Pediatric Airway Management: An Update HANY EL-ZAHABY, MD Anesthesia, Ain Shams University

Five Cardinal Anatomical Features of Infant’s Larynx 1- Higher Larynx Acute 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 airway Obligate nasal breathers Difficult 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 The only complete ring Narrowest part of infant’s larynx is the cricoid cartilage: Tight fitting ETT may cause edema. Uncuffed ETT preferred for patients < 8 years old

Respiratory Physiology Obligate 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 Physiology Respiratory 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 Physiology Tracheal 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 Physiology Dynamic Airway Obstruction Normal inspiratory stretch/collapse (crying) Dynamic collapse at inlet Bronchiolitis/asthma

Respiratory Physiology Work 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 Physiology Type 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 Anomalies Tumors Infection Musculoskeletal Problems

Encephalocele Hallermann-Streiff S. Pierre Robin S. Bilateral Cleft Palate Achondroplasia Down S.

Crouzon S. Seckel S. Treacher Collins S. Goldenhar S. Apert S. Nager S.

Mucopolysaccaridosis Type IH (Hurler) Type 1 H/S (Hurler-Scheie) Type II Hunter Type III (Sanfilippo)

Tumors Infection Cystic hygroma Hemangioma of tongue, pharynx Teratoma Retropharyngeal abscess Epiglottitis Laryngotracheobronchitis (subglottic croup) Ludwig’s angina Adenotonsillitis, abscess, hypertrophy ( obstructive sleep apnea) Scleroderma Laryngeal 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 Airway Head tilt- Chin lift - Jaw Thrust – Oropharyngeal Airway

Hazards: long, bleeding 30%, intracranial placement Techniques to open the Airway Nasopharyngeal Airway Size Hazards: 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 Macintoch Miller Age - Preterm Neonate 1 Neonate-2 Yrs 2 2-6 Yrs 6-12 Yrs 3 >12 Yrs

Tracheal Tube Sizes Insufflation Pressure ? Muscle Relaxants? Insertion length (Alveolar ridge) Size (mm ID) Age 6-9 cm 2.5 3.0 Preterm 1000g Preterm 1000-2500g 10 cm 3.0-3.5 Neonate-6 Month 11 cm 3.5-4.0 6 Month – 1 Yr 12 cm 4.0-5.0 1-2 Yrs age (yrs)/2 + 12 age (yrs)/4 + 4 Beyond 2 Yrs

Micro-cuff ETT More anatomical fit Sealing at low pressures More distal position Greater 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 Silicone Softer, deeper mask bowl, bite block, improves stability PVC Silicone

LMA sizes Largest TT (mm ID) Maximum cuff volume (ml) (Least effective volume) Patient’s weight Mask size 3.5 4 1-5 kg 1 4.0 7 5-10 kg 1.5 4.5 10 10-20 kg 2 5.0 14 20-30 kg 2.5 6.0, non-cuffed 20 > 30 kg 3

Special Techniques for Intubation Rigid 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 Stylet Light 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 airways Laryngosopic blades TT Stylets LMA Fiberoptic laryngoscope PC cricothyrotomy kit Jet ventilation eq. TT exchangers Exhaled CO2 detectors Experienced assistance IV access

Incomplete Airway Obstruction Apply gentle positive pressure Improved No improvement Eliminate noxious stimulus, + concentration of volatile anesthetic IV thiopentone/propofol, stabilize & resume anesthetic No improvement Improved No improvement Stabilize + resume anesthetic IV succinylcholine + atropine Ventilate with 100% oxygen + ETT Roy WL, Lerman J, Anaesthesia 1988:35, 93

Complete Airway Obstruction Jaw thrust, ventilate with 100% oxygen No improvement + no IV access Improvement Eliminate noxious stimulus, + concentration of volatile anesthetic Intubate immediately without relaxant No improvement + IV access Call for help spray cords with lidocaine, intubate Succinylcholine + atropine + intubate Ventilation 100% oxygen Ventilate + intubate Start CPR, cricothyrotomy

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.

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