Recombinant Human Deoxyribonuclease in Infants With Respiratory Syncytial Virus Bronchiolitis

Prevention and Treatment Strategies for Respiratory Syncytial Virus (RSV)

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract disease, especially in young children. Despite its global impact on healthcare, related to its high prevalence and its association with significant morbidity, the current therapy is still mostly supportive. Moreover, while more than 50 years have passed since the first trial of an RSV vaccine (which unfortunately caused enhanced RSV disease), no vaccine has been approved for RSV prevention. In the last two decades, our understanding of the pathogenesis and immunopathology of RSV have continued to evolve, leading to significant advancements in RSV prevention strategies. These include both the development of new potential vaccines and the successful implementation of passive immunization, which, together, will provide coverage from infancy to old age. In this review, we provide an update of the current treatment options for acute disease (RSV-specific and -non-specific) and different therapeutic approaches focusing on RSV prevention.

[Possibilities of using recombinant human deoxyribonuclease I in otorhinolaryngology]

ANNOTATION

Dornase alfa (Pulmozyme, Tigerase) is a purified solution of recombinant human DNase, clinically developed for the treatment of pulmonary diseases in patients with cystic fibrosis (CF). The action of the drug is aimed at destroying the viscous secretion, rich in DNA strands of neutrophils, through their fragmentation, the density of the secretion decreases, and the aeration of the lower respiratory tract improves. The similarity of pathological processes with the formation of viscous exudate on the surface of the mucous membrane in diseases of the upper respiratory tract and ear initiated studies on the use of Dornase alpha in otorhinolaryngology.

MATERIAL AND METHODS

The analysis of materials of domestic and foreign authors on the effectiveness of the use of the drug Dornase alfa in otorhinolaryngology was carried out.

RESULTS

The review included 132 patients (10 studies) in whom Dornase alfa was used to treat CF-associated nasal and paranasal sinus diseases. Analysis of the literature revealed only 3 studies, one of which consisted of two parts, examining the effect of Dornase alpha on middle ear exudate: two studies were demonstrated in an animal model; one - in vitro on samples of middle ear effusion which were aspirated through a myringotomy incision from patients with recurrent acute otitis media; and one in clinical 40 patients (40 ears) for hydrolysis of exudate in the tympanostomy tubes.

CONCLUSION

Analysis of studies on the use of Dornase alfa demonstrates an improvement in clinical symptoms in all patients with CF and chronic rhinosinusitis. In experimental studies on an animal model, as well as in vitro research on exudate from the middle ear, Dornase alfa has demonstrated high efficacy and safety. Dornase alfa is a drug with high potential, further research is needed for wider use in ENT practice, especially in otiatrics.

Serine proteases in neutrophil extracellular traps exhibit anti-Respiratory Syncytial Virus activity

Human respiratory syncytial virus (hRSV) is an infectious agent in infants and young children which there are no vaccines or drugs for treatment. Neutrophils are recruited for airway, where they are stimulated by hRSV to release large amounts of neutrophil extracellular traps (NETs). NETs are compound by DNA and proteins, including microbicidal enzymes. They constitute a large part of the mucus accumulated in the lung of patients, compromising their breathing capacity. In contrast, NETs can capture/inactivate hRSV, but the molecules responsible for this effect are unknown.

OBJECTIVES

We selected microbicidal NET enzymes (elastase, myeloperoxidase, cathepsin-G, and proteinase-3) to assess their anti-hRSV role.

METHODS AND RESULTS

Through in vitro assays using HEp-2 cells, we observed that elastase, proteinase-3, and cathepsin-G, but not myeloperoxidase, showed virucidal effects even at non-cytotoxic concentrations. Elastase and proteinase-3, but not cathepsin-G, cleaved viral F-protein, which is responsible for viral adhesion and fusion with the target cells. Molecular docking analysis indicated the interaction of these macromolecules in the antigenic regions of F-protein through the active regions of the enzymes.

CONCLUSIONS

Serine proteases from NETs interact and inactive hRSV. These results contribute to the understanding the role of NETs in hRSV infection and to designing treatment strategies for the inflammatory process during respiratory infections.

Rational use of mucoactive medications to treat pediatric airway disease

Many airway diseases in children, notably bronchiolitis, cystic fibrosis (CF), non-CF bronchiectasis including primary ciliary dyskinesia, pneumonia, and severe asthma are associated with retention of airway secretions. Medications to improve secretions clearance, the mucoactive medications, are employed to treat these diseases with varying degrees of success. This manuscript reviews evidence for the use of these medications and future directions of study.

