Dr.Mai Mohamed Elhassan Mustafa Assistant Professor

Lower Respiratory Tract Infections

objectives

By the end of this lecture each student should be able to;

¨  Diagnose and manage Acute Bronchiolitis ¨  Diagnose and manage pneumonia and relate the

age to the suspected organism.

Definition

¨  Lower respiratory tract infections is a term used to describe any infection below the vocal cords.

include : ¨  Pneumonia ¨  Bronchitis ¨  Bronchiolitis ¨  Laryngotracheobronchitis (croup)

Definition

-Acute infectious inflammation of the bronchioles resulting in wheezing and airways obstruction in children less than 2 y e a r s o l d .

-It is caused by Respiratory Syncytial V i r u s R S V

PATHOGENESIS

§  Bronchiolar cell necrosis, ciliary

disruption, peribronchial lymphocytic infiltration

§  Edema, excessive mucus, sloughed epithelium lead to airway obstruction & atelectasis

CLINICAL FEATURES/symptoms

§  Begin with upper respiratory tract symptoms: nasal congestion, rhino rhea, mild cough, low-grade fever.

Progress in 3-6 days to : §  rapid respirations, §  chest retractions §  wheezing.

CLINICAL FEATURES/signs

§  Tachypnea +/_ signs of respiratory distress §  Rhonchi, wheezes +/- crackles. §  Possible dehydration §  Possible conjunctivitis or otitis media §  Possible cyanosis or apnea

RISK FACTORS for SEVERITY

Ø Prematurity Ø Low birth weight Ø Age less than 12

weeks Ø Chronic pulmonary

disease

Ø Neurologic disease Ø Anatomical defects of

the airways Ø  significant cardiac

disease Ø  Immunodeficiency

DIFFERENTIAL DIAGNOSIS §  Asthma §  Bronchitis §  pneumonia §  Chronic lung disease §  Aspiration pneumonia §  Congenital heart disease or heart failure

DIAGNOSIS

§  Clinical diagnosis based on history and physical examination.

§  WBC count normal §  Supported by CXR findings: hyperinflation

COURCE

§  Usually self-limiting. Indication for hospitalization §  Children with severe disease. §  Toxic with poor feeding, lethargy, dehydration. §  Apnea §  Hypoxemia §  Parent unable to care for child at home.

TREATMENT

Ø  Ist 48_96hr higher risk for repiratory compromised

Out lines of treatment: Ø  Supportive care

Ø  Frequent monitoring - HR, RR and oxygen saturation . Ø  Arterial Blood gases if in ICU or has severe distress.

TREATMENT

Ø  Supportive treatment Ø  Oxygen to maintain saturations > 92% Ø  IV fluids –if dehydrated or less feeding. Ø  Antipyretics---if febrile. Ø  Mechanical ventilation---if indicated. Ø  CORTICOSTERIODS- Not recommended may be

helpful in children with chronic lung disease.

TREATMENT

Ø  RIBAVIRINMay be useful in infants with confirmed RSV at risk for more severe disease.

Ø  ANTIBIOTICS - Not useful

Prevention --PALIVIZUMAB Monoclonal antibody against RSV indicated in infants less than 2years with;

1.  Prematurity 2.  Chronic lung disease 3.  Congenital heart disease

COMPLICATIONS

¨  Apnea ¨  Respiratory failure ¨  secondary bacterial infection

§  Case fatality rate less than 1%.

§  Higher morbidity and mortality in infants with

CHD ,immunodeficiency and bronchopulmonary dysplasia.

Pneumonia

¨  Inflammation of lung parenchyma CAUSES

¨  Infectious ; microorganisms ¨  Noninfectious causes:

¤ Aspiration of food or gastric acid ¤ Foreign bodies ¤ Hydrocarbons, and lipoid substances ¤ Hypersensitivity reactions ¤ Drug- or radiation-induced pneumonitis

Epidemiology

¨  Significant cause of mortality in children < 5years age .

¨  ~4 million deaths worldwide/year* ¨  Reduction after introduction of congugate

pneumococcal and Hib vaccine.

Etiology

¨  Bacterial pneumonia

¨  Viral pneumonia ¤  Predominant cause in infants and children younger than 5 yr

of age ¤  Peak attack rate for viral pneumonia is between the ages of

2 and 3 yr ¤  Influenza and RSV, especially in children younger than 3 yr

of age ¤  others, Para influenza viruses, rhinoviruses , and

adenoviruses.

RISK FACTORS

¨  Specific risk factors:

¤ Lung disease ( cystic fibrosis)

¤ Anatomic problems (tracheoesophageal fistula)

¤ Gastro esophageal reflux with aspiration

¤ Neurologic disorders with decreased protection of the

airway or compromised clearing of the airway

¤ Altered immune system

Classification

Recent 1.Community-acquired pneumonia (CAP) is infectious pneumonia in a person who has not

recently been hospitalized. CAP is the most common type of pneumonia. The most common causes of CAP vary depending on a

person's age, 2.Hospital-acquired pneumonia ¨  Also called nosocomial pneumonia,

Causes of Community-Acquired Pneumonia by Age Group

Age Common causes

Less than one Month bacterial Group B streptococci Escherichia coli

S. pneumoniae

1 month to 3 months Viruses, bacterial •  S. pneumoniae , H. influenzae type B •  Chlamydia trachomatis,M. pneumoniae,

