paediatric airways

1. Paediatric Airways Circles � airways (cricoid, trachea, bronchi, alveoli), vessels, nerves . . . Something corny � the �Rings of life�Circles � airways (cricoid, trachea, bronchi, alveoli), vessels, nerves . . . Something corny � the �Rings of life�

2. Upper Airway Anatomy Large head Large tongue High anterior larynx Infant epiglottis long, floppy & U shaped Funnel shaped larynx Narrow trachea Upper Airway Anatomy Large head with prominent occiput tends to flex the short neck and obstruct the airway � pad under shoulders in infants without pillow, no pillow for young children Large tongue increases likelihood of obstruction and may make laryngoscopy harder � often need OPA in infants and young children, don�t push your fingers under the mandible Higher anteriorly inclined larynx makes laryngoscopy harder � backward pressure usually helps Infant epiglottis long, floppy, U shaped and angled backwards (adult more in line with trachea) straight blade usually easier in infants � used under the epiglottis to lift it up Funnel shaped larynx � narrowest point at cricoid cartilage � circular cross section Neonatal trachea only 6mm diameter, 14mm in adults - tracheal length correlates better with body weight than age � tip of ETT should be 2cm past vocal cords (mid trachea � helps to avoid hitting carina on head flexion or extubating with head extension) Upper Airway Anatomy Large head with prominent occiput tends to flex the short neck and obstruct the airway � pad under shoulders in infants without pillow, no pillow for young children Large tongue increases likelihood of obstruction and may make laryngoscopy harder � often need OPA in infants and young children, don�t push your fingers under the mandible Higher anteriorly inclined larynx makes laryngoscopy harder � backward pressure usually helps Infant epiglottis long, floppy, U shaped and angled backwards (adult more in line with trachea) straight blade usually easier in infants � used under the epiglottis to lift it up Funnel shaped larynx � narrowest point at cricoid cartilage � circular cross section Neonatal trachea only 6mm diameter, 14mm in adults - tracheal length correlates better with body weight than age � tip of ETT should be 2cm past vocal cords (mid trachea � helps to avoid hitting carina on head flexion or extubating with head extension)

3. Airway Differences (just point)(just point)

4. Note how anterior and high the larynx is, imagine pushing larynx back during laryngoscopyNote how anterior and high the larynx is, imagine pushing larynx back during laryngoscopy

5. Note location of larynx and epiglottisNote location of larynx and epiglottis

6. Note potential for Guedel airway to hit epiglottis Length � incisors to angle of mandible Nasopharyngeal may work better and avoid epiglottis � use cut down ETTs if needed (don�t lose them) nose to tragus length ? Cophenylcaine forte Note potential for Guedel airway to hit epiglottis Length � incisors to angle of mandible Nasopharyngeal may work better and avoid epiglottis � use cut down ETTs if needed (don�t lose them) nose to tragus length ? Cophenylcaine forte

7. Respiratory Physiology Not mature until 8 years Deadspace volume very small Higher airflow resistance Higher chest wall compliance Higher ventilation-perfusion mismatch Higher oxygen consumption for weight Infant diaphragms lack slow muscle fibres Decreased respiratory reserve RESPIRATORY PHYSIOLOGY (Alveoli increasing in number and size from 8m2 to 70m2) Deadspace very small � adding to it greatly decreases alveolar ventilation � low volume facemasks - Rendell Baker, low volume filters Higher resistance to airflow � resistance (and therefore flow) is proportional to 4th power of the radius Chest wall 5 time more compliant in infants � little countertraction to elastic recoil of the lungs - lower lung volume and airway closure at end expiration (not until 6 years of age is the closing volume the same as FRC) (cf obesity pushing on chest wall and diaphragm) - therefore higher V/Q mismatch FRC further reduced by muscle relaxation and diaphragm splinting in GA Infants have twice the O2 consumption Infant diaphragms lack type 1 (slow) muscle fibres � fatigue much more easily End result � decreased respiratory reserve � a bit like the morbidly obese adult RESPIRATORY PHYSIOLOGY (Alveoli increasing in number and size from 8m2 to 70m2) Deadspace very small � adding to it greatly decreases alveolar ventilation � low volume facemasks - Rendell Baker, low volume filters Higher resistance to airflow � resistance (and therefore flow) is proportional to 4th power of the radius Chest wall 5 time more compliant in infants � little countertraction to elastic recoil of the lungs - lower lung volume and airway closure at end expiration (not until 6 years of age is the closing volume the same as FRC) (cf obesity pushing on chest wall and diaphragm) - therefore higher V/Q mismatch FRC further reduced by muscle relaxation and diaphragm splinting in GA Infants have twice the O2 consumption Infant diaphragms lack type 1 (slow) muscle fibres � fatigue much more easily End result � decreased respiratory reserve � a bit like the morbidly obese adult

