Pediatric Airway Management:An Update

HANY EL-ZAHABY, MD

Anesthesia, Ain Shams University

Five Cardinal Anatomical Featuresof Infant’s Larynx

1- Higher LarynxAcute angulation between plane of tongue & plane of glottis makes exposure difficult ►straight blade ►exaggerated by mandibular hypoplasia (Pierre Robin syndrome).

2- Relatively Larger Tongue:Obstructs airwayObligate nasal breathersDifficult to manipulate & stabilize with laryngoscopic blades

3- Anteriorly Angulated Vocal Cords:

The anterior attachment of vocal cords are lower than posterior attachment ► difficulty in nasal intubations where “blindly” placed ETT lodges in the anterior commissure rather than in the trachea.

4- Differently Shaped Epiglottis

Infant epiglottis ohmega (Ώ) shaped and angled away from axis of trachea

More difficult to lift an infant’s epiglottis with laryngoscopic blade

5 -Funnel shaped larynx

Narrowest part of infant’s larynx is the cricoid cartilage :Tight fitting ETT may cause edema.Uncuffed ETT preferred for patients < 8 years old

The only complete ring

Respiratory PhysiologyObligate nasal breathers

Immaturity of coordination between respiratory efforts and oropharyngeal motor/sensory input.

During quiet respiration, the tongue rests against the roof of the mouth.

Respiratory PhysiologyRespiratory Parameters

High metabolic rate (5-8 ml/kg/min)

Tidal volume (6-7 ml/kg/min)

High respiratory rate (40-60 breaths/min)

High alveolar ventilation (130 ml/kg/min)

Lung compliance is less while chest wall compliance is more than those in adults {reduced FRC and atelectasis} ►PEEP.

Respiratory PhysiologyTracheal and Bronchial Function

Infant's larynx, trachea, and bronchi are highly compliant and hence more subject to distention and compression forces

The intrathoracic trachea is subject to stresses that are different from those in the extrathoracic portion

Respiratory PhysiologyDynamic Airway Obstruction

Normal inspiratorystretch/collapse

(crying)

Dynamic collapseat inlet

Bronchiolitis/asthma

Respiratory PhysiologyWork of Breathing

• The work of breathing is needed to overcome the chest wall compliance and the resistance of the airways.

• The WOB per kilogram is similar to adults. • The nasal passages account for 25% of the total

resistance to airflow in a neonate, compared with 60% in an adult. In infants, most resistance to airflow occurs in the bronchial and small airways ► respiratory failure with bronchiolitis.

• Long, small ETT, obstructed ETT, narrowed airway ► increased WOB ► increased oxygen consumption ► increases oxygen demand.

Change in work of breathing after placement of an appropriate endotracheal tube in extremely low birth weight infants (<1000 g), premature infants (1500 g), full-term infants, children, and adults

Respiratory Physiology Effect of Edema on WOB

Respiratory PhysiologyType I Muscle Fibers

Unable to sustain increased WOB for long periods

Evaluation of the Upper Airway (History)

URTI Snoring (adenoidal hypertrophy, obstructive sleep

apnea) Croupy cough (subglottic stenosis, TEF repair,

F.B.aspiration) Inspiratory stridor (subglottic stenosis or web,

laryngomalacia, macroglossia, extrathoracic F.B. or extrathoracic tracheal compression)

Hoarse voice (laryngitis, vocal cord palsy, papillomatosis, granuloma)

Asthma Repeated pneumonias Previous anesthetic problem

Evaluation of the Upper Airway (Physical Examination)

Facial expression Nasal flaring Mouth breathing Color of mucous membranes Retractions (suprasternal, intercostal, subcostal) Respiratory rate Voice change Mouth opening Size of mouth Size of tongue and its relationship to other pharyngeal

structures (Mallampati)?

Loose or missing teeth. Size and configuration of palate. Size and configuration of mandible (side view). Location of larynx in relation to the mandible. Presence of inspiratory stridor :epiglottitis, croup,

extrathoracic foreign body. Both inspiratory and expiratory stridor: aspirated foreign

body, vascular ring, or large esophageal foreign body. Prolonged expiration: lower airway disease? Baseline oxygen saturation in room air.

Bilateral microtia (ear deformity easily notable) is associated with mandibular hypoplasia & difficulty in visualizing the laryngeal inlet (42%) & with unilateral microtia (2.5%).

Are there congenital anomalies that may fit a recognizable syndrome? The finding of one anomaly mandates a search for others.

Evaluation of the Upper Airway (Diagnostic Testing)

X-ray, MRI and CT.

Radiologic airway examination in a child with a compromised airway must be undertaken only when

there is no immediate threat to the child's safety and only in the presence of skilled and appropriately equipped

personnel able to manage the airway . Endoscopic evaluation (flexible fiberoptic endoscopy) Arterial blood gas analysis (chronic airway obstruction

with respiratory acidosis)

Causes of Difficult Airway

Congenital AnomaliesTumorsInfectionMusculoskeletal Problems

Encephalocele Pierre Robin S.

Down S.Bilateral Cleft Palate Achondroplasia

Hallermann-Streiff S.

Crouzon S. Seckel S. Treacher Collins S.

Apert S. Nager S.

Goldenhar S.

