Pediatric airway obstruction

Pediatric Airway Obstruction

Ibrahim Habib Barakat , MD

The Pediatric Airway

• Introduction

• Normal Anatomy

• Physiology

• Airway evaluation

• Management of normal vs. abnormal airway

• Difficult airway

Introduction

• Almost all of pediatric codes are due to respiratory origin

• 80% of pediatric cardiopulmonary arrest are primarily due to respiratory distress

• Majority of cardiopulmonary arrest occur at <1 year old

Normal Pediatric Airway Anatomy

• Larynx composed of

hyoid bone and a series

of cartilages

• Single: thyroid, cricoids,

epiglottis

• Paired: arytenoids,

corniculates, and

cuneiform

Pediatric Anatomy cont.

Laryngeal folds consist of:

• Paired aryepiglottic folds extend from epiglottis posteriorly to superior surface of arytenoids

• Paired vestibular folds (false vocal cords) extend from thyroid cartilage posteriorly to superior surface of arytenoids

• Paired vocal folds (true vocal cords) extend from posterior surface of thyroid plate to anterior part of arytenoids

• Interarytenoid fold bridging the arytenoid cartilages

• Thyrohyoid fold extend from hyoid bone to thyroid cartilage

Pediatric Anatomy cont.

Sensory Innervation:

Recurrent Laryngeal Nerve-supraglottic larynx

Internal Branch of Superior Laryngeal Nerve- infraglottic larynx

Motor Innervation:

External branch of Superior Laryngeal Nerve-cricothyroid muscle

Recurrent Laryngeal Nerve-all other laryngeal muscles

Blood Supply

Laryngeal branches of the superior and inferior thyroid arteries

5 Differences between Pediatric

and Adult Airway

• More rostral larynx

• Relatively larger tongue

• Angled vocal cords

• Differently shaped epiglottis

• Funneled shaped larynx-narrowest

part of pediatric airway is cricoid

cartilage

More rostral pediatric larynx

Laryngeal apparatus develops from brachial clefts and

descends caudally

Infant’s larynx is higher in neck (C2-3) compared to adult’s

(C4-5)

Relatively larger tongue

• Obstructs airway

• Obligate nasal breathers

• Difficult to visualize larynx

• Straight laryngoscope blade completely elevates the epiglottis, preferred for pediatric laryngoscopy

Angled vocal cords

• Infant’s vocal cords have more angled attachment to trachea, whereas adult vocal cords are more perpendicular

• Difficulty in nasal intubations where “blindly” placed ETT may easily lodge in anterior commissure rather than in trachea

Image from: http://www.utmb.edu/otoref/Grnds/Pedi-airway-2001-

01/Pedi-airway-2001-01-slides.pdf

Adult epiglottis broader,

axis parallel to trachea

Differently shaped epiglottis

Infant epiglottis ohmega (Ώ) shaped

and angled away from axis of trachea


More difficult to lift an infant’s

epiglottis with laryngoscope blade


Funneled shape larynx

• narrowest part of infant’s larynx is the undeveloped cricoid cartilage, whereas in the adult it is the glottis opening (vocal cord)

• Tight fitting ETT may cause edema and trouble upon extubation

INFANT ADULT

Funneled shape larynx

• Uncuffed ETT preferred for patients < 8 years old

• Fully developed cricoid cartilage occurs at 10-12 years of age

INFANT ADULT

Pediatric Respiratory Physiology

• Pulmonary surfactant produced by Type II pneumocytes

at 24 wks GA

• Sufficient pulmonary surfactant present after 35 wks GA

• Premature infants prone to respiratory distress syndrome

(RDS) because of insufficient surfactant

• Betamethasone can be given to pregnant mothers at 24-35wks GA to accelerate fetal surfactant production

Pediatric Respiratory Physiology

• Extrauterine life not possible until 24-25 weeks of gestation

• Two types of pulmonary epithelial cells: Type I and Type II pneumocytes

• Type I pneumocytes are flat and form tight junctions that interconnect the interstitium

• Type II pneumocytes are more numerous, resistant to oxygen toxicity, and are capable of cell division to produce Type I pneumocytes

Pediatric Respiratory Physiology cont.

