Respiratory infectionsDr. Tara Husain

airway is divided into 3 anatomic parts

extrathoracic airway ; from the nose to the thoracic inlet

intrathoracic-extrapulmonary airway ; from the thoracic inlet to the main stem bronchiintrapulmonary airway is within the lung parenchyma

SIGNEXTRATHORACIC AIRWAY OBSTRUCTION

INTRATHORACIC-EXTRAPULMONARY AIRWAY OBSTRUCTION

INTRAPULMONARY AIRWAY OBSTRUCTION

PARENCHYMAL PATHOLOGY

Tachypnea + + ++ ++++

Retractions ++++ ++ ++ +++

Stridor ++++ ++ − −

Wheezing ? +++ ++++ ?

Grunting ? ? ++ ++++

Cough; results from stimulation of irritant receptors located in the airway mucosa including the ear

Causes of Acute Cough; Acute respiratory infection. pulmonary edema. chemical irritation. Foreign body aspiration

Causes of chronic cough; Allergy ( asthma, allergic rhinitis) Anatomical abnormality ( tracheo-

esophageal fistula, Gastroesophageal reflux).

Chronic infection; cystic fibrosis Immunodeficiency. Environmental exposure Ticks.

Croup (Laryngotracheobronchitis) It is acute infectious

laryngotrachiobronchitits. parainfluenza virus type 1 and 2 are the

most common agents Usually affects children between6 months-

3 years,

Clinical presentation; starts by symptoms of upper respiratory tract

infection(common cold) , then a brassy cough typically sounding like a

barking seal Then inspiratory stridor and respiratory distress Symptoms are characteristically worse at night and

often recur with decreasing intensity, until about 1 wk

Most cases are mild and self limited, Rarely there may be very sever airway obstruction

necessitating artificial airway

Examination; suprasternal, intercostal and

subcostal retractions,. There may also be associated lower

airway obstruction manifested by wheeze or expiratory rhonchi

PA XR ; (Steeple) sign of narrowed subglottic space.

Treatment; Aerosolized raceme epinephrine reduces

edema temporarily(about 2 hours), in sever cases it may need to be repeated every 20 minutes. A case needing this treatment needs hospital admission

Corticosteroids ; systemic or inhaled dexamethasone (0.15 mg/kg) single dose helium-oxygen mixture (Heliox) may be

effective in children with severe croup for whom intubation is being considered

Antibiotics not indicated Over the counter cold medication not

indicated

Indications for hospital admission; progressive stridor severe stridor at rest respiratory distress hypoxia Cyanosis depressed mental status poor oral intake need for reliable observation

Epiglottitis Pediatric emergency inflammation of the epiglottis and/or the

supraglottic tissues surrounding the epiglottis predominantly bacterial ( H. influenzae type b).

Usually in children between 2-7 years otolaryngologist or general surgeon and

anesthesiologist should be consulted

Clinical presentation; sudden onset high fever Respiratory distress fulminate progression sever dysphagia and a muffled

voice Patients usually sit erect and they

may drool from there mouth because of dysphagia

Diagnosis; Thumb sign on lateral neck x-ray

differentiates epiglottitis from sever croup

Laryngoscope examination to inspect the epiglottis which shows cherry red enlargement

Blood culture and culture from the surface of the epiglottis

Treatment; 1-Endotracheal intubation is the preferred method of

treatment. most patient can be safely extubated with in 48-72 hours

Antibiotics ( ceftriaxon) should be given. All patients should receive oxygen unless the mask

causes excessive agitation Racemic epinephrine and corticosteroids are

ineffective Minor procedures, such as intravenous access, may

cause respiratory distress and can be performed more safely after intubation

Examination of the tonsills by toungue depresser is contraindicated unless in operative theater

Bronchiolitis; Is predominantly a viral disease. RSV is responsible for >50% of cases Other agents include parainfluenza adenovirus, Mycoplasma. occur in winter or early spring Older family members are a common source of

infection; they might only experience minor upper respiratory symptoms (colds)

Host anatomic and immunologic factors play a significant role in the severity

Co-infection with >1 virus can also alter the clinical manifestations and/or severity of presentation

Clinical presentation; rhinorrhea, cough, and low grade fever, followed in several days with the onset

of rapid breathing and wheezing. The child may feed poorly and may

have sleeping disturbance. Acute symptoms last for 5-6 days, recovery is complete usually after 10-

14 days

Examination;

dyspnea, intercostal and subcostal

retraction, Tachypnea prolonged expiratory phase, in very sever cases there may be

cyanosis

Differential diagnosis; Congenital malformations; vascular

ring, left ventricular enlargment, intrinsic abnormality

Foreign body aspiration Gastroesophageal reflux Trauma; aspirations, burns, or scalds of

the tracheobronchial tree tumors

Diagnosis; CXR; typically shows air trapping and

may show peribronchial, thickening, there may be atelectasis, or infiltrates

WBC count is usually normal RSV may be isolated from nasopharyngeal

secretions by PCR,culture Hypoxemia may occur secondary to

ventilation perfusion mismatch. Hypercapnia is rare occurring in severely

affected infants with sever airway obstruction and respiratory fatigued

Treatment; Oxygen; Humidified oxygen should be given to

maintain oxygen saturation of more than 93%. Bronchodilators; such as aerosolized beta

agonist or racemic epinephrine may be beneficial in selected patients

Corticosteroids; offer little benefit. Antibiotics; are not indicated unless there is

evidence of secondary bacterial infection Ribavirin aerosol; a specific antiviral agent

RSVit has been demonstrated to be mildly effective. It is considered in patients with high risk disease

Mechanical ventilation; required to treat respiratory failure or apnea.

monthly injections of RSV monoclonal antibodies for infants and toddlers under 2 years with bronchopulmonary dysplasia

Supportive measures; Intravenous fluid, if there is poor oral intake