Steroid Therapy in Acute Bronchiolitis A New Old Line of Therapy.

Bronchiolitis is an acute lower respiratory tract infection in early childhood.A subcommittee of the American Academy of Pediatrics (AAP) together with the European Respiratory Society (ERS) underlined that is a clinical diagnosis, recognized as "a constellation of clinical symptoms and signs including a viral upper respiratory prodrome followed by increased respiratory effort and wheezing in children less than 2 years of age".

Bronchiolitis is the common reason for hospitalization of children in many countries, challenging both economy, area and staffing in pediatric departments. A substantial proportion of children will experience at least one episode with bronchiolitis, and as much as 2-3% of all children will be hospitalized with bronchiolitis during their first year of life. Bronchiolitis is the most common medical reason for admission of children to intensive care units (ICU) particularly those with risk Factors will have a severe course of bronchiolitis, providing challenges regarding ventilation, fluid balance and general support This may be a particular challenge for ICUs without a specialized pediatric section.

Many respiratory viruses have been associated with acute viral bronchiolitis although Respiratory Syncytial Virus (RSV) remains the most common identified virus causing bronchiolitis, occurring in epidemics during winter months.The infection starts in the upper respiratory tract, spreading to the lower airways within few days.The inflammation in the bronchioles is characterized by a peri-bronchial infiltration of white blood cell types, mostly mono nuclear cells, and oedema of the submucosa and adventitia. Damage may occur by a direct viral injury to the respiratory airway epithelium, or indirectly by activating immune responses. Oedema, mucus secretion, and damage of airway epithelium with necrosis may cause partial or total airflow obstruction, distal air trapping, atelectasis and a ventilation perfusion mismatch leading to hypoxemia and increased work of breathing. Smooth-muscle constriction seems to play a minor role in the pathologic process of bronchiolitis.

Risk factors for bronchiolitis are male gender, a history of prematurity, young age, being born in relation to the RSV season, pre-existing disease such as broncho pulmonary- dysplasia , underlying chronic lung disease , neuromuscular disease, congenital heart- disease , exposure to environmental tobacco smoke , high parity, young maternal age, short duration/no breast feeding , maternal asthma and poor socioeconomic factors.

Bronchiolitis often starts with rhinorrhoea and fever, thereafter gradually increasing with signs of a lower respiratory tract infection including tachypnoea, wheezing and cough. Very young children, particularly those with a history of prematurity, may appear with apnea as their major symptom.Feeding problems are common.

On clinical examination, the major finding in the youngest children may be fine inspiratory crackles on auscultation, whereas high-pitched expiratory wheeze may be prominent in older children. By observation, the infants may have increased respiratory rate, chest movements, prolonged expiration, recessions, use of accessory muscles, cyanosis and decreased general condition.

No routine laboratory or radio graphic diagnostic tests for bronchiolitis except for pulse oxymetry , have been shown to have a substantial impact on the clinical course of bron- chiolitis , and recent guidelines and evidence-based reviews recommend that no diagnostic tests are used routinely.

The present study describes the efficacy of steroid therapy in patients with acute bronchiolitis. Theoretically, corticosteroid, an anti-inflammatory agent, should be helpful in the treatment of bronchiolitis because airway inflammation and edema are the main pathophysiologies. Recent evidence has shown elevation of interleukins and other inflammatory mediators in the respiratory tracts of children with acute bronchiolitis. Eosinophil cationic protein, implicated in the pathogenesis of asthma, was found to have a significant role in RSV bronchiolitis. Most of these mediators could be found during the period of virus replication.The clinical effect of dexamethasone, with a long half -life of 36-72 hr, may peak after 3-4 hr of treatment. Corticosteroids widely used in different routes in the treatment of acute bronchiolitis:

Dexamethasone injection used in hospitalized children with acute bronchiolitis showed significantly reduction in the mean respiratory distress duration, mean duration of oxygen therapy and the mean length of hospital stay.

Oral dexamethasone used in pediatric out patients with acute bronchiolitis produced demonstrable clinical improvement in the initial 4 hr of treatment and reduced the hospitalization rate.

Corticosteroid inhalation therapy used in RSV- bronchiolitis showed evidence of prolonged positive effects in reduction of the incidence of subsequent respiratory symptoms in the near future. However, the best and sufficient length of the treatment period, as well as the dose of the inhaled steroid, need to be determined..

Fluticasone propionate, a potent corticosteroid, has been demonstrated in vitro to inhibit virus-induced chemokine production by airway cells in patients infected with Respiratory Syncytial Virus. However, the inhibition was found to take at least 48 hr to reach its full effect.