• Work of breathing for each kilogram of body weight is similar in infants and adult

• Oxygen consumption of infant (6 ml/kg/min) is twice that of an adult (3 ml/kg/min)

• Greater oxygen consumption = increased respiratory rate

•

• Tidal volume is relatively fixed due to anatomic structure

Pediatric Respiratory Physiology cont.

• Minute alveolar ventilation is more dependent on increased respiratory rate than on tidal volume

• Lack Type I muscle fibers, fatigue more easily

• FRC of an awake infant is similar to an adult when normalized to body weight

• Ratio of alveolar minute ventilation to FRC is doubled, under circumstances of hypoxia, apnea or under anesthesia, the infant’s FRC is diminished and desaturation occurs more precipitously

Physiology: Effect Of Edema

Poiseuille’s law

R = 8nl/ πr4

If radius is halved, resistance increases 16 x Image from: http://www.hadassah.org.il/NR/rdonlyres/59B531BD-EECC-4FOE-9E81-14B9B29D139B1945/AirwayManagement.ppt

Normal Inspiration and Expiration

turbulence

Image from: http://www.hadassah.org.il/NR/rdonlyres/59B531BD-EECC-4FOE-9E81-14B9B29D139B1945/AirwayManagement.ppt

Obstructed Airways

turbulence &

wheezing

Evaluation of acute upper airway

obstruction in children

• URI predisposes to coughing, laryngospasm, bronchospasm, desat during anesthesia

• Snoring or noisy breathing (adenoidal hypertrophy, upper airway obstruction, OSA)

• Chronic cough (subglottic stenosis, previous tracheoesohageal fistula repair)

• Productive cough (bronchitis, pneumonia)

• Sudden onset of new cough (foreign body aspiration)

Airway Evaluation Medical History

• Inspiratory stridor (macroglossia, laryngeal web, laryngomalacia, extrathoracic foreign body)

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

• Asthma and bronchodilator therapy

(bronchospasm)

• Repeated pneumonias (GERD, CF, bronchiectasis, tracheoesophageal fistula, immune suppression, congenital heart disease)

• History of foreign body aspiration


• Previous anesthetic problems (difficulty intubation/extubation or difficulty with mask ventilation)

• Atopy, allergy (increased airway reactivity)

• History of congenital syndrome

(Pierre Robin Sequence, Treacher Collins, Klippel-Feil, Down’s Syndrome, Choanal atresia)

• Environmental: smokers


Signs of Impending Respiratory Failure

• Increase work of breathing

• Tachypnea/tachycardia

• Nasal flaring

• Drooling

• Grunting

• Wheezing

• Stridor

Subglottic

Trachea

Glottic Supraglottic

High-pitched stridor

Inspiratory stridor

Biphasic stridor Sonorous, gurgling

Coarse,

expiratory stridor,

Sound

Subglottic trachea Larynx

Vocal cords

Nose / Pharynx / Epiglottis Structures

Subglottic stenosis

Tracheomalacia

Tracheal stenosis

Vascular ring

Hemangioma cyst

Laryngomalacia

Vocal cord paralysis

Laryngeal web

Laryngocele

Micrognathia ,Pierre Robin

Macroglossia,

Down syndrome

Storage disease

Choanal atresia

Lingual thyroid

Thyroglossal cyst

Congenital

Croup

Bacterial tracheitis

Subglottic stenosis

Foreign body

Papillomas

Foreign body

Adenopathy

Tonsillar hypertrophy

Foreign body

Pharyngeal abscess

Epiglottitis

Acquired

Causes of Stridor: Anatomic Location, Sound, and Etiology

Signs of Impending Respiratory Failure

• Head bobbing

• Use of accessory muscles/retraction of muscles

• Cyanosis despite O2

• Irregular breathing/apnea

• Altered consciousness/agitation

• Inability to lie down

• Diaphoresis

Causes of acute upper airway obstruction that

are commonly life-threatening

Epiglottitis

Retropharyngeal abscess

Bacterial tracheitis

Croup

Foreign body

Anaphylaxsis

Neck trauma

Burns thermal or caustic

Airway Evaluation Physical Exam

• Facial expression

• Nasal flaring

• Mouth breathing

• Drooling

• Color of mucous membranes

• Retraction of suprasternal, intercostal or subcostal

• Respiratory rate

• Voice change

• Mouth opening

• Size of mouth

Airway Evaluation Physical Exam

• Mallampati

• Loose/missing teeth

• Size and configuration of palate

• Size and configuration of mandible

• Location of larynx

• Presence of stridor (inspiratory/expiratory)

