Nasal continuous positive airway pressure with heliox in infants with acute bronchiolitis

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.

[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.

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

OBJECTIVE

The objective of this study is to evaluate the hypothesis that use of heliox would result in improvement of gas exchange when used with high flow nasal cannula in infants with RSV acute bronchiolitis.

METHODS

All patients that met the inclusion criteria were randomized to either heliox (70:30) or air-oxygen mixture 30% via high flow nasal cannula at 8L/min for a continuous 24h. Measurements were taken at baseline, after 2h, and at the end of the 24h.

RESULTS

This prospective study included 48 patients. After 2h of treatment with heliox, the oxygen saturation and PaO₂ significantly improved when compared with the air-oxygen group, 98.3% vs. 92.9%, 62.0mmHg vs. 43.6mmHg (p=0.04 and 0.01), respectively. Furthermore, PaO₂/FiO₂ ratio was significantly higher in the heliox group when compared with the air-oxygen group, 206.7 vs. 145.3. Nevertheless, CO₂ showed better elimination when heliox was used, without significance. MWCA score dropped significantly in the heliox group, 2.2 points vs. 4.0 points in air-oxygen (p=0.04), 2h after starting the therapy.

CONCLUSION

Transient improvement of oxygenation in infants with RSV acute bronchiolitis during the initial phase of the therapy is associated with heliox when provided with HFNC, may provide a precious time for other therapeutic agents to work or for the disease to resolve naturally, avoiding other aggressive interventions.

CPAP and High-Flow Nasal Cannula Oxygen in Bronchiolitis

Severe respiratory failure develops in some infants with bronchiolitis because of a complex pathophysiologic process involving increased airways resistance, alveolar atelectasis, muscle fatigue, and hypoxemia due to mismatch between ventilation and perfusion. Nasal CPAP and high-flow nasal cannula (HFNC) oxygen may improve the work of breathing and oxygenation. Although the mechanisms behind these noninvasive modalities of respiratory support are not well understood, they may help infants by way of distending pressure and delivery of high concentrations of warmed and humidified oxygen. Observational studies of varying quality have suggested that CPAP and HFNC may confer direct physiologic benefits to infants with bronchiolitis and that their use has reduced the need for intubation. No trials to our knowledge, however, have compared CPAP with HFNC in bronchiolitis. Two randomized trials compared CPAP with oxygen delivered by low-flow nasal cannula or face mask and found some improvements in blood gas results and some physiologic parameters, but these trials were unable to demonstrate a reduction in the need for intubation. Two trials evaluated HFNC in bronchiolitis (one comparing it with headbox oxygen, the other with nebulized hypertonic saline), with the results not seeming to suggest important clinical or physiologic benefits. In this article, we review the pathophysiology of respiratory failure in bronchiolitis, discuss these trials in detail, and consider how future research studies may be designed to best evaluate CPAP and HFNC in bronchiolitis.

Heliox inhalation therapy for bronchiolitis in infants

BACKGROUND

Bronchiolitis is the leading cause of hospitalisation among infants in high-income countries. Acute viral bronchiolitis is associated with airway obstruction and turbulent gas flow. Heliox, a mixture of oxygen and the inert gas helium, may improve gas flow through high-resistance airways and decrease the work of breathing. In this review, we selected trials that objectively assessed the effect of the addition of heliox to standard medical care for acute bronchiolitis.

OBJECTIVES

To assess heliox inhalation therapy in addition to standard medical care for acute bronchiolitis in infants with respiratory distress, as measured by clinical endpoints (in particular the rate of endotracheal intubation, the rate of emergency department discharge, the length of treatment for respiratory distress) and pulmonary function testing (mainly clinical respiratory scores).

SEARCH METHODS

We searched CENTRAL (2015, Issue 2), MEDLINE (1966 to March week 3, 2015), EMBASE (1974 to March 2015), LILACS (1982 to March 2015) and the National Institutes of Health (NIH) website (May 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of heliox in infants with acute bronchiolitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality.

