Is continuous positive airway pressure by helmet effective in the treatment of infants with bronchiolitis?

BEEM Bottom Line

Why is this study important?

Bronchiolitis caused by respiratory syncytial virus (RSV) is a common cause of emergency department (ED) visits among neonates and may result in acute respiratory failure. Continuous positive airway pressure (CPAP) is often used as first-line noninvasive respiratory support. However, it may not be well tolerated. This is the first study comparing helmet delivery of CPAP to the traditional face mask CPAP delivery in infants.

Which, if any, threats to validity are most likely to have an impact on the results and how?

Randomized controlled trials that are stopped early have been demonstrated to report implausibly large treatment effects favoring the intervention, particularly when the number of events is small.^[1] This trial is no different except that the statistically significant difference (p = 0.009) reported could not be reproduced from the outcome data reported.

How do the key results compare with the current evidence?

The current literature is quite limited but suggests that helmet delivery of CPAP is feasible and may be better tolerated than a traditional face mask.^[2]^[3] This study agrees with these conclusions; however, due to the small number of events, it does not provide enough evidence to conclude that helmet CPAP is superior to other delivery methods of CPAP.

How should this study impact the care of ED patients?

This study supports the feasibility of helmet-delivered CPAP, however, until more methodologically robust research is done, the evidence is insufficient to warrant a practice change away from the standard approach of face mask CPAP currently used across most healthcare facilities.

Study Summary

Pubmed ID

25780074

Study Reference

Chidini G, Piastra M, Marchesi T, et al. Continuous positive airway pressure with helmet versus mask in infants with bronchiolitis: an RCT. Pediatrics 2015;135:e868–75.

Study Design

Multicenter, nonblinded, randomized controlled trial.

Population

Included: Children (6–12 months old) with a diagnosis of RSV infection consistent with clinical features, positive nasopharyngeal swabs, and predefined acute respiratory failure admitted to 3 Italian pediatric intensive care units.

Excluded: Need for intubation; Glasgow Coma Scale score < 12; acidosis (pH < 7.25); cough or gag reflex impairment; upper airway obstruction; facial/gastric surgery; need for vasopressor or inotropes; enrollment in another study.

Intervention

Helmet CPAP in increasing from 4–10 cm H2O (by 2 cm H2O) to obtain pulse oxygen saturation ≥ 94% with fraction of inspired oxygen ≤ 0.6 continuously for 24 hours until oxygenation and clinical status improved.

Comparison

Face mask CPAP same as above.

Outcomes

Primary: Treatment failure defined as discontinuation of CPAP because of intolerance of or need for intubation. Intolerance was assessed using the Objective Pain Scale (OPS) and the COMFORT scale.

Secondary: CPAP application time; number of patients requiring sedation; and complications.

Key Results

N = 30 patients.

Sig.	Outcome	Outcome Helmet/Total vs. Outcome Face Mask/Total	NNT (95% CI)
NSS	Treatment failure	3/17 vs. 7/13	2.8 (1.5 to ∞)
SS	Requiring sedation	6/17 vs. 13/13	1.7 (1.5 to 4.6)
NSS	Complications	0/17 vs. 0/17	N/A

CI = confidence interval; N/A = not available; NNT = number needed to treat; NSS = not statistically significant; Sig. = significance; SS = statistically significant.

BEEM Critique

Risk of Bias Assessment

		Appraisers (A)
		A1	A2	A3
1	The patients were recruited consecutively.	Yes	Yes	Yes
2	The patients were adequately randomized (allocation sequence adequately generated).	Yes	Yes	Yes
3	The allocation sequence was adequately concealed.	Yes	Yes	Yes
4	The patients in all groups were similar with respect to prognostic factors.	Yes	Yes	Yes
5	All clinicians, patients, and outcome assessors were unaware of group allocation.	No	No	No
6	All groups were treated equally except for the intervention.	Yes	Yes	Yes
7	The follow-up was complete given the study duration (100% if in-hospital follow-up).	Yes	Yes	Yes
8	The patients were analyzed in the groups to which they were randomized (ITT).	Yes	Yes	Yes
9	All patient-important outcomes were considered.	No	No	No
10	The effect size of the primary outcome is clinically significant.	No	No	No

A = appraiser; ITT = intention to treat.

Funding & Conflicts of Interest

Funding

No external funding.

Conflicts of Interest

None.

Potential Threats to Validity

Chance

Type I error due to small sample size secondary to early trial termination.

Selection Bias

None identified.

Measurement Bias

No time specification for outcomes. Tools to assess intolerance to CPAP may not be ideal. The OPS assesses crying as an item, but it is not clear how this was assessed during CPAP application or if the infant was sedated. Similarly, the OPS assesses complaints of pain, but the participants are preverbal. Behavioural measures of distress may have been more appropriate

Analysis Bias

Sample size requirement was 30 per group, but the study was stopped following an interim analysis because it was believed that the primary end point was achieved in favor of helmet treatment.

Confounding