• Baseline O2 saturation

• Global appearance (congenital anomalies)

• Body habitus

Diagnostic Testing

• Laboratory and radiographic evaluation extremely helpful with pathologic airway

• AP and lateral films and fluoroscopy may show site and cause of upper airway obstruction

• MRI/CT more reliable for evaluating neck masses, congenital anomalies of the lower airway and vascular system

Imaging may be

useful in identifying

the location and nature

of the airway

obstruction but should never interfere

with the stabilization of a child with

a critical obstruction.

Diagnosis …. ?

Retropharyngeal

abscess

Retropharyngeal space :

>7 mm @ C2

Retrotracheal space :

14 mm@ C6 .. Ped

22 mm @ C6 .. Adult

retropharyng

Abnormal retropharyngeal space:

F. B. ingestion

MRI/CT

Usually not useful in an acute setting

More reliable for evaluating neck masses and

congenital anomalies of the lower airway

and vascular system

http://www.uhrad.com/pedsarc/peds017a.jpg

Diagnostic Testing

• Perform radiograph exam only when there is no immediate threat to the child’s safety and in the presence of skilled personnel with appropriate equipment to manage the airway

• Intubation must not be postponed to obtain radiographic diagnosis when the patient is severely compromised.

• Blood gases are helpful in assessing the degree of physiologic compromise; however, performing an arterial puncture on a stressed child may aggravate the underlying airway obstruction

Flexible Laryngoscopy:

Proper Equipment

Assess nares/choanae

Assess adenoid and

lingual tonsil

Assess TVC mobility

Assess laryngeal

structures

Airway Management: Normal Airway

• Challenging because of unique anatomy

and physiology

• Goals: protect the airway, adequately

ventilate, and adequately oxygenate

• Failure to perform any ONE of these tasks

will result in respiratory failure

• Positioning is key!

Bag-Mask Ventilation

•Clear, plastic mask with inflatable rim

provides atraumatic seal

•Proper area for mask application-bridge

of nose extend to chin

•Maintain airway pressures <20 cm H2O

•Place fingers on mandible to avoid

compressing pharyngeal space

•Hand on ventilating bag at all times to

monitor effectiveness of spontaneous breaths

•Continous postitive pressure when needed

to maintain airway patency


Oropharyngeal Airway

SIZE

PROPER

POSITION


Oropharyngeal Airway Placement

Image from: http://depts.Washington.edu/pccm/Pediatric%20Airway%20management.ppt

Nasopharyngeal Airway

•Distance from nares to angle of mandible approximates the

proper length

•Nasopharyngeal airway available in 12F to 36F sizes

•Shortened endotracheal tube may be used in infants or small

children

•Avoid placement in cases of hypertrophied adenoids -

bleeding and trauma


Sniffing Position

Image from: http://depts.Washington.edu/pccm/Pediatric%20Airway%20management.ppt

Patient flat on operating table, the oral (o),

pharyngeal (P), and tracheal (T) axis pass

through

three divergent planes

A blanket placed under the occiput aligns the

pharyngeal (P) and tracheal (T) axes

Extension of the atlanto-occipital joint aligns the

oral (O), pharyngeal (P), and tracheal (T) axes

Selection of laryngoscope blade:

Miller vs. Macintosh

• Miller blade is preferred for infants and younger children

• Facilitates lifting of the epiglottis and exposing the glottic opening

• Care must be taken to avoid using the blade as a fulcrum with pressure on the teeth and gums

• Macintosh blades are generally used in older children

• Blade size dependent on body mass of the patient and the preference of the anesthesiologist

Endotracheal Tube

Age Wt ETT(mm ID) Length(cm)

Preterm 1 kg 2.5 6

1-2.5 kg 3.0 7-9

Neonate-6mo 3.0-3.5 10

6 mo-1 3.5-4.0 11

1-2 yrs 4.0-5.0 12

Endotracheal Tube

New AHA Formulas:

Uncuffed ETT:

(age in years/4) + 4

Cuffed ETT: (age in years/4) +3

ETT depth (lip): ETT size x 3

Complications of Endotracheal Intubation

• Postintubation Croup

• Incidence 0.1-1%

• Risk factors: large ETT, change in patient

position introp, patient position other than

supine, multiple attempts at intubation,

traumatic intubation, pts ages 1-4, surgery

>1hr, coughing on ETT, URI, h/o croup

• Tx: humidified mist, nebulized racemic

epinephrine, steroid

Complications of Endotracheal Intubation

• Laryngotracheal (Subglottic) Stenosis

• Occurs in 90% of prolonged endotracheal

intubation

• Lower incidence in preterm infants and

neonates due to relative immaturity of cricoid

cartilage

• Pathogenesis: ischemic injury secondary to

lateral wall pressure from ETT edema,

necrosis, and ulceration of mucosa, infx

• Granulation tissues form within 48hrs leads

to scarring and stenosis

Cuff vs Uncuffed Endotracheal Tube

• Controversial issue

• Traditionally, uncuffed ETT recommended in children < 8 yrs old to avoid post-extubation stridor and subglottic stenosis

• Arguments against cuffed ETT: smaller size increases airway resistance, increase work of breathing, poorly designed for pediatric pts, need to keep cuff pressure < 25 cm H2O

• Arguments against uncuffed ETT: more tube changes for long-term intubation, leak of anesthetic agent into environment, require more fresh gas flow > 2L/min, higher risk for aspiration

Cuff vs Uncuffed Endotracheal Tube

-Concluding Recommendations-

• For “short” cases when ETT size >4.0, choice of cuff vs uncuffed probably does not matter

• Cuffed ETT preferable in cases of: high risk of aspiration (ie. Bowel obstruction), low lung compliance (ie. ARDS, pneumoperitoneum, CO2 insufflation of the thorax, CABG), precise control of ventilation and pCO2 (ie. increased intracranial pressure, single ventricle physiology)

Laryngeal Mask Airway

• Supraglottic airway device developed by Dr.

Archie Brain

• Flexible bronchoscopy, radiotherapy, radiologic

procedures, urologic, orthopedic, ENT and

ophthalmologic cases are most common pediatric

indications for LMA

• Useful in difficult airway situations, and as a

conduit of drug administration (ie. Surfactant)

• Different types of LMAs: Classic LMA, Flexible

LMA, ProSeal LMA, Intubating LMA

• Disadvantages: Laryngospasm, aspiration

Laryngeal Mask Airway

LMA size Weight Max cuff volume (mL) ETT (mID)

1 .0 Neonate/Infants ≤ 5kg 4 3.5

1.5 Infants 5-10kg 7 4.0

2.0 Infants/children 10-20kg 10 4.5

2.5 Children 20-30kg 14 5.0

3.0 Children/small adult > 30kg 20 6.0 cuff

4.0 Normal/large adolescent/adult 30 7.0 cuff

5.0 Large adolescent/adult 40 8.0 cuff

Other Supraglottic Devices

• Laryngeal tube

• Latex-free, single-lumen silicone tube, which is closed at distal end

• Two high volume-low pressure cuffs, a large proximal oropharyngeal

cuff and a smaller distal esophageal cuff

• Both cuffs inflated simultaneously via a single port

• Situated along length of oropharynx with distal tip in esophagus

• Sizes 0-5, neonates to large adults (only sizes 3-5 available in US)

• Limited data available for its use in children

Other Supraglottic Devices

• Cobra Perilaryngeal Airway

• Perilaryngeal airway device with distal end shaped like a cobra-head

• Positioned into aryepiglottic folds and directly seats on entrance to

glottis

• Inflation of the cuff occludes the nasopharynx pushing the tongue and

soft tissues forward and preventing air leak

• Available in sizes pediatric to adult ½ to 6

• No studies currently available evaluating this device in children

Difficult Airway Management Techniques

• Rigid bronchoscopy

• Flexible bronchoscopy

• Direct laryngoscopy

• Intubating LMA

• Lighted stylet

• Bullardscope

• Fiberoptic intubation

• Surgical airway

Tracheotomy

Cricothyroidotomy is difficult

b/c of small membrane and

flexibility

Early complications

Pneumothorax, bleeding,

decannulation, obstruction,

infections

Late complications

Granuloma, decannulation,

SGS, tracheocutaneous

fistula

Airway Management

Classification of Abnormal Pediatric Airway

• Congenital Neck Masses (Dermoid cysts, cystic teratomas, cystic hygroma, lymphangiomas, neurofibroma, lymphoma, hemangioma)

