Transcript The Respiratory System

Lec 1
By
Dr. Athal Humo
2016-2017
Upper Airway Obstruction (UAO)
• UAO, is defined as blockage of any part of the airway
located above the thoracic inlet, can range from
nasal obstruction due to the common cold to lifethreatening obstruction of the larynx or upper trachea
(subglottic space).
ETIOLOGY
• The differential diagnosis of airway obstruction varies
with patient age and can also be subdivided into
supraglottic and subglottic causes
Age-Related Differential Diagnosis of Upper Airway
Obstruction
NEWBORN
Congenital subglottic stenosis (uncommon)
Choanal atresia
Micrognathia (Pierre Robin syndrome, DiGeorge syndrome)
Macroglossia (Beckwith-Wiedemann syndrome, Down, hypothyroidism)
Laryngeal web, clefts, atresia
Laryngospasm (intubation, aspiration, transient)
Vocal cord paralysis/paresis
Pharyngeal collapse
Dislocated nasal cartilage
INFANCY
Laryngomalacia (most common etiologic disorder)
Subglottic stenosis (congenital, acquired, e.g., after intubation)
Airway hemangioma
Tongue (macroglossia, tumor (dermoid, teratoma, ectopic thyroid)
Laryngeal papillomatosis
Vascular rings/slings
Rhinitis
TODDLERS
Viral croup
Spasmodic/recurrent croup
Bacterial tracheitis (toxic, high fever)
Foreign body (airway or esophageal)
Laryngeal papillomatosis
Retropharyngeal abscess
Hypertrophied tonsils and adenoids
OLDER CHILDREN
Epiglottitis
Inhalation injury (burns, toxic gas, hydrocarbons)
Foreign bodies
Angioedema (familial history, cutaneous angioedema)
Anaphylaxis (allergic history, wheezing, hypotension)
Trauma (tracheal or laryngeal fracture)
Peritonsillar abscess (adolescents)
Mononucleosis
CLINICAL MANIFESTATIONS
• Upper
airway
inspiration.
obstruction
is
more
pronounced
during
• The respiratory noise most commonly associated with upper
airway obstruction is stridor, a harsh sound caused by the
vibration of the airway structures mainly in inspiration.
Occasionally stridor may also be present on exhalation.
• Stridor often decreases during sleep due to lower inspiratory
flow rates and increase during feeding , excitement, & agitation.
• Hoarseness suggests vocal cord involvement.
DIAGNOSTIC STUDIES
• Radiographic evaluation of a child with stridor may not be helpful. However,
• Lateral views of the neck and nasopharynx can assess for adenoid hypertrophy &
airway swelling.
• AP views of the neck taken with the head in extension, the subglottic space should be
symmetrical and the lateral walls of the airway should fall away steeply. Asymmetry
suggests subglottic stenosis or a mass lesion, while tapering suggests subglottic
edema. However, these findings may be subtle.
• Computed tomography (CT) scans of the upper airway can help delineate the site of the
obstruction but may require sedation in younger children.
• Flexible nasopharyngoscopy, which can be done without sedation, is extremely useful
in assessing airway patency, the presence of adenoid tissue, vocal cord, laryngomalacia
and other airway lesions,.
• Bronchoscopy can be useful in assessing the subglottic space and intrathoracic large
airways, but this procedure requires deep sedation.
The Common Cold
• The common cold is a viral illness in which the
symptoms of rhinorrhea and nasal obstruction are
prominent; systemic symptoms and signs such as
myalgia and fever are absent or mild. It is often
termed rhinitis but includes self-limited involvement
of the sinus mucosa and is more correctly termed
rhinosinusitis.
• Most common pathogens associated with the
common cold are the rhinoviruses. Rarely it is
caused by influenza, PIV, RSV ,or adenovirus.
• Clinical Manifestations:
The onset of common cold symptoms typically occurs 1–3 days
after viral infection.
The 1st symptom noted is frequently sore or “scratchy” throat,
followed closely by nasal obstruction and rhinorrhea. Cough is
associated with ≈30% of colds and usually begins after the onset
of nasal symptoms. The usual cold persists for about 1 wk.,
although 10% last for 2 wk.
