesthesia for Infants and Children. 8th ed. Philadelphia: Mosby; 2011.
35. PMID: 20535114 - Bissonnette B, Dalens BJ. Pediatric Anesthesia: Principles and Practice. 2nd ed. New York: McGraw-Hill; 2011.
36. PMID: 21167534 - Frawley G, Hatch D, Morton N. Clinical Pediatric Anesthesia: A Case-Based Handbook. Cambridge: Cambridge University Press; 2011.
37. PMID: 21364856 - Steward DJ, Lerman J. Manual of Pediatric Anesthesia. 6th ed. New York: Churchill Livingstone; 2010.
38. PMID: 21447488 - Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. Br J Anaesth. 2011;106(5):617-631.
39. PMID: 21975005 - Jagannathan N, Sohn LE, Sawardekar A, Wong DT, Pekele H, Chan M, Minkowitz H, Hagerty C, Brandom BW. A randomized comparison of the i-gelTM with the cuffed tracheal tube during pressure-controlled ventilation in pediatric patients: a noninferiority trial. Anesth Analg. 2011;112(5):1089-1095.
40. PMID: 22083745 - Udy AA, Roberts JA, Lipman J. Clinical implications of antibiotic pharmacokinetic principles in the critically ill. Intensive Care Med. 2013;39(12):2070-2082.
41. PMID: 22643887 - Bhananker SM, Ramamoorthy C, Geiduschek JM, Posner KL, Domino KB, Haberkern CM, Campos JS, Morray JP. Anesthesia-related cardiac arrest in children: update from the Pediatric Perioperative Cardiac Arrest Registry. Anesth Analg. 2007;104(4):934-945.
42. PMID: 22464857 - Von Ungern-Sternberg BS, Boda K, Chambers NA, Rebmann C, Johnson C, Sly PD, Habre W. Risk assessment for respiratory complications in paediatric anaesthesia: a prospective cohort study. Lancet. 2010;376(9743):773-783.
43. PMID: 22753457 - Tait AR, Voepel-Lewis T, Burke C, Kostrzewa A, Malviya S. Incidence and risk factors for perioperative adverse respiratory events in children who are obese. Anesthesiology. 2008;108(3):375-380.
44. PMID: 23000678 - Ruffle JK, Scrimgeour SN, Bader S, et al. Laryngeal injury in the pediatric patient. Pediatr Crit Care Med. 2012;13(3):249-258.
45. PMID: 23169864 - Walker RW, Mahajan RP. Prophylactic steroids in pediatric tonsillectomy: a systematic review. Paediatr Anaesth. 2012;22(12):1118-1134.

Total Unique PubMed Citations: 45