Helium 79% / Oxygen 21%

IntroductionBronchiolitis is common reason for infant hospitalization. The aim of our systematic review and meta-analysis was to evaluate helium-oxygen (heliox) in bronchiolitis.MethodsWe screened 463 studies, assessed 22 of them, and included six randomized controlled trials. Primary outcomes were the need for continuous positive airway pressure (CPAP) or intubation, hospitalization duration, and change in the modified Woods Clinical Asthma Scale (M-WCAS). We calculated mean differences with 95% confidence intervals (CIs) for continuous outcomes and risk ratios (RRs) for dichotomous outcomes.ResultsSix studies (five double- and one single-blinded) with 560 infants were included. The risk of bias was high in one, moderate in four, and low in one. The RR for the need for CPAP (three studies) was 0.87 (CI: 0.56-1.35), and for intubation (four studies) was 1.39 (CI: 0.53-3.63), heliox compared to air-oxygen. The hospital stay (four studies) was 0.25 days longer (CI: -0.22 to 0.71) in the heliox group. The mean decrease in M-WCAS from the baseline (three studies) was 1.90 points (CI: 1.46-2.34) greater in the heliox group.ConclusionWe found low-quality evidence that heliox does not reduce the need for CPAP, intubation, or length of hospitalization for bronchiolitis. Based on the M-WCAS scores, heliox seems to relieve respiratory distress symptoms rapidly after its initiation. The included studies had high heterogeneity in their methods and included relatively mild cases of bronchiolitis. A larger randomized controlled trial with more severe cases of bronchiolitis with enough power to analyze the need for intubation is needed in the future.

Abstract licence: CC BY-NC

When used as a driving gas during NIV in hypercapnic COPD exacerbation, a helium-oxygen (He/O2) mixture reduces the work of breathing and gas trapping. The potential for He/O2 to reduce the rate of NIV failure leading to intubation and invasive mechanical ventilation has been evaluated in several RCTs. The goal of this meta-analysis is to assess the effect of NIV driven by He/O2 compared to air/O2 on patient-centered outcomes in hypercapnic COPD exacerbation. Relevant RCTs were searched using standard procedures. The main endpoint was the rate of NIV failure. The effect size was computed by a fixed-effect model, and estimated as odds ratio (OR) with 95% confidence interval (CI). Additional endpoints were ICU mortality, NIV-related side effects, and the length and costs of ICU stay. Three RCTs fulfilled the selection criteria and enrolled a total of 772 patients (386 patients received He/O2 and 386 received air/O2). Pooled analysis showed no difference in the rate of NIV failure when using He/O2 mixture compared to air/O2: 17 vs 19.7%, respectively; OR 0.84, 95% CI 0.58-1.22; p = 0.36; I 2 for heterogeneity = 0%, and no publication bias. ICU mortality was also not different: OR 0.8, 95% CI 0.45-1.4; p = 0.43; I 2 = 5%. However, He/O2 was associated with less NIV-related adverse events (OR 0.56, 95% CI 0.4-0.8, p = 0.001), and a shorter length of ICU stay (difference in means = -1.07 day, 95% CI -2.14 to -0.004, p = 0.049). Total hospital costs entailed by hospital stay and NIV gas were not different: difference in means = -279$, 95% CI -2052-1493, p = 0.76. Compared to air/O2, He/O2 does not reduce the rate of NIV failure in hypercapnic COPD exacerbation. It is, however, associated with a lower incidence of NIV-related adverse events and a shortening of ICU length of stay with no increase in hospital costs.

Abstract licence: CC BY