Use of continuous positive airway pressure (CPAP) in acute viral bronchiolitis: a systematic review

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.

High-flow nasal cannula therapy for infants with bronchiolitis

BACKGROUND

Bronchiolitis is a common lower respiratory tract illness, usually of viral aetiology, affecting infants younger than 24 months of age and is a frequent cause of hospitalisation. It causes airway inflammation, mucus production and mucous plugging, resulting in airway obstruction. Effective pharmacotherapy is lacking and bronchiolitis is a major cause of morbidity and mortality.Conventional treatment consists of supportive therapy in the form of fluids, supplemental oxygen and respiratory support. Traditionally oxygen delivery is as a dry gas at 100% concentration via low-flow nasal prongs. However, the use of heated, humidified, high-flow nasal cannula (HFNC) therapy enables delivery of higher inspired gas flows of an air/oxygen blend, up to 12 L/min in infants and 30 L/min in children. Its use provides some level of continuous positive airway pressure to improve ventilation in a minimally invasive manner. This may reduce the need for invasive respiratory support thus potentially lowering costs, with clinical advantages and fewer adverse effects.

OBJECTIVES

To assess the effects of HFNC therapy compared with conventional respiratory support in the treatment of infants with bronchiolitis.

SEARCH METHODS

We searched CENTRAL (2013, Issue 4), MEDLINE (1946 to May week 1, 2013), EMBASE (January 2010 to May 2013), CINAHL (1981 to May 2013), LILACS (1982 to May 2013) and Web of Science (1985 to May 2013). In addition we consulted ongoing trial registers and experts in the field to identify ongoing studies, checked reference lists of relevant articles and searched conference abstracts.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs which assessed the effects of HFNC (delivering oxygen or oxygen/room air blend at flow rates greater than 4 L/min) compared to conventional treatment in infants (< 24 months) with a clinical diagnosis of bronchiolitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently used a standard template to assess trials for inclusion and extract data on study characteristics, 'Risk of bias' elements and outcomes. We contacted trial authors to request missing data. Outcome measures included the need for invasive respiratory support and time until discharge, clinical severity measures, oxygen saturation, duration of oxygen therapy and adverse events.

MAIN RESULTS

We included one RCT which was a pilot study with 19 participants that compared HFNC therapy with oxygen delivery via a head box. In this study, we judged the risk of selection, attrition and reporting bias to be low, and we judged the risk of performance and detection bias to be unclear due to lack of blinding. The median oxygen saturation (SpO2) was higher in the HFNC group at eight hours (100% versus 96%, P = 0.04) and at 12 hours (99% versus 96%, P = 0.04) but similar at 24 hours. There was no clear evidence of a difference in total duration of oxygen therapy, time to discharge or total length of stay between groups. No adverse events were reported in either group and no participants in either group required further respiratory support. Five ongoing trials were identified but no data were available in May 2013. We were not able to perform a meta-analysis.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine the effectiveness of HFNC therapy for treating infants with bronchiolitis. The current evidence in this review is of low quality, from one small study with uncertainty about the estimates of effect and an unclear risk of performance and detection bias. The included study provides some indication that HFNC therapy is feasible and well tolerated. Further research is required to determine the role of HFNC in the management of bronchiolitis in infants. The results of the ongoing studies identified will contribute to the evidence in future updates of this review.

Virale Infektionen: RNA-Viren

Rhinoviren sind die Haupterreger der sog. Erkältungskrankheiten. Eine wichtige Rolle spielen sie auch als Auslöser von Asthmaattacken.

Es findet eine stete Kozirkulation mehrerer Serotypen statt, im gemäßigten Klima gibt es Herbst-, Winter- und Frühjahrsepidemien, die Übertragung geschieht weit häufiger über infizierte Sekrete als durch Aerosole.

Rhinoviren gehören zu den Picornaviren. Rhinoviren sind sehr kleine Viren mit einem positiven Einzelstrang-RNA-Genom ohne Lipidhülle und daher gegen Detergens enthaltende Desinfektionsmittel sehr resistent. Sie sind empfindlich gegen Umgebungs-pH außerhalb des Bereichs 5,0–7,5.

Zurzeit bilden sie zusammen mit den Enteroviren das Genus Enterovirus der Picornaviren. Serologisch lassen sich über 100 Typen unterscheiden. Kennzeichnend ist die Bindungsfähigkeit an das von den meisten Rhinoviren für die Zelladsorption genützte ICAM-1 (interzelluläres Adhäsionsmolekül).