Mucopolysaccaridosis

Type IH (Hurler)

Type III (Sanfilippo)

Type 1 H/S (Hurler-Scheie)

Type II Hunter

Tumors

Cystic hygroma Hemangioma of tongue, pharynx

Teratoma

Infection

Retropharyngeal abscess Epiglottitis

Laryngotracheobronchitis )subglottic croup( Ludwig’s angina

Adenotonsillitis, abscess, hypertrophy ( obstructive sleep apnea)SclerodermaLaryngeal web

Musculoskeletal Problems

Ankylosis of jaw, cervical spine

Unstable or dislocated cervical vertebrae

Wired jaw

Cervical cord tumor

Halo traction apparatus

Facial trauma, fractures, laceration, burns

Techniques to Open the AirwayHead tilt- Chin lift - Jaw Thrust – Oropharyngeal Airway

Techniques to open the AirwayNasopharyngeal AirwayTechniques to open the AirwayNasopharyngeal Airway

SizeSize

Hazards: long, bleeding 30%, intracranial placementHazards: long, bleeding 30%, intracranial placement

Aligning of the Upper Airway Axes ( More than 6 Years Old)

Three-axes theory?

Ventilation Techniques Multi-handed Mask Ventilation

Tracheal Intubation Laryngoscopic Blade Sizes

AgeMillerMacintoch

Preterm0-

Neonate0-

Neonate-2 Yrs1-

2-6 Yrs-2

6-12 Yrs22

<12 Yrs33

Tracheal Tube Sizes Insufflation Pressure ?Muscle Relaxants?

AgeSize (mm ID)Insertion length

)Alveolar ridge(

Preterm 1000g

Preterm 1000-2500g

2.5

3.0

6-9 cm

Neonate-6 Month3.0-3.510 cm

6 Month – 1 Yr3.5-4.011 cm

1-2 Yrs4.0-5.012 cm

Beyond 2 Yrsage (yrs)/4 + 4 age (yrs)/2 + 12

Micro-cuff ETT

More anatomical fit Sealing at low pressuresMore distal positionGreater permeability for nitrous oxide

For neonates ≤3 kg and infants ≤1 year, ID 3.0-mm

For children 1 to 2 years of age, ID 3.5-mm

For children ≥2 years, ID (mm) = age/4 + 3.5

Post-intubation croup was 0.4% (2/500 children)

LMA: Reusable Classic, Disposable Unique, ProSeal

SiliconePVCSiliconeSofter, deeper mask bowl, bite block, improves stability

LMA sizes

Mask sizePatient’s weightMaximum cuff volume (ml)

)Least effective volume(

Largest TT (mm ID)

11-5 kg43.5

1.55-10 kg74.0

210-20 kg104.5

2.520-30 kg145.0

3 <30 kg206.0 ,non-cuffed

Special Techniques for IntubationRigid Laryngoscopy The retromolar, paraglossal, or lateral approach to rigid laryngoscopy utilizing a straight blade.

Optimal External Laryngeal Manipulation (OELM)OELM is particularly helpful for infants & children with immobile or

shortened necks.

Either by an assistant or the laryngoscopist.

Intubation Guides

Lighted StyletLight Wand

Glidescope Video Laryngoscope

Intubation through LMA (Blind)

Fibreoptic Intubation through LMA

Fibreoptic Assisted Intubation

Percutaneous Cricothyrotomy

Percutaneous needle cricothyrotomy provides only a mean for oxygen insufflation and does not reliably provide adequate ventilation.

If glottic or subglottic pathology is not suspected, LMA placement to establish ventilation may be appropriately attempted first.

Retrograde Intubation

• Awake approach? • Sedation?• General anesthesia (inhalation/IV)?

“Assisted spontaneous ventilation during inhaled anesthesia is the preferred technique when

abnormal airway anatomy is present”.

Rules

“To avoid trouble one must be prepared for trouble”

“Have an IV access & experienced assistant”

“Do what you masters”

“Have definitive plan A, but have plan B & C”

Rules

“Use your common sense”

“ Do not continue to do the same thing and expect different results’’

“Easier comes first”

“Each difficult intubation is a different”

Difficult Airway Cart

Oropharyngeal/nasopharyngeal airwaysLaryngosopic bladesTTStyletsLMAFiberoptic laryngoscopePC cricothyrotomy kitJet ventilation eq.TT exchangersExhaled CO2 detectorsExperienced assistanceIV access

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Incomplete Airway Obstruction

Apply gentle positive pressure

Eliminate noxious stimulus ,+ concentration of volatile anesthetic

IV thiopentone/propofol, stabilize& resume anesthetic

Stabilize + resume anesthetic IV succinylcholine + atropineVentilate with 100% oxygen + ETT

No improvementImproved

Improved No improvementNo improvement

Roy WL, Lerman J, Anaesthesia 1988:35, 93

Complete Airway Obstruction

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Jaw thrust, ventilate with 100% oxygen

Intubate immediately without relaxant

Eliminate noxious stimulus , + concentration of

volatile anesthetic

Call for help spray cords with lidocaine,

intubate

Start CPR, cricothyrotomy

Succinylcholine + atropine +

intubate

Ventilation 100% oxygen

Ventilate + intubate

No improvement+ no IV access

Improvement

No improvement+ IV access

Extubation of Difficult Intubation Patient

Facial Grimacing

Documentation

1.Whether or not mask ventilation was attempted and, if there was a special maneuver needed?

2.Any difficulty with intubation?

3.What Special technique that was required for successful intubation?  

4.What special technique that was not helpful for intubation?

5. What grade of laryngoscopic view of laryngeal structures during rigid laryngoscopy?

Conclusion

Successful management of the difficult airway depends on prediction, preparation, maintenance of good oxygenation and ventilation, and the use of familiar tools by experienced physician.

THANK YOU