MAIN RESULTS

We included seven trials involving 447 infants younger than two years with respiratory distress secondary to viral bronchiolitis. All children were recruited from a paediatric intensive care unit (PICU; 378 infants), except in one trial (emergency department; 69 infants). All children were younger than two (under nine months in two trials and under three months in one trial). Positive tests for respiratory syncytial virus (RSV) were required for inclusion in five trials. The two other trials were carried out in the bronchiolitis seasons. Seven different protocols were used for inhalation therapy with heliox.When heliox was used in the PICU, we observed no significant reduction in the rate of intubation: risk ratio (RR) 2.73 (95% confidence interval (CI) 0.96 to 7.75, four trials, 408 infants, low quality evidence). When heliox inhalation was used in the emergency department, we observed no increase in the rate of discharge: RR 0.51 (95% CI 0.17 to 1.55, one trial, 69 infants, moderate quality evidence).There was no decrease in the length of treatment for respiratory distress: mean difference (MD) -0.19 days (95% CI -0.56 to 0.19, two trials, 320 infants, moderate quality evidence). However, in the subgroup of infants who were started on nasal continuous positive airway pressure (nCPAP) right from the start, because of severe respiratory distress, heliox therapy reduced the length of treatment: MD -0.76 days (95% CI -1.45 to -0.08, one trial, 21 infants, low quality evidence). No adverse events related to heliox inhalation were reported.We found that infants treated with heliox inhalation had a significantly lower mean clinical respiratory score in the first hour after starting treatment when compared to those treated with air or oxygen inhalation: MD -1.04 (95% CI -1.60 to -0.48, four trials, 138 infants, moderate quality evidence). This outcome had statistical heterogeneity, which remained even after removing the study using a standard high-concentration reservoir mask. Several factors may explain this heterogeneity, including first the limited number of patients in each trial, and the wide differences in the baseline severity of disease between studies, with the modified Wood Clinical Asthma Score (m-WCAS) in infants treated with heliox ranging from less than two to more than seven.

AUTHORS' CONCLUSIONS

Current evidence suggests that the addition of heliox therapy may significantly reduce a clinical score evaluating respiratory distress in the first hour after starting treatment in infants with acute RSV bronchiolitis. We noticed this beneficial effect regardless of which heliox inhalation protocol was used. Nevertheless, there was no reduction in the rate of intubation, in the rate of emergency department discharge, or in the length of treatment for respiratory distress. Heliox could reduce the length of treatment in infants requiring CPAP for severe respiratory distress. Further studies with homogeneous logistics in their heliox application are needed. Inclusion criteria must include a clinical severity score that reflects severe respiratory distress to avoid inclusion of children with mild bronchiolitis who may not benefit from heliox inhalation. Such studies would provide the necessary information as to the appropriate place for heliox in the therapeutic schedule for severe bronchiolitis.

Evolution of Noninvasive Mechanical Ventilation Use: A Cohort Study Among Italian PICUs

OBJECTIVE

To assess how clinical practice of noninvasive ventilation has evolved in the Italian PICUs.

DESIGN

National, multicentre, retrospective, observational cohort.

SETTING

Thirteen Italian medical/surgical PICUs that participated in the Italian PICU Network.

PATIENTS

Seven thousand one-hundred eleven admissions of children with 0-16 years old admitted from January 1, 2011, to December 31, 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cause of respiratory failure, length and mode of noninvasive ventilation, type of interfaces, incidence of treatment failure, and outcome were recorded. Data were compared with an historical cohort of children enrolled along 6 months from November 1, 2006, to April 30, 2007, over the viral respiratory season. Seven thousand one-hundred eleven PICU admissions were analyzed, and an overall noninvasive ventilation use of 8.8% (n = 630) was observed. Among children who were admitted in the PICU without mechanical ventilation (n = 3,819), noninvasive ventilation was used in 585 patients (15.3%) with a significant increment among the three study years (from 11.6% in 2006 to 18.2% in 2012). In the endotracheally intubated group, 17.2% children received noninvasive ventilation at the end of the weaning process to avoid reintubation: 11.9% in 2006, 15.3% in 2011, and 21.6% in 2012. Noninvasive ventilation failure rate raised from 10% in 2006 to 16.1% in 2012.

CONCLUSIONS

Noninvasive ventilation is increasingly and successfully used as first respiratory approach in several, but not all, Italian PICUs. The current study shows that noninvasive ventilation represents a feasible and safe technique of ventilatory assistance for the treatment of mild acute respiratory failure. Noninvasive ventilation was used as primary mode of ventilation in children with low respiratory tract infection (mainly in bronchiolitis and pneumonia), in acute on chronic respiratory failure or to prevent reintubation.