Nach einer Inkubationszeit von 1–3 Tagen tritt Schnupfen auf, die höchste Viruskonzentration im Nasensekret nach 2–4 Tagen, wiederum nach 2–4 Tagen bei disponierten Patienten auch bronchiale Obstruktion. Es konnte gezeigt werden, dass zu dieser Zeit auch Virus-RNA im Bronchialepithel vorhanden ist. Die postinfektiöse bronchiale Hyperreagibilität korreliert mit der Dauer des Virus-RNA-Nachweises im Nasopharynx. Die Immunität ist im Wesentlichen abhängig von der nur sehr kurzen Anwesenheit sekretorischer spezifischer IgA-Antikörper. Die bei den Serotypen beobachtbare Kreuzreaktivität spiegelt sich nicht in Kreuzimmunität wider.

Infants with severe respiratory syncytial virus needed less ventilator time with nasal continuous airways pressure then invasive mechanical ventilation

AIM

Nasal continuous positive airway pressure (NCPAP) has been proposed as an early first-line support for infants with severe respiratory syncytial virus (RSV) infection. We hypothesised that infants <6 months with severe RSV would require shorter ventilator support on NCPAP than invasive mechanical ventilation (IMV).

METHODS

Retrospective cohort analysis of infants admitted to two paediatric intensive care units, one primarily using NCPAP and one exclusively using IMV, between January 2008 and February 2010.

RESULTS

We studied 133 (NCPAP n = 89, IMV n = 46) consecutively admitted infants. On admission, disease severity [i.e. Paediatric RISk of Mortality (PRISM) II score (NCPAP 5.1 ± 2.8 vs. IMV 12.2 ± 6.0, p < 0.001) and SpO2 /Fi O2 ratio (NCPAP 309 ± 81 vs. IMV 135 ± 98, p < 0.001)] was higher in the IMV group. NCPAP remained independently associated with shorter ventilatory support (hazard ratio 2.3, 95% CI 1.1-4.7, p = 0.022) after adjusting for PRISM II score, PCO2 , SpO2 /Fi O2 ratio, bronchopulmonary dysplasia and occurrence of clinically suspected secondary bacterial pneumonia.

CONCLUSION

Nasal continuous positive airway pressure was independently associated with a shorter duration of ventilatory support. Differences in baseline disease severity mandate a randomised trial before the routine use of NCPAP can be recommended.

High-flow nasal cannula oxygen for bronchiolitis in a pediatric ward: a pilot study

High-flow nasal cannula (HFNC) is a widely used ventilatory support in children with bronchiolitis in the intensive care setting. No data is available on HFNC use in the general pediatric ward. The aim of this study was to evaluate the feasibility of HFNC oxygen therapy in infants hospitalized in a pediatric ward for moderate-severe bronchiolitis and to assess the changes in ventilatory parameters before and after starting HFNC support. This prospective observational pilot study was carried out during the bronchiolitis season 2011-2012 in a pediatric tertiary care academic center in Italy. Interruptions of HFNC therapy and possible side effects or escalation to other forms of respiratory support were recorded. Oxygen saturation (SpO2), end-tidal carbon dioxide (ETCO2), and respiratory rate (RR), measured for a baseline period of 1 h before and at specific time intervals in 48 h after the start of HFNC were recorded. Twenty-seven infants were included (median age 1.3 months; absolute range 0.3-8.5). No adverse events, no premature HFNC therapy termination, and no escalation to other forms of respiratory support were recorded. Median SpO2 significantly increased by 1-2 points after changing from standard oxygen to HFNC (p <0.001). Median ETCO2 and RR rapidly decreased by 6-8 mmHg and 13-20 breaths per minute, respectively, in the first 3 h of HFNC therapy (p <0.001) and remained steady thereafter.

CONCLUSIONS

Use of HFNC for oxygen administration is feasible for infants with moderate-severe bronchiolitis in a general pediatric ward. In these children, HFNC therapy improves oxygen saturation levels and seems to be associated with a decrease in both ETCO2 and RR.

Respiratory syncytial virus bronchiolitis in children

Respiratory syncytial virus is a highly infectious virus that commonly causes bronchiolitis and leads to high morbidity and a low, but important, incidence of mortality. Supportive therapy is the foundation of management. Hydration/nutrition and respiratory support are important evidence-based interventions. For children with severe disease, continuous positive airway pressure or mechanical ventilation may be necessary. Ribavirin may be used for treatment of patients with severe disease. Palivizumab provides important ongoing immunoprophylaxis during epidemic months for high-risk infants. Caregiver education and incorporating an explanation of all therapies and anticipatory guidance, including strategies for reducing the risk of infection, are vital.