8. Area difference = 12 fold prior to pathology Flow difference = 120 fold prior to pathology Flow ? r 4 = 400 fold following pathology Pre and post oedema differences. Area difference = 12 fold prior to pathology Flow difference = 120 fold prior to pathology Flow ? r 4 = 400 fold following pathologyPre and post oedema differences. Area difference = 12 fold prior to pathology Flow difference = 120 fold prior to pathology Flow ? r 4 = 400 fold following pathology

9. Down Syndrome Relatively large tongue Small mandible Possible Cx spine instability OSA is common Possibly smaller ETT Difficult intubation Down syndrome illustrates some of the concerns in airway assessment Relatively large tongue Small mandible Possible atlanto-axial instability � up to 20% OSA is common Possibly smaller tube than predicted due to small subglottic diameter Difficult intubation Down syndrome illustrates some of the concerns in airway assessment Relatively large tongue Small mandible Possible atlanto-axial instability � up to 20% OSA is common Possibly smaller tube than predicted due to small subglottic diameter Difficult intubation

10. Pierre Robin Syndrome Pierre Robin Syndrome highlights the small jaw � small mouth, large tongue, mandibular anomaly Other syndromes are usually really obvious and will make everyone anxious There is a condition called �Klippel-Feil� with cervical vertebral fusion � clinically short neck and limited neck movement may have other abnormalities � possibly undiagnosed Pierre Robin Syndrome highlights the small jaw � small mouth, large tongue, mandibular anomaly Other syndromes are usually really obvious and will make everyone anxious There is a condition called �Klippel-Feil� with cervical vertebral fusion � clinically short neck and limited neck movement may have other abnormalities � possibly undiagnosed

11. URTI Bronchospasm Mucous plugging ? Early pneumonia Laryngospasm Stridor Cough Bronchospasm Mucous plugging ? Early or resolving pneumonia Laryngospasm Stridor - ? Croup Cough may affect surgery Afebrile, minimally productive cough, well looking, wheeze free, Bronchospasm Mucous plugging ? Early or resolving pneumonia Laryngospasm Stridor - ? Croup Cough may affect surgery Afebrile, minimally productive cough, well looking, wheeze free,

12. Tracheal Intubation Airway protection Facilitates access to shared airway Muscle relaxation Improve efficiency of ventilation Long procedures Tracheal Intubation Airway protection � full stomach, dental work etc. Facilitates access to shared airway Muscle relaxation for surgery Improve efficiency of ventilation � PEEP increases FRC and improves V/Q mismatch Long procedures where airway closure, fatigue, and maintaining airway patency would be a problem See diagram for alignment of oral, pharyngeal and laryngeal axes See diagram for Grade of intubation Tracheal Intubation Airway protection � full stomach, dental work etc. Facilitates access to shared airway Muscle relaxation for surgery Improve efficiency of ventilation � PEEP increases FRC and improves V/Q mismatch Long procedures where airway closure, fatigue, and maintaining airway patency would be a problem See diagram for alignment of oral, pharyngeal and laryngeal axes See diagram for Grade of intubation

