BRONCHIOLITIS

ACUTE Viral BRONCHIOLITIS Common disease of the lower respiratory tracr in infants.usually most cases < 2 years. Inflammatory obstruction of small airways. Severe disease more in infants 1-3 months of age. Seasonal peak in winter-early spring.

Etiolog- - - Epidemiology Predominantly viral . RSV>50% of cases Others parainfluenza, adenovirus,mycoplasma . No evidence for bacterial etilogy. Incidenceincreased over last decade ( incresed day-care centers, criteria for admissions,improved survival of PM infants at risk for RSV associated disease. Males>females ,not breast fed , living in crowded conditions. Older family members common source

Pathophysiology Not all infected hosts develop LRTI,(anatomic,immunologic factors) RSV initiate coplex immune response (eosinophil activation release of cationic proteins cytotoxic to airway epith.,IgE release,chemokines ILK-8,macrophage inflam. Prt. ,interferon -alpha ) Bronchial obstruction (edema,mucus,cellular debris),increase airway resistance(inverse proportion top 4th power of radius). Impaired gas exchange ( Hypoxemia) V/Q mismatch, if severe latehypercapnia )

CLINICAL MANIFESTATION Mild URTI (sneezing ,clear rhinorrhea, Diminished appetite Fever 38.5-39*C Gradual respiratory distress ;paroxysmal wheezy cough,dyspnea,irritability, tachypnea interferes with feedeing. Apnea may be more prominent than wheese in very young infants P/E :prominent wheese ,tachypnea(don,t correlate with hyopxemia,hypercarbia) increased work of breathing ,nasal flaring ,retraction Chest: fine crackles or wheezes.prolonged exp. Phase,hyperinflation of lungs

Labs; CXR: hyperinflation ,patchy atelectasis CBC : usually normal , Viral testing is debatable(rapid immunoflourescence,PCR, culture) Dx clinical DDx : - bronchial asthma , first episode two indistinguishable(repeated episodes ,absence pf viral prodrome,family hx of atopy/asthma) -foreign body aspiration –trachiobronchomalacia –vascular rings –CHF –CF - pertussis

Course- Prognosis First 48-72 hr :most critical (highest risk for respioratory compromise Mortality <1% due to apnea ,uncompensated repiratory acidosis , severe dehydration Higher morbidity mortality in infants with underlying disease(immune deficiencies, CHF, BPD )

Recurrent wheezing after bronchiolitis ;higher incidence of asthma and wheezing in children with hx of bronchiolitis,unexplained by family hx/atopy

Treatment Hospitalization ,for children with respiratory distress If hypoxic ( cool humidified oxygen) avoid sedatives ..child sitting with head and chest elevated 30 degree angle with neck extended . feeding ;due to high risk of aspiration of oral food with tachypnea and increased work of breathing infants may be fed by NG tube, or if more distress kept NPO with IVF. Adjuvant therapy ,Bronchodilators ;modest short term improvement of clinical feature ( nebulized epinephrine vs salbitamol),trail dose of bronchodilators ,further therapy according to response.

Corticosteroids ,oral ,inhaled ,parenteral :widely used despite conflicting studies.(not indicated ; risks outweigh theoretical benefit) Ribavarin ,administered by aerosal used as antiviral therapy with CHD and chronic lung disease Antibiotic ,no role unless secondary bacterial infx. RSV immunoglobulins ,no support to be beneficial.

PREVENTION High risk patients to prevent severe RSV disease :(RSV-IVIG) ,IM monoclonal antibodies (palivizumab) : premature babies ,patients less than two yearss with chronic lung disease) Meticulous hand washing to prevent nosocomial infx..