Pathophysiology of Acute Respiratory Failure in Children with Bronchiolitis and Effect of CPAP

Acute bronchiolitis is the most common lower respiratory tract infection (LRTI) during the first year of life. Respiratory syncytial virus (RSV) infection is the most prevalent virus found in these children, accounting for 60–80 % of cases. The rate of hospitalization is less than 2 %. Up to 8 % of those hospitalized require ventilatory support [1, 2].

Racemic adrenaline and inhalation strategies in acute bronchiolitis

BACKGROUND

Acute bronchiolitis in infants frequently results in hospitalization, but there is no established consensus on inhalation therapy--either the type of medication or the frequency of administration--that may be of value. We aimed to assess the effectiveness of inhaled racemic adrenaline as compared with inhaled saline and the strategy for frequency of inhalation (on demand vs. fixed schedule) in infants hospitalized with acute bronchiolitis.

METHODS

In this eight-center, randomized, double-blind trial with a 2-by-2 factorial design, we compared inhaled racemic adrenaline with inhaled saline and on-demand inhalation with fixed-schedule inhalation (up to every 2 hours) in infants (<12 months of age) with moderate-to-severe acute bronchiolitis. An overall clinical score of 4 or higher (on a scale of 0 to 10, with higher scores indicating more severe illness) was required for study inclusion. Any use of oxygen therapy, nasogastric-tube feeding, or ventilatory support was recorded. The primary outcome was the length of the hospital stay, with analyses conducted according to the intention-to-treat principle.

RESULTS

The mean age of the 404 infants included in the study was 4.2 months, and 59.4% were boys. Length of stay, use of oxygen supplementation, nasogastric-tube feeding, ventilatory support, and relative improvement in the clinical score from baseline (preinhalation) were similar in the infants treated with inhaled racemic adrenaline and those treated with inhaled saline (P>0.1 for all comparisons). On-demand inhalation, as compared with fixed-schedule inhalation, was associated with a significantly shorter estimated mean length of stay--47.6 hours (95% confidence interval [CI], 30.6 to 64.6) versus 61.3 hours (95% CI, 45.4 to 77.2; P=0.01) - as well as less use of oxygen supplementation (in 38.3% of infants vs. 48.7%, P=0.04), less use of ventilatory support (in 4.0% vs. 10.8%, P=0.01), and fewer inhalation treatments (12.0 vs. 17.0, P<0.001).

CONCLUSIONS

In the treatment of acute bronchiolitis in infants, inhaled racemic adrenaline is not more effective than inhaled saline. However, the strategy of inhalation on demand appears to be superior to that of inhalation on a fixed schedule. (Funded by Medicines for Children; ClinicalTrials.gov number, NCT00817466; EudraCT number, 2009-012667-34.).

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.

6 cmH2O continuous positive airway pressure versus conventional oxygen therapy in severe viral bronchiolitis: a randomized trial

OBJECTIVE

To compare the effects of nasal continuous positive airway pressure (nCPAP) and conventional oxygen therapy on the clinical signs of respiratory distress and the respiratory muscle workload in acute viral bronchiolitis.

DESIGN

Prospective, randomized, monocentric study carried out in the pediatric intensive care unit (PICU) of a university hospital.

PATIENTS

Infants <6 months old, admitted to the PICU with severe respiratory syncytial virus bronchiolitis.

INTERVENTION

The patients were randomized into two groups for 6 hr. The nCPAP group (n = 10) received 6 cmH(2)O pressure support delivered by a jet flow generator and the control group (n = 9) received an air/oxygen mixture from a heated humidifier. Respiratory distress was assessed by the modified Wood's clinical asthma score (m-WCAS), and inspiratory muscle work was evaluated by calculating the pressure-time product per breath (PTP(insp) /breath) and per minute (PTP(insp) /min) from the esophageal pressure (Pes) recordings.

MEASUREMENTS AND MAIN RESULTS

Compared with control condition, nCPAP decreased m-WCAS [-2.4 (1.05) vs. -0.5 (1.3), P = 0.03], PTPes(insp)/breath [-9.7 (5.7) vs. -1.4 (8.2), P = 0.04], PTPes(insp) /min [-666 (402) vs. -116 (352), P = 0.015], and FiO(2) [-7 (10) vs. +5 (15), P = 0.05]. Significant worsening of m-WCAS was only observed in the control group (4/9 vs. 0/10, P = 0.03).

CONCLUSIONS

nCPAP rapidly decreased inspiratory work in young infants with acute bronchiolitis. Improvement in the respiratory distress score at 6 hr was proportional to the initial clinical severity, suggesting the importance of rapid nCPAP initiation in the more severe forms of the disease.