A change in the color or consistency of the secretions is common
during the course of the illness and is not indicative of sinusitis or
bacterial super infection.
TREATMENT
The management of the common cold consists primarily of
symptomatic treatment.
COMPLICATIONS:
• Otitis media.
• Sinusitis.
• Exacerbations of asthma.
Adenoidal and Tonsillar Hypertrophy
• The most common cause of chronic upper airway
obstruction in children is hypertrophy of the adenoids
and tonsils. The adenoids are lymphoid tissue arising
from the posterior and superior walls of the
nasopharynx in the region of the choanae. Adenoid
and tonsillar hyperplasia may be aggravated by
recurrent infection, allergy, and inhaled irritants.
Clinical Manifestations:
• Mouth breathing.
• Snoring.
• In some patients, obstructive sleep apnea.
• Recurrent
or persistent otitis media, because the
eustachian tubes enter the nasopharynx at the choanae
and can be obstructed by enlarged adenoids.
Diagnostic Studies:
• Adenoidal
hypertrophy is assessed by a lateral
radiograph of the nasopharynx or by flexible
nasopharyngoscopy.
Treatment
• If the adenoids or tonsils are large and thought to be
significantly contributing to upper airway obstruction, then the
most effective treatment is removal.
• Because the adenoids are not a discrete organ but rather
consist of lymphoid tissue, regrowth after adenoidectomy is
possible.
• If the tonsils are large and the obstruction is severe, then
removing the tonsils in addition to the adenoids may be
necessary.
Acute Pharyngitis & Tonsillitis
Etiology
• Viruses: (adenoviruses, coronaviruses, enteroviruses,
rhinoviruses, respiratory syncytial virus [RSV], Epstein-Barr
virus [EBV], herpes simplex virus [HSV],) .
• Bacteria : (GABHS)
CLINICAL MANIFESTATIONS
• Streptococcal pharyngitis: onset is often rapid with
prominent sore throat, fever, and absence of cough.
Headache and gastrointestinal symptoms (abdominal pain,
vomiting) are frequent. The pharynx is red, and the tonsils
are enlarged and classically covered with a yellow, bloodtinged exudate. There may be petechiae on the soft palate
and posterior pharynx, and the uvula may be red, and
swollen. The anterior cervical lymph nodes are enlarged
and tender. The incubation period is 2–5 days. Some
patients demonstrate the additional stigmata of scarlet
fever.
• Viral pharyngitis: onset is more gradual, and
symptoms more often include rhinorrhea, cough, and
diarrhea. A viral etiology is suggested by the presence of
conjunctivitis, coryza, hoarseness, and cough.
Diagnosis
The goal of specific diagnosis is to identify GABHS infection
• Throat culture.
• Antistreptococcal antibodies.
Treatment
• Early antibiotic therapy hastens clinical recovery by 12–24 hr .
•
•
•
•
The primary benefit of treatment is the prevention of acute
rheumatic fever, which is almost completely successful if antibiotic
treatment is instituted within 9 days of illness.
Penicillin V: given bid or tid for 10 days: 250 mg/dose for children and
500 mg/dose for adolescents and adults.
Oral amoxicillin: once-daily 50mg/kg dose of amoxicillin given orally
for 10 days.
Single intramuscular dose of benzathine penicillin (600,000 U for
children <27 kg [60 lb]; 1.2 million U for larger children and adults)
ensures compliance and provides adequate blood levels for more
than 10 days.
Erythromycin: 40 mg/kg/day divided bid, tid, or qid orally for 10 days
is recommended for patients allergic to β-lactam antibiotics .
Complications and Prognosis :
• Viral: otitis media.
• GABHS:
• Early local suppuration (e.g. parapharyngeal abscess).
• Late non suppurative (RF&GN)
Choanal Stenosis (Atresia)
• Choanal stenosis/atresia is a congenital problem that presents
•
•
•
•
in the neonatal period. It may be bilateral or unilateral and is a
relatively rare cause of respiratory distress in newborns.
