Heliox delivered by high flow nasal cannula improves oxygenation in infants with respiratory syncytial virus acute bronchiolitis

Helium-oxygen in bronchiolitis-A systematic review and meta-analysis

INTRODUCTION

Bronchiolitis is common reason for infant hospitalization. The aim of our systematic review and meta-analysis was to evaluate helium-oxygen (heliox) in bronchiolitis.

METHODS

We 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.

RESULTS

Six 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.

CONCLUSION

We 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.

Treatment of the most common respiratory infections in children

Acute respiratory infections are the most common group of infective diseases in the pediatric population. Although the improvement of health care and vaccination program has led to a significant reduction in the incidence of certain respiratory infections, the combination of a high prevalence in vulnerable pediatric categories and uncritical prescription of antibiotics, due to the inability to adequately distinguish between viruses and bacterial etiology, still represents a significant challenge for the public health system. In order to promote rational antibiotic therapy with an overall improvement of both diagnostic and therapeutic principles, acute respiratory diseases have been the subject of consideration in numerous publications and national guidelines. Nonspecific clinical manifestations with pathogen heterogeneity and both anatomical and physiological characteristics of the child's respiratory system during growth and development have created the need for individualized therapy. Since the guidelines emphasize the undoubtful and crucial benefits of symptomatic therapy (e.g. analgesics in acute otitis media, supplemental oxygen in lower respiratory tract infections with hypoxemia), the use of antibiotics and corticosteroids is indicated in selected cases with a severe clinical picture. The choice of antibiotic depends on the clinical condition, presumed causative agent, and local epidemiologic circumstances. Respiratory support (oxygen therapy and/or artificial ventilation) is reserved for inpatient treatment of cases with a particularly severe clinical picture and associated complications.

Neonatal Applications of Heliox: A Practical Review

Heliox is a mixture of helium and oxygen that may be utilized as an alternative to air-oxygen during the ventilatory support in the neonate. Special physical properties of Heliox, particularly low density, allow for improved gas flow and diffusion. First reports of Heliox use in the pediatric population were published in 1930s; however, this therapy has never gained widespread popularity despite its described beneficial effects. Historically, this was largely due to technical challenges associated with Heliox ventilation that significantly limited its use and realization of large-scale clinical trials. However, nowadays several commercially available ventilators allow easy and safe ventilation with both conventional and non-invasive modes. In the era of minimally invasive respiratory interventions in the newborn Heliox could be seen as a therapy that may potentially decrease the risk of non-invasive ventilation failure. This review presents pathophysiologic rationale for the use of Heliox in the newborn, and summarizes available data regarding applications of Heliox in the setting of neonatal intensive care unit based on clinical studies and findings from animal models. Mechanisms of action and practical aspects of Heliox delivery are thoroughly discussed. Finally, future research directions for neonatal use of Heliox are proposed.

Effects of heliox and non-invasive neurally adjusted ventilatory assist (NIV-NAVA) in preterm infants

Due to its unique properties, helium–oxygen (heliox) mixtures may provide benefits during non-invasive ventilation, however, knowledge regarding the effects of such therapy in premature infants is limited. This is the first report of heliox non-invasive neurally adjusted ventilatory assist (NIV-NAVA) ventilation applied in neonates born ≤ 32 weeks gestational age. After baseline NIV-NAVA ventilation with a standard mixture of air and oxygen, heliox was introduced for 3 h, followed by 3 h of air-oxygen. Heart rate, peripheral capillary oxygen saturation, cerebral oxygenation, electrical activity of the diaphragm (Edi) and selected ventilatory parameters (e.g., respiratory rate, peak inspiratory pressure) were continuously monitored. We found that application of heliox NIV-NAVA in preterm infants was feasible and associated with a prompt and significant decrease of Edi suggesting reduced respiratory effort, while all other parameters were stable throughout the study, and had similar values during heliox and air-oxygen ventilation. This therapy may potentially enhance the efficacy of non-invasive respiratory support in preterm neonates and reduce the number of infants progressing to ventilatory failure.

Update on current views and advances on RSV infection (Review)

Respiratory syncytial virus (RSV) infection represents an excellent paradigm of precision medicine in modern paediatrics and several clinical trials are currently performed in the prevention and management of RSV infection. A new taxonomic terminology for RSV was recently adopted, while the diagnostic and omics techniques have revealed new modalities in the early identification of RSV infections and for better understanding of the disease pathogenesis. Coordinated clinical and research efforts constitute an important step in limiting RSV global predominance, improving epidemiological surveillance, and advancing neonatal and paediatric care. This review article presents the key messages of the plenary lectures, oral presentations and posters of the '5th workshop on paediatric virology' (Sparta, Greece, 12th October 2019) organized by the Paediatric Virology Study Group, focusing on recent advances in the epidemiology, pathogenesis, diagnosis, prognosis, clinical management and prevention of RSV infection in childhood.

Impact of Helium-Oxygen Administered via High Velocity Nasal Insufflation on Delivery of Inhaled Nitric Oxide

Inhaled nitric oxide (iNO) may be continued during the transition from invasive to noninvasive respiratory support. Upper airway obstruction from laryngeal edema following extubation and lower airway obstruction from asthma and bronchiolitis may be managed with inhaled helium. The coadministration of helium with iNO and the impact on delivered amounts of iNO have not been extensively studied. A bench model simulating a spontaneously breathing infant received iNO at varying preset doses delivered with either helium-oxygen or nitrogen-oxygen via a Vapotherm unit. iNO levels were measured at the simulated trachea. Results from the two conditions were compared using t-tests. When nitrogen-oxygen was used, there was no difference between preset and measured iNO levels. A significant difference was present when helium-oxygen was used, with a 10-fold increase in measured iNO levels compared with preset values. The use of helium resulted in a significant increase in measured iNO at the level of the simulated trachea. Clinicians must be aware that iNO will not be delivered at prescribed doses when used with helium under the conditions used in this study.