Recombinant Human Deoxyribonuclease I

Human deoxyribonuclease I (DNase I) is an endonuclease that catalyzes the hydrolysis of extracellular DNA and is just one of the numerous types of nucleases found in nature. The enzymatic mechanism for a single turnover is reasonably well understood based on biochemical and structural studies that are consistent with divalent metal ion dependent nonspecific nicking of a phosphodiester bond in one of the strands of double stranded DNA. Recombinant human DNase I (rhDNase I, rhDNase, Pulmozyme^®, dornase alfa) has been expressed in mammalian cell culture in Chinese hamster ovary cells and developed clinically where it is aerosolized into the airways for treatment of pulmonary disease in patients with cystic fibrosis (CF). rhDNase I hydrolyzes the DNA in purulent sputum of CF patients and reduces sputum viscoelasticity. Reduction of high molecular weight DNA into smaller fragments by treatment with aerosolized rhDNase I has been proposed as the mechanism to reduce the mucus viscosity and improve mucus clearability from obstructed airways in patients. The improved clearance of the purulent mucus enhances pulmonary function and reduces recurrent exacerbations of respiratory symptoms. rhDNase I was approved for clinical use in 1993 and has been widely used as a safe and effective therapy for CF patients. The use of rhDNase I has also been investigated in other diseases where exogenous DNA has been implicated in the disease pathology.

Bronchiolitis clinics and medical treatment

Bronchiolitis is the most common acute lower respiratory tract infection in infants and the first cause of hospitalization in this age group. Despite it has been studied for over 70 years, its management remains controversial and nowadays the treatment is only supportive. Pediatricians should be well acquainted with the clinical course of the disease. In particular, they should know that the severity of respiratory symptoms peaks between days 3-7 of the disease and dehydration is a key sign to consider for the management. In this review, we will discuss the most controversial points in the management of bronchiolitis according to six evidence-based guidelines, six clinical practice guidelines and five consensus-based reviews.

Bronchiolitis in children: The Saudi initiative of bronchiolitis diagnosis, management, and prevention (SIBRO)

Bronchiolitis is the leading cause of admissions in children less than two years of age. It has been recognized as highly debated for many decades. Despite the abundance of literature and the well-recognized importance of palivizumab in the high risk groups, and despite the existence of numerous, high-quality, recent guidelines on bronchiolitis, the number of admissions continues to increase. Only supportive therapy and few therapeutic interventions are evidence based and proved to be effective. Since Respiratory Syncytial Virus (RSV) is the major cause of bronchiolitis, we will focus on this virus mostly in high risk groups like the premature babies and children with chronic lung disease and cardiac abnormalities. Further, the prevention of RSV with palivizumab in the high risk groups is effective and well known since 1998; we will discuss the updated criteria for allocating infants to this treatment, as this medication is expensive and should be utilized in the best condition. Usually, diagnosis of bronchiolitis is not challenging, however there has been historically no universally accepted and validated scoring system to assess the severity of the condition. Severe RSV, especially in high risk children, is unique because it can cause serious respiratory sequelae. Currently there is no effective curative treatment for bronchiolitis. The utility of different therapeutic interventions is worth a discussion.

Recombinant Human Deoxyribonuclease Treatment in Hospital Management of Infants with Moderate-Severe Bronchiolitis

Bronchiolitis is the main cause of respiratory insufficiency in infants, characterized by acute inflammation, edema, necrosis of epithelial cells and increased mucus production. Mucus is mainly purulent and consequently rich in DNA, as derived from nuclei of degenerating neutrophils and epithelial debris. The treatment is mainly supportive; bronchodilators and systemic steroids are often used but do not reduce the length of hospital stay. The aim of our study is to evaluate the efficacy of recombinant human DNase (rhDNase), in infants affected by moderate-severe bronchiolitis. In a randomized double-blind placebo-controlled study, twenty-two infants (12 males) under 6 months of age (median age 1.6 months) were enrolled and randomly assigned to receive either nebulized rhDNase or placebo (saline) at a dose of 2.5 ml once a day for three days. All infants were evaluated, based on a clinical assessment score, on admission and four times daily during the hospitalization. Placebo and study groups were sex- and age-matched and were similar in terms of clinical severity on admission. No differences were observed between the two groups of patients with regard to the length of hospitalization and clinical score during the days observed. Two out of four infants, all in the study group, presenting atelectasis on chest radiographs, showed a rapid improvement on the first day. RhDNase is not an effective routine therapy in treating infants hospitalized for bronchiolitis and it is not useful in preventing severe forms of the disease. On the contrary, it may be an effective, safe and cost-benefit treatment only in infants with bronchiolitis and massive atelectasis.