13. ETT Diameter Oral ETT age/4 + 4 Neonate 3.0-3.5mm Nasal under 6 years same, over 6 years half to one size smaller Length Oral ETT age/2 + 12 Nasal ETT age/2 + 15 ETT Diameter for over 1 year Neonate 3.0-3.5mm oral ETT age/4 + 4 - or 4.5 � around one fifth need a different size than what was chosen � size up or down Nasal under 6 years same, over 6 years half to one size smaller � 0.5-1.0mm smaller Length � these are the formulae for over 1 year of age � I insert the tube under vision using the black line and listen and note the length at the gums/teeth Oral ETT age/2 + 12 Nasal ETT age/2 + 15 Oral RAE for oral surgery � more easily gets the tube out of the way Infants (weight in kg): oral: 8 + (1/2)(weight)nasal: 9 + (1/2)(weight) � we are not doing under 6 months as a policy, and in practice try to stay over 12 months. Therefore I intubate more infants and neonates in uncontrolled situations than OT where I know their weight. ETT Diameter for over 1 year Neonate 3.0-3.5mm oral ETT age/4 + 4 - or 4.5 � around one fifth need a different size than what was chosen � size up or down Nasal under 6 years same, over 6 years half to one size smaller � 0.5-1.0mm smaller Length � these are the formulae for over 1 year of age � I insert the tube under vision using the black line and listen and note the length at the gums/teeth Oral ETT age/2 + 12 Nasal ETT age/2 + 15 Oral RAE for oral surgery � more easily gets the tube out of the way Infants (weight in kg): oral: 8 + (1/2)(weight)nasal: 9 + (1/2)(weight) � we are not doing under 6 months as a policy, and in practice try to stay over 12 months. Therefore I intubate more infants and neonates in uncontrolled situations than OT where I know their weight.

14. Cuffed ETT ? Postintubation croup? Recent studies little difference 2-3% cuffed or uncuffed post surgery 15% cuffed or uncuffed post PICU Less need to replace tube Better airway protection ? relevance No gas leak � good for staff and IPPV Smaller diameter tube � higher resistance Cuffed ETT? Postintubation croup? Absence of a leak at 25cm H2O in a study 1974 taken to be associated with postintubation croup - biggest problem is in under 4 yo due to airway diameter, and frequent changes of head position Recent studies little difference for the correlation between presence or absence of leak and the severity of post intubation croup 2-3% cuffed or uncuffed post surgery 15% cuffed or uncuffed post PICU regardless of leak or duration of intubation (6-10% same in various age groups in a 2004 study of 600 children under 5) Less need to replace tube (around 20% in some studies) - ? Less but tube too small, or accept brief high pressure leak Better airway protection ? relevance No gas leak � good for staff and IPPV Smaller diameter tube � higher resistance ? Subglottic (tracheal) stenosis as an outcome measure � not all studies designed to pick it up. Still using uncuffed for young childrenCuffed ETT? Postintubation croup? Absence of a leak at 25cm H2O in a study 1974 taken to be associated with postintubation croup - biggest problem is in under 4 yo due to airway diameter, and frequent changes of head position Recent studies little difference for the correlation between presence or absence of leak and the severity of post intubation croup 2-3% cuffed or uncuffed post surgery 15% cuffed or uncuffed post PICU regardless of leak or duration of intubation (6-10% same in various age groups in a 2004 study of 600 children under 5) Less need to replace tube (around 20% in some studies) - ? Less but tube too small, or accept brief high pressure leak Better airway protection ? relevance No gas leak � good for staff and IPPV Smaller diameter tube � higher resistance ? Subglottic (tracheal) stenosis as an outcome measure � not all studies designed to pick it up. Still using uncuffed for young children