3 months to12 months

Viruses,

bacterial ( S. pneumoniae ,H. influenzae type B) Chlamydia trachomatis, M. pneumoniae, Group A streptococus

2 to 5 years Viruses,

bacterial S. pneumoniae , H. influenzae type B Chlamydia trachomatis,M. pneumoniae, s. aureus,Group A streptococus

5 to 18 years M. pneumoniae, S. pneumoniae, C. pneumoniae H. influenzae type B. and viruses

Pathogenesis

¨ Viral pneumonia ¤ From spread of infection along the airways ¤ Direct injury of the respiratory epithelium ¤ Results:

n Airway obstruction from swelling n Abnormal secretions n Cellular debris n Significant hypoxemia

¤ Predisposed to secondary bacterial infection

Pathogenesis

q  Bacterial pneumonia

-Pathology varies according to organism

q  Mycoplasma. pneumonia

n Attaches to the respiratory epithelium

n  Inhibits ciliary action

n  Leads to cellular destruction

Pathogenesis

¨  Bacterial Infections ¤ S. pneumoniae

n Edema that aids in the proliferation of organisms and spread into adjacent portions of lung

n Resulting in the characteristic focal lobar involvement

¤ Group A Streptococcus n More diffuse infection with interstitial pneumonia n Necrosis of tracheobronchial mucosa n  Large amounts of exudate, edema, and hemorrhage n  Involvement of lymphatic vessels n  Increased likelihood of pleural involvement

Pathogenesis

¨  S. aureus pneumonia

¤ Often unilateral

¤ Extensive areas of hemorrhagic necrosis

¤  Irregular areas of cavitation of the parenchyma

n Pneumatoceles

n Empyema

n Bronchopulmonary fistulas.

Clinical Manifestations

¨  Most often preceded by URTI (rhinitis and cough) ¨  Fever - lower in viral pneumonia ¨  Tachypnea (constant sign) ¨  Increased work of breathing. ¨  Signs of severe infection (cyanosis , respiratory

fatigue, especially in infants) ¤  Crackles and wheezing ¤  Signs of consolidation

Clinical Manifestations

¨  Bacterial pneumonia in older children

¤  Brief upper respiratory tract illness

¤  Followed by the abrupt onset of chills and high fever

¤  Drowsiness with intermittent periods of restlessness

¤  Rapid respirations

¤  Cough

¤  Chest pain

¤  Anxiety

Clinical Manifestations

¨  Physical findings depend on the stage of pneumonia ¤ Early in the course:

n Diminished breath sounds n Scattered crackles, and rhonchi

¤  Increasing consolidation n Dullness on percussion is noted n Breath sounds are markedly diminished n Abdominal distention - swallowed air or ileus n  Liver may seem enlarged n Nuchal rigidity, in the absence of meningitis - right upper Lobe involvement.

Clinical presentation

¨  Some infants with bacterial pneumonia may have associated vomiting, anorexia and abdominal distention

Diagnosis

¨  Depends on history &physical examination. ¨  Definitive diagnosis based on viral and bacterial

cultures Ø  Viral: isolated from secretions

Ø  Bacterial: Pleural fluid, Blood (10-30% positive, pneumococcal)

Ø  ASO titers – group A strep

Ø  Mycoplasma – cold agglutins (non-specific)

Diagnosis

¨  White blood cell (WBC) count can be helpful ¤ Viral: decreased, normal or elevated

n Usually not higher than 20,000/mm3 n  Lymphocyte predominance n Adenovirus, may not follow this pattern

¤ Bacterial: elevated WBC count n 15,000–40,000/mm3 n Predominance of granulocytes

Diagnosis

¨  Chest radiograph confirms the diagnosis and detect complication e.g. pleural effusion and empyema.

¨  In general, viral pneumonia: ¤ Hyperinflation with bilateral interstitial infiltrates

¨  Lobar consolidation is typically seen with pneumococcal pneumonia

¨  Radiographic appearance alone is not diagnostic and other clinical features must be considered

Upper lobar

¨  R. middle lobe ¨  Bronchopneumonia

Pneumonia----indication for admission

¨  Age < 6 month ¨  Sickle cell anemia with acute chest syndrome ¨  Toxic appearance ¨  Vomiting, dehydration ¨  Toxic appearance ¨  Immunocompromised state ¨  Multiple lobe involvement ¨  Requirements of supplemental oxygen ¨  No response to appropriate oral antibiotics

Treatment—bacterial pneumonia

Antibiotics Specific treatment depends on causative organism and clinical

appearance ,If mildly ill Out patient; §  preschool age -------- oral amoxicillin

§  School age (atypical)------------ macrolid (azithromycin)

§  Adolescent ---------- flurorquinolone

Hospitalized cases

Approach based on the clinical manifestation at

presentation:

If suspected bacterial pneumonia parenteral antibiotics

(cephalosporins)

-If diagnosis suggest staphylococcal pneumonia add

vancomycin or clindamycin

Complications

¤  Pleural effusion ¤  Empyema ¤  Pericarditis

¨  Bacteremia and hematologic spread ¨  Rare complications of pneumococcal and H.Influenzae

type b infection ¤  Meningitis ¤  Suppurative arthritis ¤  Osteomyelitis

Recurrent Pneumonias? q  Defined as two or more episode in a single year or

three or more episode ever with radiographic clearing in between.

causes §  Disorders of Immunity §  Anatomical disorders. §  Foreign Body

THANKS