Local dornase alfa treatment reduces NETs-induced airway obstruction during severe RSV infection

Respiratory syncytial virus (RSV) infection is characterised by airway obstruction with mucus plugs, containing DNA networks in the form of neutrophil extracellular traps (NETs). We investigated the effect of dornase alfa on histopathological NETs-induced airway obstruction and viral load in an age-relevant calf model of severe bovine RSV disease. As compared with the control animals, dornase alfa treatment resulted in a strong reduction of NETs-induced airway obstruction. Viral load in the lower respiratory tract was not different between the two groups. We conclude that NETs form a relevant target for treatment of airway obstruction in severe RSV disease.

Neutrophil Extracellular Traps in Respiratory Disease: guided anti-microbial traps or toxic webs?

Neutrophil recruitment to the airways and lungs is a major hallmark of many respiratory diseases. One of the more recently discovered unique innate immune effector mechanisms of neutrophils is the formation of neutrophil extracellular traps (NETs), consisting of an extracellular network of DNA fibers studded with nuclear and granule proteins. Although in the respiratory system NETs contribute to capture and inactivation of bacteria, fungi and viruses, there is a delicate 'balance' between aid and damage to the host. Accumulating evidence now suggests that NETs can have direct cytotoxic effects to lung epithelial and endothelial cells and can contribute to airway obstruction. As such, NETs may play an important role in the pathogenesis of respiratory diseases. The purpose of this review is to give an up-to-date overview of the current status of NETs in respiratory diseases. We examine both experimental and clinical data concerning the role of NETs in host defence as well as immunopathology, with special attention paid to the literature relevant for the paediatric pulmonology community. Finally, we discuss future treatment strategies that may target the formation of NETs in the airways and lungs.

Neutrophil Extracellular Traps in Pulmonary Diseases: Too Much of a Good Thing?

Neutrophil extracellular traps (NETs) arise from the release of granular and nuclear contents of neutrophils in the extracellular space in response to different classes of microorganisms, soluble factors, and host molecules. NETs are composed by decondensed chromatin fibers coated with antimicrobial granular and cytoplasmic proteins, such as myeloperoxidase, neutrophil elastase (NE), and α-defensins. Besides being expressed on NET fibers, NE and MPO also regulate NET formation. Furthermore, histone deimination by peptidylarginine deiminase 4 (PAD4) is a central step to NET formation. NET formation has been widely demonstrated to be an effective mechanism to fight against invading microorganisms, as deficiency in NET release or dismantling NET backbone by bacterial DNases renders the host susceptible to infections. Therefore, the primary role of NETs is to prevent microbial dissemination, avoiding overwhelming infections. However, an excess of NET formation has a dark side. The pathogenic role of NETs has been described for many human diseases, infectious and non-infectious. The detrimental effect of excessive NET release is particularly important to lung diseases, because NETs can expand more easily in the pulmonary alveoli, causing lung injury. Moreover, NETs and its associated molecules are able to directly induce epithelial and endothelial cell death. In this regard, massive NET formation has been reported in several pulmonary diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, respiratory syncytial virus bronchiolitis, influenza, bacterial pneumonia, and tuberculosis, among others. Thus, NET formation must be tightly regulated in order to avoid NET-mediated tissue damage. Recent development of therapies targeting NETs in pulmonary diseases includes DNA disintegration with recombinant human DNase, neutralization of NET proteins, with anti-histone antibodies and protease inhibitors. In this review, we summarize the recent knowledge on the pathophysiological role of NETs in pulmonary diseases as well as some experimental and clinical approaches to modulate their detrimental effects.

Neutrophil extracellular traps cause airway obstruction during respiratory syncytial virus disease

Human respiratory syncytial virus (RSV) is the most important cause of severe lower respiratory tract disease (LRTD) in young children worldwide. Extensive neutrophil accumulation in the lungs and occlusion of small airways by DNA-rich mucus plugs are characteristic features of severe RSV-LRTD. Activated neutrophils can release neutrophil extracellular traps (NETs), extracellular networks of DNA covered with antimicrobial proteins, as part of the first-line defence against pathogens. NETs can trap and eliminate microbes; however, abundant NET formation may also contribute to airway occlusion. In this study, we investigated whether NETs are induced by RSV and explored their potential anti-viral effect in vitro. Second, we studied NET formation in vivo during severe RSV-LRTD in infants and bovine RSV-LRTD in calves, by examining bronchoalveolar lavage fluid and lung tissue sections, respectively. NETs were visualized in lung cytology and tissue samples by DNA and immunostaining, using antibodies against citrullinated histone H3, elastase and myeloperoxidase. RSV was able to induce NET formation by human neutrophils in vitro. Furthermore, NETs were able to capture RSV, thereby precluding binding of viral particles to target cells and preventing infection. Evidence for the formation of NETs in the airways and lungs was confirmed in children with severe RSV-LRTD. Detailed histopathological examination of calves with RSV-LRTD showed extensive NET formation in dense plugs occluding the airways, either with or without captured viral antigen. Together, these results suggest that, although NETs trap viral particles, their exaggerated formation during severe RSV-LRTD contributes to airway obstruction.