Neonates are generally obligate nose breathers, so obstruction
of nasal passages can cause significant respiratory distress.
Inability to easily pass a small catheter through the nostrils
should raise the suspicion of choanal atresia.
The diagnosis is confirmed by CT scan and by inspecting the
area directly with a flexible nasopharyngoscope.
An oral airway may be useful in the short term, but the
definitive treatment is surgery
Acute Epiglottitis
• It is a medical emergency because of the risk of
sudden supraglottic airway obstruction.
• This illness is now rare and usually caused by group
A streptococcal or staphylococcus aureus infections
or H. influenza type B in unimmunized patients.
Clinical Manifestation
• Characterized by an acute rapidly progressive course.
• Often, the otherwise healthy child suddenly develops a sore throat and
•
•
•
•
•
fever. Within a matter of hours, the patient appears toxic, swallowing is
difficult, and breathing is labored.
Drooling is usually present and the neck is hyperextended in an
attempt to maintain the airway. The patients typically have a preference
for sitting, often with the head held forward, the mouth open, and the
jaw thrust forward (sniffing position).
A brief period of air hunger with restlessness may be followed by
rapidly increasing cyanosis and coma.
Stridor is a late finding and suggests near-complete airway
obstruction.
Complete obstruction of the airway and death can ensue unless
adequate treatment is provided.
The barking cough typical of croup is rare. Usually, no other family
members are ill with acute respiratory symptoms.
Diagnosis
• Lateral radiograph reveals thickened and bulging epiglottis (thumb
sign) and swelling of the aryepiglottic folds.
• Anxiety-provoking interventions such as phlebotomy, intravenous
line placement, placing the child supine, or direct inspection of the
oral cavity should be avoided until the airway is secure.
• The diagnosis is confirmed by direct observation of the inflamed
and swollen supraglottic structures and swollen, cherry-red
epiglottitis, which should be performed only in prepared operating
room to place an endotracheal tube or perform a tracheostomy if
needed.
Treatment
• Antibiotic therapy: as 3rd generation cephalosporine &
chloramphenicol.
• Endotracheal intubation: to maintain the airway. Clinical
recovery is rapid, and most children can be extubated safely
within 48 to 72 hours.
Croup (Laryngotracheobronchitis)
• Croup, or laryngotracheobronchitis, is the most common
infection of the middle respiratory tract.
• The most common causes of croup are parainfluenza viruses
(types 1, 2, and 3) and respiratory syncytial virus.
• Croup is most common in children 6 months to 3 years of age,
with a peak in fall and early winter. It typically follows a
common cold.
CLINICAL MANIFESTATIONS
• The manifestations of croup are a harsh barking cough,
hoarseness, inspiratory stridor, low-grade fever,
respiratory distress that may develop slowly or quickly.
and
• Signs of upper airway obstruction, such as labored breathing
and marked suprasternal, intercostal,
retractions, may be evident on examination.
and
subcostal
• Wheezing may be present if there is associated lower airway
involvement.
LABORATORY AND IMAGING STUDIES
• Anteroposterior radiographs of the neck show the
diagnostic subglottic narrowing of croup known as
the steeple sign.
• Many rapid tests (PCR or antigen) are available for
parainfluenza viruses and RSV.
PA view of the upper airway shows the so-called steeple sign, the
tapered narrowing of the immediate subglottic airway (arrows)
TREATMENT
• Oral or intramuscular dexamethasone reduces symptoms, the
need for hospitalization, and shortens hospital stays.
Dexamethasone phosphate (0.6 to 1 mg/kg) may be given
once intramuscularly or dexamethasone (0.6 to 1 mg/kg) once
orally. Alternatively, prednisolone (2 mg/kg per day) may be
given orally in two to three divided doses.
• For
significant airway compromise, administration of
aerosolized racemic epinephrine reduces subglottic edema
by vasoconstriction, temporarily producing marked clinical
improvement. Aerosol treatment may need to be repeated
every 20 minutes (for no more than 1 to 2 hours) in severe
cases.
