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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 (¼ 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 (¼ 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 (¼ 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