Antibiotics for bronchiolitis in children under two years of age

BACKGROUND

Bronchiolitis is a serious, potentially life-threatening respiratory illness commonly affecting babies. It is often caused by respiratory syncytial virus (RSV). Antibiotics are not recommended for bronchiolitis unless there is concern about complications such as secondary bacterial pneumonia or respiratory failure. Nevertheless, they are often used.

OBJECTIVES

To evaluate the effectiveness of antibiotics for bronchiolitis in children under two years of age compared to placebo or other interventions.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2014, Issue 6), which includes the Cochrane Acute Respiratory Infection Group's Specialised Register, and the Database of Abstracts of Reviews of Effects, MEDLINE (1966 to June 2014), EMBASE (1990 to June 2014) and Current Contents (2001 to June 2014).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing antibiotics to placebo in children under two years diagnosed with bronchiolitis, using clinical criteria (including respiratory distress preceded by coryzal symptoms with or without fever). Primary clinical outcomes included time to resolution of signs or symptoms (pulmonary markers included respiratory distress, wheeze, crepitations, oxygen saturation and fever). Secondary outcomes included hospital admissions, length of hospital stay, readmissions, complications or adverse events and radiological findings.

DATA COLLECTION AND ANALYSIS

Two review authors independently analysed the search results.

MAIN RESULTS

We included seven studies with a total of 824 participants. The results of these seven included studies were often heterogeneous, which generally precluded meta-analysis, except for deaths, length of supplemental oxygen use and length of hospital admission.In this update, we included two new studies (281 participants), both comparing azithromycin with placebo. They found no significant difference for length of hospital stay, duration of oxygen requirement and readmission. These results were similar to an older study (52 participants) that demonstrated no significant difference comparing ampicillin and placebo for length of illness.One small study (21 participants) with higher risk of bias randomised children with proven RSV infection to clarithromycin or placebo and found a trend towards a reduction in hospital readmission with clarithromycin.The three studies providing adequate data for days of supplementary oxygen showed no difference between antibiotics and placebo (pooled mean difference (MD) (days) -0.20; 95% confidence interval (CI) -0.72 to 0.33). The three studies providing adequate data for length of hospital stay, similarly showed no difference between antibiotics (azithromycin) and placebo (pooled MD (days) -0.58; 95% CI -1.18 to 0.02).Two studies randomised children to intravenous ampicillin, oral erythromycin and control and found no difference for most symptom measures.There were no deaths reported in any of the arms of the seven included studies. No other adverse effects were reported.

AUTHORS' CONCLUSIONS

This review did not find sufficient evidence to support the use of antibiotics for bronchiolitis, although research may be justified to identify a subgroup of patients who may benefit from antibiotics. Further research may be better focused on determining the reasons that clinicians use antibiotics so readily for bronchiolitis, how to reduce their use and how to reduce clinician anxiety about not using antibiotics.

The effect of 3% and 6% hypertonic saline in viral bronchiolitis: a randomised controlled trial

Bronchiolitis is a common disorder in young children that often results in hospitalisation. Except for a possible effect of nebulised hypertonic saline (sodium chloride), no evidence-based therapy is available. This study investigated the efficacy of nebulised 3% and 6% hypertonic saline compared with 0.9% hypertonic saline in children hospitalised with viral bronchiolitis.

In this multicentre, double-blind, randomised, controlled trial, children hospitalised with acute viral bronchiolitis were randomised to receive either nebulised 3%, 6% hypertonic saline or 0.9% normal saline during their entire hospital stay. Salbutamol was added to counteract possible bronchial constriction. The primary endpoint was the length of hospital stay. Secondary outcomes were need for supplemental oxygen and tube feeding.

From the 292 children included in the study (median age 3.4 months), 247 completed the study. The median length of hospital stay did not differ between the groups: 69 h (interquartile range 57), 70 h (IQR 69) and 53 h (IQR 52), for 3% (n=84) and 6% (n=83) hypertonic saline and 0.9% (n=80) normal saline, respectively, (p=0.29). The need for supplemental oxygen or tube feeding did not differ significantly. Adverse effects were similar in the three groups.

Nebulisation with hypertonic saline (3% or 6% sodium chloride) although safe, did not reduce the length of stay in hospital, duration of supplemental oxygen or tube feeding in children hospitalised with moderate-to-severe viral bronchiolitis.