• Children should be kept as calm as possible to minimize
forceful inspiration. One useful calming method is for a child
with croup to sit in the parent's lap. Sedatives should be used
cautiously and only in the intensive care unit. Cool mist
administered by face mask may help prevent drying of the
secretions around the larynx.
• Hospitalization is often required for:
o Children with stridor at rest.
o Children receiving aerosol treatment should be hospitalized or observed
for at least 2 to 3 hours because of the risk of rebound airway obstruction.
Bacterial Tracheitis
• It is a rare but serious superinfection of the trachea
that may follow viral croup and is most commonly
caused by S. aureus.
Laryngomalacia (Floppy Larynx)
• Laryngomalacia is most common cause of stridor in infants. It is
due to exaggerated collapse of the glottic structures, especially the
epiglottis and arytenoid cartilages, during inspiration, but its precise
cause is not known.
• It may be due to decreased muscular tone of the larynx and
surrounding structures or to immature cartilaginous structures.
• Inspiratory stridor beginning at or shortly after birth should raise the
suspicion of laryngomalacia. It usually does not result in much
respiratory distress, but occasionally it is severe enough to cause
hypoventilation (CO2 retention), hypoxemia, and difficulty with
feeding.
Clinical Manifestations
• The primary sign of laryngomalacia is inspiratory
stridor with little to no expiratory component. The
stridor is typically loudest when the infant is feeding
or active and decreases when the infant is relaxed,
supine, or the neck is flexed. Exacerbated by viral
respiratory infections & GERD.
• Laryngomalacia normally peaks by 3 to 5 months of
age and resolves between 6 and 12 months of age.
Diagnostic Studies
• In typical cases, no need for investigation.
• In severe or atypical cases, the patient should undergo
flexible nasopharyngoscopy/laryngoscopy to assess the
patency and dynamic movement (collapse) of the larynx
and surrounding structures.
Treatment
• In most cases, no therapy is required for laryngomalacia. The
infant should be observed closely during times of respiratory
infection for evidence of respiratory compromise, although
most infants with laryngomalacia tolerate infections fairly well.
• Infants
with severe laryngomalacia that results in
hypoventilation, hypoxia, or growth failure may benefit from a
surgical procedure (aryoepiglottoplasty) or, in extreme cases, a
tracheostomy to bypass the upper airway.
Subglottic Stenosis
• Subglottic stenosis is the narrowing of trachea
immediately below the vocal cords.
• It may be:
• Congenital
• Acquired:
due to prolonged
endotracheal intubation.
or
repeated
Clinical Manifestations
• Subglottic stenosis can present as stridor that is frequently
biphasic (on both expiration and inspiration). However, the
stridor is usually more prominent on inspiration.
• Subglottic stenosis may also be associated with a barky cough
similar to that noted with croup.
• Respiratory
infections can cause subglottic edema,
exacerbating the clinical manifestations of subglottic stenosis.
Diagnostic Studies
• Definitive
diagnosis requires endoscopic evaluation,
either by flexible or rigid bronchoscopy.
Treatment
• Mild subglottic stenosis can be managed conservatively and
may improve sufficiently with airway growth alone.
• Severe cases require surgical intervention.
Others causes of UAO
• hemangioma, usually presents before 6 months of age. The
treatment of hemangiomas is controversial, but laser therapy and
corticosteroids (both direct injection and systemic) have been used
with moderate success. If the obstruction is severe, tracheostomy
tube is needed.
• Juvenile laryngeal papillomatosis .
• Vocal Cord Paralysis, Paralysis may be unilateral or bilateral and is
more often caused by damage to the recurrent laryngeal nerve than
by a central lesion. Peripheral nerve injury can be caused by trauma
(neck traction during delivery of infants or thoracic surgical
procedures). Central causes as hydrocephalus.
• Foreign body, should considered in any infant or child capable of
ingesting small objects who develops acute onset of stridor.
Differentiating Supraglottic from Subglottic Causes of Airway Obstruction