• Congenital Anomalies (Choanal atresia,tracheoesophageal fistula, tracheomalacia, laryngomalacia, laryngeal stenosis, laryngeal web, vascular ring, tracheal stenosis)

• Congenital Syndromes (Pierre Robin Syndrome, Treacher Collin, Turner, Down’s, Goldenhar , Apert, Achondroplasia, Hallermann-Streiff, Crouzan)

Airway Management

Classification of Abnormal Pediatric Airway

• Inflammatory (Epiglottitis, acute tonsillitis, peritonsillar abscess,retropharyngeal abscess, laryngotracheobronchitis,bacterial tracheitis,adenoidal hypertrophy,nasal congestion, juvenile rheumatoid arthritis)

• Traumatic/Foreign Body (burn,laceration,lymphatic/venous obstruction,fractures/dislocation, inhalational injury, postintubation croup (edema),swelling of uvula

• Metabolic (Congenital hypothyroidism, mucopolysaccharidosis, Beckwith-Wiedemann Syndrome,glycogen storage disease, hypocalcemia laryngospasm)

Congenital Neck Masses

Congenital Anomalies

Tracheoesphageal Fistula



• Feeding difficulties (coughing, choking and cyanosis) and breathing problems

• Associated with congenital heart (VSA, PDA, TOF), VATER, GI, musculoskeletal and urinary tract defects

• Occurs in 1/ 3000-5000 births

• Most common type is the blind esophageal pouch with a fistula between the trachea and the distal esophagus (87%)



Radiograph of a neonate with suspected esophageal atresia. Note the nasogastric tube coiled in the proximal esophageal pouch (solid arrow). The prominent gastric bubble indicates a concurrent tracheoesphageal fistula (open arrow)


Choanal Atresia

• Complete nasal obstruction of the newborn

• Occurs in 0.82/10 000 births

• During inspiration, tongue pulled to palate, obstructs oral airway

• Unilateral nare (right>left)

• Bilateral choanal atresia is airway emergency

• Death by asphyxia

• Associated with other congenital defects


Choanal Atresia

Clinical manifestations

• - unilateral :

Asymptomatic for along period till the first attack of upper

respiratory tract infection,diagnosis may be suggested by

nasal discharge or persistent nasal obstruction .

• - bilateral :

Difficulty with mouth breathing make vigerous attempts to

inspire , often suck in their lips ,and develop cyanosis .

Distressed children then cry ( which relieve the cyanosis ) and

become more calm with normal skin colour , only to repeat

the cycle after closing their mouths . Those who are able to

breath through their mouths at once experience difficulty

when suckling and swallowing , becoming cyanotic when

they attempt to feed .

diagnosis

• - inablity to pass afirm cather 3 to 4 cm

into the nasopharynx through each nostril .

• - the atritic plate can be seen directly with

fibro optic rhinoscopy .

• -the anatomy is best evaluated by using

high resolution CT scan .

treatment

• - bilateral : -

• - An oral airway or intubation .

• - trasnasal endoscopic surgical repair .

• - stents are usually left in place after the repair for

weeks to prevent restenosis or closure .

• - tracheostomy should be considered in child has

other potentially life threatening problems and in

whom early surgical repair of the choanal atresia

may not be appropriate or feasible .

treatment

• - unilateral :-

• - operative correction may be deffered for

several years

• - in both nuilateral or bilateral cases ,

restenosis necessitating dilatation or

reoperation , or both , is common .

• - mitomycin-c has been used to help

prevent the development of granulation

tissue and stenosis .