The potential of heliox as a therapy for acute respiratory distress syndrome in adults and children: a descriptive review

BACKGROUND

In neonatal respiratory distress syndrome (RDS) and acute RDS (ARDS) mechanical ventilation is often necessary to manage hypoxia, whilst protecting the lungs through lower volume ventilation and permissive hypercapnia. Mechanical ventilation can, however, induce or aggravate the lung injury caused by the respiratory distress. Helium, in a gas mixture with oxygen (heliox), has a low density and can reduce the flow in narrow airways and allow for lower driving pressures.

OBJECTIVES

The aim of this study was to review preclinical and clinical studies of the use of heliox ventilation in acute lung injury associated with respiratory failure.

METHODS

A systematic search was executed in the PubMed and EMBASE databases, with search terms referring to ARDS or an acute lung injury condition associated with respiratory failure and the corresponding intervention.

RESULTS

A total of 576 papers were retrieved. After the majority had been excluded 20 papers remained, of which 6 articles described animal models (3 paediatric; 3 adult animal models) and 14 were clinical studies, of which 12 described paediatric patient populations and 2 adult patient populations. In both paediatric and adult animal models, heliox improved gas exchange while allowing for less invasive ventilation in a wide variety of models using different ventilation modes. Clinical studies show a reduction in the work of breathing during heliox ventilation, with a concomitant increase in pH and decrease in PaCO2 levels compared to oxygen ventilation.

CONCLUSIONS

Although evidence so far is limited, there may be a rationale for heliox ventilation in ARDS as an intervention to improve ventilation and reduce the work of breathing.

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.

Heliox therapy in bronchiolitis: phase III multicenter double-blind randomized controlled trial

BACKGROUND AND OBJECTIVE

Supportive care remains the mainstay of therapy in bronchiolitis. Earlier studies suggest that helium-oxygen therapy may be beneficial, but evidence is limited. We aimed to compare efficacy of 2 treatment gases, Heliox and Airox (21% oxygen + 79% helium or nitrogen, respectively), on length of hospital treatment for bronchiolitis.

METHODS

This was a multicenter randomized blinded controlled trial of 319 bronchiolitic infant subjects randomly assigned to either gas; 281 subjects completed the study (140 Heliox, 141 Airox), whose data was analyzed. Treatment was delivered via facemask (nasal cannula, if the facemask intolerant) ± continuous positive airway pressure (CPAP). Severe bronchiolitics received CPAP from the start. Primary end point was length of treatment (LoT) required to alleviate hypoxia and respiratory distress. Secondary end-points were proportion of subjects needing CPAP; CPAP (LoT); and change in respiratory distress score.

RESULTS

Analysis by intention to treat (all subjects); median LoT (inter-quartile range, days): Heliox 1.90 (1.08-3.17), Airox 1.87 (1.11-3.34), P = .41. Facemask tolerant subgroup: Heliox 1.46 (0.85-1.95), Airox 2.01 (0.93-2.86), P = .03. Nasal cannula subgroup: Heliox 2.51 (1.21-4.32), Airox 2.81 (1.45-4.78), P = .53. Subgroup started on CPAP: Heliox 1.55 (1.38-2.01), Airox 2.26 (1.84-2.73), P = .02. Proportion of subjects needing CPAP: Heliox 17%, Airox 19%, O.R. 0.87 (0.47-1.60), P = .76. Heliox reduced respiratory distress score after 8 hours (mixed models estimate, -0.1298; P < .001). The effect was greater for facemask compared with nasal cannula (mixed models estimate, 0.093; P = .04).

CONCLUSIONS

Heliox therapy does not reduce LoT unless given via a tight-fitting facemask or CPAP. Nasal cannula heliox therapy is ineffective.

Heliox non-invasive ventilation for preventing extubation failure in preterm infants

OBJECTIVES

Our aim was to assess whether non-invasive ventilation with heliox may decrease the incidence of extubation failure in preterm infants with RDS.

METHODS

Infants <29 weeks of gestation were treated immediately after extubation with heliox combined with nasal continuous airway pressure (Hx-NCPAP) or bilevel NCPAP (Hx-BiPAP) for 24 h, while infants in the control groups were treated with conventional NCPAP or BiPAP. The primary endpoint was the comparison of the extubation failure rate in the two groups, where failure was defined as the need for MV during the 24 h following extubation.

RESULTS

Eighteen infants were assigned to the heliox group and 18 to the control group. The extubation failure rate was similar (p = 0.249) in the heliox (n = 6; 33%) and in the control group (n = 9; 50%), but required mean airway pressure (MAP: 4.0+1.0 vs. 4.8+1.2 cm H2O; p = 0.037) and PaCO2 (39+8 mmHg vs. 52+7 mmHg; p < 0.001) at 24 h of treatment were lower in the heliox group.