Acute bronchiolitis in infants, a review

Acute viral bronchiolitis is one of the most common medical emergency situations in infancy, and physicians caring for acutely ill children will regularly be faced with this condition. In this article we present a summary of the epidemiology, pathophysiology and diagnosis, and focus on guidelines for the treatment of bronchiolitis in infants. The cornerstones of the management of viral bronchiolitis are the administration of oxygen and appropriate fluid therapy, and overall a “minimal handling approach” is recommended. Inhaled adrenaline is commonly used in some countries, but the evidences are sparse. Recently, inhalation with hypertonic saline has been suggested as an optional treatment. When medical treatment fails to stabilize the infants, non-invasive and invasive ventilation may be necessary to prevent and support respiratory failure. It is important that relevant treatment algorithms exist, applicable to all levels of the treatment chain and reflecting local considerations and circumstances.

Bronchoscopic interventions with surfactant and recombinant human deoxyribonuclease for acute respiratory distress syndrome–type respiratory syncytial virus–pneumonia in moderately preterm infants: Case series

Atelectases, over-inflation of ventilated regions of the lung, and consecutive pneumothoraces are life-threatening conditions in mechanically ventilated infants with acute respiratory distress syndrome–type respiratory syncytial virus–pneumonia. The accumulation of viscous secretions secondary to impaired mucociliary clearance in the more proximal parts of the bronchial tree is the prerequisite for atelectases and also prevents the delivery of inhaled medications to the more distal parts of the lung. Herein, we describe four moderately premature infants with respiratory failure on mechanical ventilation, displaying a total of 20 radiologically verified new atelectases that were treated by bronchoscopic interventions with consecutive suctioning of secretions, restoration of the surfactant film within the airways, and deposition of recombinant human deoxyribonuclease at the first segment level of the bronchial tree. On 13 occasions (65%), resolution of atelectases was proven by chest X-ray and resulted in improved lung function. We conclude that these bronchoscopic interventions may contribute to the restoration of the gas exchange area in moderately premature infants with acute respiratory distress syndrome–type respiratory syncytial virus–pneumonia.

Viral bronchiolitis in children: a common condition with few therapeutic options

Even though bronchiolitis is a disease that has been recognized for many years, there are still few therapeutic strategies beyond supportive therapies. Bronchiolitis is the most frequent cause of hospital admission in children less than 1 year of age. The incidence is estimated to be about 150° million cases a year worldwide, and 2-3% of these cases require hospitalization. It is acknowledged that viruses cause bronchiolitis, but most of the studies focus on RSV. The RSV causes a more severe form of bronchiolitis in children with risk factors including prematurity, cardiovascular disease and immunodeficiency. Other viruses involved in causing bronchiolitis include RV, hMPV, hBoV and co-infections. The RV seems to be associated with a less severe acute disease, but there is a correlation between the early infection and subsequent wheezing bronchitis and asthma in later childhood and adulthood. The supportive therapies used are intravenous fluids and oxygen supplement administered by nasal cannula or CPAP in most complicated patients. Additional pharmacological therapies include epinephrine, 3% hypertonic saline and corticosteroids. The Epinephrine seems to have the greatest short-term benefits and reduces the need of hospital admission, whereas hypertonic saline and corticosteroids seem to reduce the length of hospital stay. As bronchiolitis is such a prevalent disease in children and RV seems to play an important role, perhaps more studies should center around the RV's contribution to the initial disease and following pathology.

Treatment of bronchiolitis: state of the art

Bronchiolitis is a leading cause of acute illness and hospitalization for infants and young children worldwide. It is usually a mild disease, but the few children developing severe symptoms need to be hospitalized and some will need ventilatory support. To date, the mainstay of therapy has been supportive care, i.e. assisted feeding and hydration, minimal handling, nasal suctioning and oxygen therapy. In recent years the delivery of oxygen has been improved by using a high-flow nasal cannula. At the same time, the discovery of nebulized hypertonic saline enables better airway cleaning with a benefit for respiratory function. The possible role of any pharmacological approach is still debated: many pharmacological therapies tried in the past, ranging from bronchodilators to corticosteroids, were found to offer no benefit in this disease. More recently, nebulized adrenaline demonstrated a short-term benefit. Prophylaxis and prevention, especially in children at high risk of severe infection, such as prematurely born infants and children with bronchopulmonary dysplasia, have a fundamental role in dealing with this disease. In this review, we focus on current recommendations for the management and prevention of bronchiolitis, paying particular attention to the latest literature in search of answers to the questions that remain open.

Nebulised deoxyribonuclease for viral bronchiolitis in children younger than 24 months

BACKGROUND

Bronchiolitis is one of the most common respiratory problems in the first year of life. The sputum of infants with bronchiolitis has increased deoxyribonucleic acid (DNA) content, leading to mucous plugging and airway obstruction. Recombinant human deoxyribonuclease (rhDNase), an enzyme that digests extracellular DNA, might aid the clearance of mucus and relieve peripheral airway obstruction.