High flow nasal cannula: Influence of gas type and flow rate on airway pressure and CO2 clearance in adult nasal airway replicas

BACKGROUND

High flow nasal cannula therapy is a form of respiratory support which delivers high flow rates of heated, humidified gas to the nares via specialized cannula. Two primary mechanisms of action attributed to the therapy are the provision of positive airway pressure as well as clearance of CO₂-rich exhaled gas from the upper airways.

METHODS

Physiologically accurate nose-throat airway replicas were connected at the trachea to a lung simulator, where CO₂ was supplied to mimic the CO₂ content in exhaled gas. Cannula delivered either air, oxygen or heliox (80/20%volume helium/oxygen) to the replicas at flow rates ranging from 0 to 60 l/min. Five replicas and three cannulas were compared. Tracheal pressure and CO₂ concentration were continuously measured. The lung simulator provided breaths with tidal volume of 500 ml and frequency of 18 breaths/min. Additional clearance measurements were conducted for tidal volume and breathing frequency of 750 ml and 27 breaths/min, respectively.

FINDINGS

Cannula flow rate was the dominant factor governing CO₂ concentration. Average CO₂ concentration decreased with increasing cannula flow rate, but above 30 L/min this effect was less pronounced. Tracheal positive end-expiratory pressure increased with flow rate and was lower for heliox than for air or oxygen. A predictive correlation was developed and used to predict positive end-expiratory pressure for a given cannula size as a function of supplied flow rate and occlusion of the nares.

INTERPRETATION

Compared with administration of air or oxygen, administration of heliox is expected to result in similar CO₂ clearance from the upper airway, but markedly lower airway pressure.

Respiratory support for infants with bronchiolitis, a narrative review of the literature

Bronchiolitis is a common viral disease that significantly affects infants less than 12 months of age. The purpose of this review is to present a review of the current knowledge of the uses of respiratory support in the management of infants with bronchiolitis presenting to hospital. We electronically searched MEDLINE, Cochrane, CINAHL and EMBASE (inception to 25th March 2018), to manually search for clinical trials that address the management strategies for respiratory support of infants with bronchiolitis. We identified 120 papers who met the inclusion criteria, of which 33 papers were relevant for this review with only nine randomized controlled trials. This review demonstrated that non-invasive respiratory support reduced the need for escalation of therapy, particularly the proportion of intubations required for infants with bronchiolitis. Additionally, clear economic benefits have been demonstrated when non-invasive ventilation has been used. The potential early use of non-invasive respiratory supports such as nasal high flow therapy and non-invasive ventilation may have an impact on health care costs and reduction in ICU admissions and intubation rates. High-grade evidence demonstrates safety and quality of high flow therapy in general ward settings.

Helium-oxygen mixture: clinical applicability in an intensive care unit

Objective

To evaluate if distress respiratory decreases after using helium-oxygen mixture in pediatric patients diagnosed with bronchospasm.

Methods

This is a retrospective, non-randomized study that included patients diagnosed with bronchospasm, who received a helium-oxygen mixture at three time points (30, 60, and 120 minutes) according to the organization protocol singular, and were admitted to the intensive care unit, from January 2012 to December 2013. This protocol includes patients with bronchospasm who sustained a modified Wood score of moderate to severe, even after one hour of conventional treatment.

Results

Twenty children were included in the study. The mean score of severity of the disease at the initial moment was 5.6 (SD:2.0), and at moment 120 minutes, it was 3.4 (SD: 2.0). The severity score showed a significant improvement as of 30 minutes (p<0.001).

Conclusion

The use of helium-oxygen mixture proved to be effective in diminishing the respiratory distress score for children with airway obstructions; it should be considered a supplementary therapeutic option, together with drug therapy, in specific clinical situations.

[Does heliox administered by low-flow nasal cannula improve respiratory distress in infants with respiratory syncytial virus acute bronchiolitis? A randomized controlled trial]

OBJECTIVES

The aim of our study is to evaluate whether the use of heliox (79:21) delivered through a low flow nasal cannula would improve respiratory distress in infants with acute bronchiolitis caused by respiratory syncytial virus.

METHODS

We have conducted a prospective randomized controlled study. All patients fulfilled inclusion criteria were randomized to either heliox (79:21) or air via NC at 2 L/min for a continuous 24hours. Measurements were taken at baseline, after 2hours and at the end of the 24hours.

RESULTS

We have included 104 patients into our study. The MCA-S did not show any significant difference between the two groups after 2hours 4.3 vs. 4.1 (P =.78), or at 24hours after 4.2 vs. 4.3 (P =.89). No difference was found in the proportion of participants progressed to MV, n-CPAP or oxygen via nasal cannula (RR 1.0, 0.86 and 0.89) (P= 1.0, .77 and .73). There was no notable reduction in length of treatment in Heliox group 2.42 days vs. 2.79 days in air group P =.65. The in oxygen saturation, PaO₂, and PaCO₂ did not to have any statistical difference between the two studied groups after 2hours and 24hours of treatment.

CONCLUSION

Our data showed absence of any beneficial effect of heliox in a concentration (79:21) delivered through low flow nasal cannula in terms of respiratory distress improvement in infants with RSV acute bronchiolitis.