Non-invasive positive pressure ventilation for acute asthma in children

Review question

We reviewed available evidence on non-invasive positive pressure ventilation (NPPV) for children with acute asthma.

Background

Asthma is known to cause acute exacerbations, in which characteristic changes in the lungs predispose to respiratory difficulties and in some cases respiratory failure. This condition constitutes a significant economic burden and a major health issue worldwide. Evidence supporting this intervention has been considered weak, and the intervention is not recommended in clinical guidelines. Nevertheless, use of NPPV in the care of children with acute asthma has increased, and NPPV might be an effective intervention for acute asthma. Until now, no systematic review has summed up all the evidence provided by randomised clinical trials.

Study characteristics

The evidence is current to August 2016. We included two trials, with 40 participants. Included trials assessed the effects of one type of NPPV called bilevel positive airway pressure, which lasted for two and 24 hours, respectively, in the two trials.

Key results

Overall, we found that NPPV compared with no additional treatment, treatment as usual or placebo did not result in any benefit or harm regarding death from all causes, serious adverse events (i.e. major complications) or improvement in asthma symptoms. Five study participants did not tolerate the treatment, four because of discomfort and one because intubation was required. Current evidence cannot confirm or reject the effects of NPPV for treatment of children with acute asthma. Larger randomised clinical trials are warranted.

Quality of the evidence

The evidence behind our conclusions is of very low quality. The two studies had high risk of bias (i.e. the studies were conducted in a way that may skew results to the positive side). In addition, the two studies included few participants, making results of this review imprecise.

Authors' conclusions: 

Current evidence does not permit confirmation or rejection of the effects of NPPV for acute asthma in children. Large RCTs with low risk of bias are warranted.

Read the full abstract...
Background: 

Asthma is one of the most common reasons for hospital admission among children and constitutes a significant economic burden. Use of non-invasive positive pressure ventilation (NPPV) in the care of children with acute asthma has increased even though evidence supporting the intervention has been considered weak and clinical guidelines do not recommend the intervention. NPPV might be an effective intervention for acute asthma, but no systematic review has been conducted to assess the effects of NPPV as an add-on therapy to usual care in children with acute asthma.

Objectives: 

To assess the benefits and harms of NPPV as an add-on therapy to usual care (e.g. bronchodilators and corticosteroids) in children with acute asthma.

Search strategy: 

We identified trials from the Cochrane Airways Group Specialised Register (CAGR). The Register contains trial reports identified through systematic searches of bibliographic databases, including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, AMED and PsycINFO, and by handsearching of respiratory journals and meeting abstracts. We also conducted a search of ClinicalTrials.gov (www.ClinicalTrials.gov) and the WHO trials portal (www.who.int/ictrp/en/). We searched all databases from their inception to February 2016, with no restriction on language of publication.

Selection criteria: 

We included randomised clinical trials (RCTs) assessing NPPV as add-on therapy to usual care versus usual care for children (age < 18 years) hospitalised for an acute asthma attack.

Data collection and analysis: 

Two review authors independently screened titles and abstracts. We retrieved all relevant full-text study reports, independently screened the full text, identified trials for inclusion and identified and recorded reasons for exclusion of ineligible trials. We resolved disagreements through discussion or, if required, consulted a third review author. We recorded the selection process in sufficient detail to complete a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) flow diagram and 'Characteristics of excluded studies' table. We identified the risk of bias of included studies to reduce the risk of systematic error. We contacted relevant study authors when data were missing.

Main results: 

We included two RCTs that randomised 20 participants to NPPV and 20 participants to control. We assessed both studies as having high risk of bias; both trials assessed effects of bilateral positive airway pressure (BiPAP). Neither trial used continuous positive airway pressure (CPAP). Controls received standard care. Investigators reported no deaths and no serious adverse events (Grades of Recommendation, Assessment, Development and Evaluation (GRADE): very low quality of evidence due to serious risk of bias and serious imprecision of results). Both trials showed a statistically significant reduction in symptom score. One trial did not report a standard deviation (SD), but by using an estimated SD, we found a statistically significantly reduced asthma symptom score (mean difference (MD) -2.50, 95% confidence interval (CI) -4.70 to -0.30, P = 0.03, 19 participants, GRADE: very low quality of evidence). In the other trial, NPPV was associated with a lower total symptom score (5.6 vs 1.9, 16 participants, very low quality of evidence) before cross-over, but investigators did not report an SD, nor could it be estimated from the first phase of the trial, before the cross-over. These gains could be clinically relevant, as a reduction of three or more points in symptom score is considered a clinically meaningful change. Researchers documented five dropouts (12.5%), four of which were due to intolerance to NPPV, and one to respiratory failure requiring intubation. Owing to insufficient reporting in the latter trial and use of different scoring systems, it was not possible to conduct a meta-analysis nor a Trial Sequential Analysis.

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