OBJECTIVES

To determine the effect of nebulised rhDNase on the severity and duration of viral bronchiolitis in children younger than 24 months of age in the hospital setting.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2012, Issue 7 which includes the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to July Week 4, 2012), EMBASE (1974 to August 2012) and LILACS (1982 to August 2012).

SELECTION CRITERIA

Randomised controlled trials (RCTs) using nebulised rhDNase alone or with concomitant therapy in children younger than 24 months of age hospitalised with acute bronchiolitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed literature searches, assessed trial quality and extracted data. We obtained unpublished data from trial authors. We used Review Manager 5.1 to pool treatment effects expressed as the mean difference (MD) or standardised mean difference (SMD) with 95% confidence intervals (CI).

MAIN RESULTS

Three RCTs (333 participants) were identified, two of which were multicentre trials comprising only participants positive for respiratory syncytial virus (RSV). The other trial enrolled participants clinically diagnosed with bronchiolitis from a hospital in Italy. All studies used 2.5 mL (1 mg/mL) of nebulised rhDNase compared with placebo either as a daily or a twice daily dose. Adjunctive therapy included nebulised salbutamol, steroids, supplemental oxygen, intravenous fluids or tube feeding, nasal washing, nasal decongestants and antibiotics.Overall, nebulised rhDNase showed no benefit in clinically meaningful outcomes. Meta-analysis favoured the control group with a shorter duration of hospital stay (MD 0.50; 95% CI 0.10 to 0.90, P = 0.01) and better clinical score improvement (SMD -0.24; 95% CI -0.50 to 0.01, P = 0.06). The largest trial showed no difference in supplemental oxygen use or intensive care unit (ICU) admission.In one RCT, four out of 11 patients in the treatment group had atelectasis. Two of these patients showed distinctive clinical improvement after nebulised rhDNase.There was no significant difference in adverse events. These included temporary desaturation, temporary coughing, increased coughing, facial rash, hoarseness, dyspnoea and bad taste, reported in a total of 11 patients from both treatment groups.

AUTHORS' CONCLUSIONS

The results based on the three included studies in this review did not support the use of nebulised rhDNase in children under 24 months of age hospitalised with acute bronchiolitis. In these patients, treatment did not shorten the length of hospitalisation or improve clinical outcomes. It might have a role in severe bronchiolitis complicated by atelectasis, but further clinical studies would need to be performed.

Respiratory syncytial virus: diagnosis, treatment and prevention

Respiratory Syncytial Virus (RSV) is a common virus that infects children and adults; however, children younger than two years of age tend to develop more serious respiratory symptoms. RSV is responsible for thousands of outpatient visits (e.g., emergency room/primary care physician), hospitalizations and can result in death. Treatment is primarily supportive care and the illness resolves without complications in most children. RSV prophylaxis with palivizumab is an option for high-risk infants and children, which can decrease hospitalization and length of stay. Immunocompromised patients are a special population of which ribavirin and palivizumab may be used for treatment. Currently, no medication or vaccine available has been able to show a reduction in mortality from RSV. Future vaccines are in the developmental stage and will hopefully decrease the symptomatic and economic burden of this disease.

Endotracheal DNase for atelectasis in ventilated neonates

Management of atelectasis and lung collapse in ventilated neonates remains a common challenge in the neonatal intensive care unit. Recombinant human DNase (rhDNase) is an established treatment of atelectasis in cystic fibrosis and its use is also reported in the management of asthma, respiratory syncitial virus bronchiolitis and bronchiectasis to liquefy sputum and aid its clearance from the lungs. We report the use of rhDNase in a subgroup of ventilated neonates with severe end-stage respiratory failure and atelectasis. Three of the four patients showed clinical improvement. A previously undiagnosed lung anomaly was subsequently identified in the fourth patient. Future randomized studies could examine any potential benefits of this emerging therapy.

Care of infants and children with bronchiolitis: a systematic review

Bronchiolitis is the most frequent cause of hospitalization in the infant population. Management varies widely, and the efficacy of many routinely implemented therapies is not supported by evidence. The purpose of the systematic review was to identify the best evidence available regarding the care of infants and children with bronchiolitis. A two-phase literature search was performed, and 20 publications were appraised. An abundance of evidence regarding management of bronchiolitis was revealed resulting in numerous recommendations. Use of a clinical pathway is proposed as a possible solution for moving this evidence into practice.