Congenital Syndromes

Pierre Robin Sequence

• Occurs in 1/8500 births

• Autosomal recessive

• Mandibular hypoplasia, micrognathia,

cleft palate, retraction of inferior dental

arch, glossptosis

• Severe respiratory and feeding

difficulties

• Associated with OSA, otitis media,

hearing loss, speech defect, ocular

anomalies, cardiac defects,

musculoskeletal (syndactyly, club feet),

CNS delay, GU defects)

Congenital Syndromes

Pierre Robin Sequence

Congenital Syndrome

Treacher Collins Syndrome

• Mandibulofacial dysotosis

• Occurs in 1/10 000 births

• Cheek bone and jaw bone underdeveloped

• External ear anamolies, drooping lower eyelid, unilateral absent thumb

• Respiratory difficulties

• Underdeveloped jaw causes tongue to be positioned further back in throat (smaller airway)

• Associated with OSA, hearing loss, dry eyes

Congenital Syndrome

Treacher Collins Syndrome

Congenital Syndrome

Down’s Syndrome

• Trisomy 21

• Occurs in 1/660 births

• Short neck, microcephaly, small mouth with large protruding tongue, irregular dentition, flattened nose, and mental retardation

• Associated with growth retardation, congenital heart disease, subglottic stenosis, tracheoesophageal fistula, duodenal atresia, chronic pulmonary infection, seizures, and acute lymphocytic leukemia

• Atlantooccipital dislocation can occur during intubation due to congenital laxity of ligaments

Congenital Syndrome

Down’s Syndrome

Inflammatory (Epiglottitis)

• Etiology: Haemophilus influenzae type B

• Occurs in children ages 2-6 years

• Disease of adults due to widespread H. influenza vaccine

• Progresses rapidly from a sore throat to dysphagia and complete airway obstruction (within hours)

• Signs of obstruction: stridor, drooling, hoarseness, tachypnea, chest retraction, preference for upright position

• OR intubation/ENT present for emergency surgical airway

• Do NOT perform laryngoscopy before induction of anesthesia to avoid laryngospasm

• Inhalational induction in sitting position to maintain spontaneous respiratory drive (Sevo/Halothane)

• Range of ETT one-half to one size smaller

Inflammatory

The treatment of epiglottitis. Instrumentation: Avoid instrumentation. In suspected

epiglottitis.

Specialist consult: An anesthesiologist or otorhinolaryngologist

should be involved early in the management of epiglottitis.

Monitoring: Patients must be monitored for respiratory fatigue

visually and with continuous pulse oximetry. Accessibility to

equipment and expertise for immediate intubation is required

in the event of respiratory failure. If endotracheal intubation is

not possible, cricothyroidotomy may be required.

Oxygen: Oxygen is administered according to pulse oximetry

results. Dry air may worsen inflammation. Use of humidified

oxygen or a room humidifier is recommended.

Antibiotics: Presumptive intravenous antibiotics are indicated,

tailored to results from blood cultures.

The treatment of epiglottitis.

Glucocorticoids: Either intravenous or inhaled glucocorticoids

are sometimes given to reduce inflammation. However,

controlled trials of the effectiveness of this approach in

epiglottitis are limited.

Volume deficits: Correct volume deficits with intravenous fluids.

Sedatives: Avoid sedatives that may suppress the respiratory

drive.

Other medications: In patients with croup, aerosolized racemic

epinephrine is sometimes used to reduce mucosal edema;

however, the role of this drug in persons with epiglottitis is

not defined. Adverse events have been reported in patients

with epiglottitis.24 Beta-2 agonists are not typically used in

patients who do not have asthma

Inflammatory

• Etiology: Parainfluenza virus

• Occurs in children ages 3 months to 3 years

• Barking cough

• Progresses slowly, rarely requires

intubation

• Medically managed with oxygen and mist

therapy, racemic epinephrine neb and IV

dexamethasone (0.25-0.5mg/kg)

• Indications for intubation: progressive

intercostal retraction, obvious respiratory

fatigue, and central cyanosis

Inflammatory

Croup / steepling of the subglottic trachea

Metabolic

Beckwith-Wiedemann Syndrome

• Occurs in 1/13000-15000 births

• Chr 11p.15.5

• Autosomal dominant

• Macroglossia, Exomphalos, Gigantism

• Associated with mental retardation, organomegaly, abdominal wall defect, pre- and postnatal overgrowth, neonatal hypoglycemia, earlobe pits, Wilms tumor

Metabolic

Beckwith-Wiedemann Syndrome

Management

Management of complete airway obstruction in children

Management of severe upper airway obstruction in children

Pediatric airway obstruction

Education

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