Respiratory infections Dr. 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 bronchi intrapulmonary airway is within the lung parenchyma

SIGN EXTRATHORACI C AIRWAY OBSTRUCTION INTRATHORACI C- EXTRAPULMON ARY AIRWAY OBSTRUCTION INTRAPULMON ARY 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 epigl ottis

Treatment;  1-Endotracheal intubation is the preferred method of treatment. most patient can be safely extubated with in 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 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 RSV it 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