Antibiotics for bronchiolitis in children

BACKGROUND

Bronchiolitis is a serious, potentially life-threatening respiratory illness commonly affecting babies. It is often caused by respiratory syncytial virus (RSV). Antibiotics are not recommended for bronchiolitis unless there is concern about complications such as secondary bacterial pneumonia or respiratory failure. Nevertheless, they are used at rates of 34% to 99% in uncomplicated cases.

OBJECTIVES

To evaluate the effectiveness of antibiotics for bronchiolitis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2010, issue 4), which includes the Cochrane Acute Respiratory Infection Group's Specialised Register, and the Database of Abstracts of Reviews of Effects, MEDLINE (January 1966 to November 2010), EMBASE (1990 to December 2010) and Current Contents (2001 to December 2010).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing antibiotics to placebo in children under two years diagnosed with bronchiolitis, using clinical criteria (including respiratory distress preceded by coryzal symptoms with or without fever). Primary clinical outcomes included time to resolution of signs or symptoms (pulmonary markers included respiratory distress, wheeze, crepitations, oxygen saturation and fever). Secondary outcomes included hospital admissions, length of hospital stay, re-admissions, complications or adverse events and radiological findings.

DATA COLLECTION AND ANALYSIS

Two review authors independently analysed the search results.

MAIN RESULTS

Five studies (543 participants) met our inclusion criteria. One study randomised 52 children to either ampicillin or placebo and found no significant difference between the two groups for length of illness. A small study (21 children) with higher risk of potential bias randomised children with proven RSV infection to clarithromycin or placebo and found clarithromycin may reduce hospital re-admission (8% antibiotics versus 44% placebo; Fishers exact; P = 0.081). The two studies (267 children) providing adequate data for length of hospital stay showed no difference between antibiotics and control (pooled mean difference 0.34; 95% CI -0.71 to 1.38). Two studies randomised children to intravenous ampicillin, oral erythromycin and control and found no difference for most symptom measures. None of the trials reported deaths.

AUTHORS' CONCLUSIONS

This review found minimal evidence to support the use of antibiotics for bronchiolitis. Research to identify a possible small subgroup of patients who have complications from bronchiolitis such as respiratory failure and who may benefit from antibiotics is justified.

Respiratory syncytial virus prevention and therapy: past, present, and future

Respiratory syncytial virus (RSV) is the most common respiratory pathogen in infants and young children worldwide. More than 50 years after its discovery, and despite relentless attempts to identify pharmacological therapies to improve the clinical course and outcomes of this disease, the most effective therapy remains supportive care. Although the quest for a safe and effective vaccine remains unsuccessful, pediatricians practicing during the past decade have been able to protect at least the more vulnerable patients with safe and effective passive prophylaxis. This review summarizes the history, microbiology, epidemiology, pathophysiology, and clinical manifestations of this infection in order to provide the reader with the background information necessary to fully appreciate the many challenges presented by the clinical management of young children with bronchiolitis. The last part of this article attempts an evidence-based review of the pharmacologic strategies currently available and those being evaluated, intentionally omitting highly experimental approaches not yet tested in clinical trials and, therefore, not likely to become available in the foreseeable future.

Update on management of bronchiolitis

PURPOSE OF REVIEW

Bronchiolitis impacts millions of infants worldwide. Although several therapeutic options stem from highly plausible theoretical rationales for success and some may even offer modest short-term symptom relief, none has been conclusively shown to alter the course of the disease or its major outcomes. However, several recent papers shed light on which treatments show promising preliminary evidence and offer insight into future research endeavors on this topic. This review will summarize bronchiolitis therapy in view of this recent evidence.

RECENT FINDINGS

The agents in which theory promises but treatment does not deliver include systemic corticosteroids alone, inhaled bronchodilators alone and antileukotrienes. The most promising combination to date appears to be that of oral dexamethasone and inhaled epinephrine but numerous related issues need to be clarified further. Caretakers need to be counselled about the usual protracted clinical course of bronchiolitis.

SUMMARY

Because bronchiolitis is a highly heterogeneous entity, future research challenges should include detailed characterization of infants most likely to benefit from given interventions. In the meantime, stick with the good old time-honored supportive route!

Current therapies in bronchiolitis

Viral bronchiolitis is the most common cause of hospitalization among infants. Despite its prevalence, no consistently effective therapy has been found to date, providing the driving force behind much of the ongoing research into this illness. In this review, we present a summary of the most recent published trials of interventions for bronchiolitis. Included are studies evaluating bronchodilators, corticosteroids, positive pressure ventilation, as well as 3 newer therapies for bronchiolitis: heliox, mucolytics, and leukotriene receptor antagonists.