15. LMA As a face mask alternative Not with potential full stomach Possible for some dental/ENT work with minimal expected soiling Anaesthetist preference LMA As a face mask alternative Not with potential full stomach Possible for some dental/ENT work with minimal expected soiling � eg some minor extractions, simple restorative work Anaesthetist preference for others eg Tonsillectomy - quoted 4-9% replacement rate with ETT when gag opened , otherwise avoids muscle relaxants, potential smooth recovery � I always use ETT for tonsils LMA As a face mask alternative Not with potential full stomach Possible for some dental/ENT work with minimal expected soiling � eg some minor extractions, simple restorative work Anaesthetist preference for others eg Tonsillectomy - quoted 4-9% replacement rate with ETT when gag opened , otherwise avoids muscle relaxants, potential smooth recovery � I always use ETT for tonsils

16. Face Masks Rendell Baker � low deadspace Clear preferable � can see misting, vomitus, lip colour � pulse oximetry easily lost Rendell Baker � low deadspace Clear preferable � can see misting, vomitus, lip colour � pulse oximetry easily lost

17. Laryngeal Spasm Avoid CPAP & Oxygen Clear airway judiciously Deepen anaesthesia Topical lignocaine Very low dose Sux (� usual) Intubate/reintubate if needed Laryngeal spasm � cords clamped down Avoid � don�t extubate under light anaesthesia, ensure full reversal muscle relaxants, clear airway pre extubation, check for bleeding and clot, keep airway alignment on transfer, avoid upper airway obstruction CPAP and Oxygen � get equipment immediately and help Clear airway judiciously � need to balance chance of improvement vs risk of worsening Deepen anaesthesia (if intraop) Topical lignocaine Very low dose Sux (� usual) Intubate/reintubate if needed Laryngeal spasm � cords clamped down Avoid � don�t extubate under light anaesthesia, ensure full reversal muscle relaxants, clear airway pre extubation, check for bleeding and clot, keep airway alignment on transfer, avoid upper airway obstruction CPAP and Oxygen � get equipment immediately and help Clear airway judiciously � need to balance chance of improvement vs risk of worsening Deepen anaesthesia (if intraop) Topical lignocaine Very low dose Sux (� usual) Intubate/reintubate if needed

18. Difficult Intubation AVOID Refer to tertiary centre if possible Spontaneous ventilation gas induction Then??? DIFFICULT AIRWAY AVOID Refer to tertiary centre if possible � may not be with croup or epiglotitis, other impending airway closure or severe respiratory failure - honestly assess your ability as a team to do a safe surgical airway in a young child � needle cricothyroidotomy (fast, hard to locate, high risk damage) vs tracheostomy (slow, needs skill, infant rapidly hypoxic if obstructed) (gun anaesthetist or ENT surgeon if the rest are terrified of kids) Spontaneous ventilation gas induction Then??? � smaller tube with bendable stylet - be prepared for surgical airway - fibreoptic bronchoscope down LMA, guide wire down suction channel, then airway exchange catheter, then ETT - semirigid or rigid optical stylets � eg Bonfils, Shikani � both have very high success rates if combined with standard laryngoscope and laryngeal manipulation (next slide) but consider rapidly bleeding tonsillar bed - videolaryngoscopes � but may just help you see the ETT miss the larynx - fasttrach LMA only go down to 3DIFFICULT AIRWAY AVOID Refer to tertiary centre if possible � may not be with croup or epiglotitis, other impending airway closure or severe respiratory failure - honestly assess your ability as a team to do a safe surgical airway in a young child � needle cricothyroidotomy (fast, hard to locate, high risk damage) vs tracheostomy (slow, needs skill, infant rapidly hypoxic if obstructed) (gun anaesthetist or ENT surgeon if the rest are terrified of kids) Spontaneous ventilation gas induction Then??? � smaller tube with bendable stylet - be prepared for surgical airway - fibreoptic bronchoscope down LMA, guide wire down suction channel, then airway exchange catheter, then ETT - semirigid or rigid optical stylets � eg Bonfils, Shikani � both have very high success rates if combined with standard laryngoscope and laryngeal manipulation (next slide) but consider rapidly bleeding tonsillar bed - videolaryngoscopes � but may just help you see the ETT miss the larynx - fasttrach LMA only go down to 3

19. Shikani