Respiratory viral infections in infants: causes, clinical symptoms, virology, and immunology

In global terms, respiratory viral infection is a major cause of morbidity and mortality. Infancy, in particular, is a time of increased disease susceptibility and severity. Early-life viral infection causes acute illness and can be associated with the development of wheezing and asthma in later life. The most commonly detected viruses are respiratory syncytial virus (RSV), rhinovirus (RV), and influenza virus. In this review we explore the complete picture from epidemiology and virology to clinical impact and immunology. Three striking aspects emerge. The first is the degree of similarity: although the infecting viruses are all different, the clinical outcome, viral evasion strategies, immune response, and long-term sequelae share many common features. The second is the interplay between the infant immune system and viral infection: the immaturity of the infant immune system alters the outcome of viral infection, but at the same time, viral infection shapes the development of the infant immune system and its future responses. Finally, both the virus and the immune response contribute to damage to the lungs and subsequent disease, and therefore, any prevention or treatment needs to address both of these factors.

Recombinant human DNase in children with airway malacia and lower respiratory tract infection

BACKGROUND

Children with airway malacia often have protracted courses of airway infections, because dynamic airway collapse during coughing results in impaired mucociliary clearance. The aim of this study was to determine the effect of the mucolytic drug recombinant human deoxyribonuclease (rhDNase) on the recovery of respiratory symptoms in children with airway malacia and lower respiratory tract infection (LRTI).

METHODS

In a randomized double-blind controlled clinical trial, 40 children with airway malacia and LRTI were randomly assigned to receive either 2.5 mg nebulized rhDNase or placebo twice daily for 2 weeks. The primary endpoint was the change in the cough diary score (CDS) (scale 0-5) from baseline to the second week of treatment. Secondary endpoints were VAS symptom scores for cough, dyspnea, and difficulty in expectorating sputum, need for an antibiotic course, and lung function data (FVC, FEV(1), FEF(75), R(int(e))).

RESULTS

There was no significant difference in the mean change in CDSs from baseline between the rhDNase group and the placebo group (mean difference for daytime 0.19 (95% CI -0.53 to 0.90); for nighttime 0.38 (95% CI -0.30 to 1.05). Proportions of patients requiring antibiotics, and the mean changes in symptom scores and lung function from baseline did not significantly differ between both groups.

CONCLUSION

Treatment with 2 weeks of nebulized rhDNase does not enhance recovery or reduce the need for antibiotics in children with airway malacia and LRTI. (Controlled-trials.com number, ISRCTN85366144).

Heliox reduces respiratory system resistance in respiratory syncytial virus induced respiratory failure

INTRODUCTION

Respiratory syncytial virus (RSV) lower respiratory tract disease is characterised by narrowing of the airways resulting in increased airway resistance, air-trapping and respiratory acidosis. These problems might be overcome using helium-oxygen gas mixture. However, the effect of mechanical ventilation with heliox in these patients is unclear. The objective of this prospective cross-over study was to determine the effects of mechanical ventilation with heliox 60/40 versus conventional gas on respiratory system resistance, air-trapping and CO2 removal.

METHODS

Mechanically ventilated, sedated and paralyzed infants with proven RSV were enrolled within 24 hours after paediatric intensive care unit (PICU)admission. At T = 0, respiratory system mechanics including respiratory system compliance and resistance, and peak expiratory flow rate were measured with the AVEA ventilator. The measurements were repeated at each interval (after 30 minutes of ventilation with heliox, after 30 minutes of ventilation with nitrox and again after 30 minutes of ventilation with heliox). Indices of gas exchange (ventilation and oxygenation index) were calculated at each interval. Air-trapping (defined by relative change in end-expiratory lung volume) was determined by electrical impedance tomography (EIT) at each interval.

RESULTS

Thirteen infants were enrolled. In nine, EIT measurements were performed. Mechanical ventilation with heliox significantly decreased respiratory system resistance. This was not accompanied by an improved CO2 elimination, decreased peak expiratory flow rate or decreased end-expiratory lung volume. Importantly, oxygenation remained unaltered throughout the experimental protocol.

CONCLUSIONS

Respiratory system resistance is significantly decreased by mechanical ventilation with heliox (ISCRTN98152468).

Pharmacotherapy of impaired mucociliary clearance in non-CF pediatric lung disease. A review of the literature

Mucoactive agents are used to treat a variety of lung diseases involving impaired mucociliary clearance or mucus hypersecretion. The mucoactive agents studied most frequently are N-acetylcysteine (NAC), recombinant human DNase (rhDNase), and hypertonic saline. Studies on the efficacy of these have been mainly conducted in adults, and in patients with cystic fibrosis (CF). The exact role of mucoactive agents in children with non-CF lung disease is not well established. We present an overview of the current literature reporting clinical outcome measures of treatment with NAC, rhDNase, and hypertonic saline in children.