CONCLUSIONS

Non-invasive ventilation with heliox was not effective in decreasing extubation failure in preterm infants with RDS, but did improve their respiratory function. Our findings might support the planning of large randomized controlled studies to evaluate the effectiveness of heliox non-invasive ventilation for decreasing extubation failure in premature infants.

Non-invasive ventilation for severe bronchiolitis: analysis and evidence

OBJECTIVES

(1) To examine whether infants with severe bronchiolitis, fulfilling criteria for further respiratory support, could be managed outside a Pediatric Intensive Care Unit (PICU) with non-invasive ventilation (NIV) alone. (2) To study the characteristics, clinical course and outcome of NIV responders and non responders to assess safety and efficacy and inform guideline construction.

HYPOTHESIS

Infants with severe bronchiolitis can be safely managed with NIV outside a PICU.

STUDY DESIGN

Retrospective case review.

PATIENT SELECTION

Cohort of infants with objective evidence of severe bronchiolitis requiring respiratory support nursed in a Pediatric High Dependency Unit (PHDU) and/or Intensive Care Unit (ICU) between 2001 and 2007.

METHODOLOGY

Analysis of patient characteristics and respiratory parameters at admission and initiation of ventilation, changes after 2 and 4 hr of NIV or invasive ventilation, complications, short and long-term outcomes were analyzed.

RESULTS

One thousand and thirty-five infants with bronchiolitis were admitted with 67 ventilation episodes identified from 65 patients. Fifty-five episodes, including 34 with apnea, were treated exclusively with NIV. Six infants failed to respond and were invasively ventilated. Six patients were invasively ventilated at presentation. Non-responders had a significantly higher rate of bacterial infection. Significant improvements in respiratory parameters in responders occurred by 2 hr and sustained at 4 hr. Duration of hospital stay, ventilation requirement and oxygen requirement were significantly shorter in responders. Short and longer-term follow up data did not identify any adverse effects related to NIV.

CONCLUSIONS

NIV was effective in 80% of infants receiving respiratory support for severe bronchiolitis.

Nasal continuous positive airway pressure with heliox in preterm infants with respiratory distress syndrome

OBJECTIVE

To assess the therapeutic effects of breathing a low-density helium and oxygen mixture (heliox, 80% helium and 20% oxygen) in premature infants with respiratory distress syndrome (RDS) treated with nasal continuous positive airway pressure (NCPAP).

METHODS

Infants born between 28 and 32 weeks of gestational age with radiologic findings and clinical symptoms of RDS and requiring respiratory support with NCPAP within the first hour of life were included. These infants were randomly assigned to receive either standard medical air (control group) or a 4:1 helium and oxygen mixture (heliox group) during the first 12 hours of enrollment, followed by medical air until NCPAP was no longer needed.

RESULTS

From February 2008 to September 2010, 51 newborn infants were randomly assigned to two groups, 24 in the control group and 27 in the heliox group. NCPAP with heliox significantly decreased the risk of mechanical ventilation in comparison with NCPAP with medical air (14.8% vs 45.8%).

CONCLUSIONS

Heliox increases the effectiveness of NCPAP in the treatment of RDS in premature infants.

Noninvasive ventilation with helium-oxygen in children

Most existing literature on noninvasive ventilation (NIV) in combination with helium-oxygen (HELIOX) mixtures focuses on its use in adults, basically for treatment of acute exacerbations of chronic obstructive pulmonary disease. This article reviews and summarizes the theoretical basis, existing clinical evidence, and practical aspects of the use of NIV with HELIOX in children. There is only a small body of literature on HELIOX in pediatric NIV but with positive results. The reported experience focuses on treatment for patients with severe acute bronchiolitis who cannot be treated with standard therapies. The inert nature of helium adds no biological risk to NIV performance. Noninvasive ventilation with HELIOX is a promising therapeutic option for children with various respiratory pathologies who do not respond to conventional treatment. Further controlled studies should be warranted.

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

INTRODUCTION

Continuous positive airway pressure (CPAP), used either alone or associated with heliox (CPAP-He), has become a popular therapeutic option for bronchiolitis. This systematic review assesses the impact of CPAP on endotracheal intubation, carbon dioxide pressure (PCO(2) ) and respiratory distress in patients with bronchiolitis.

METHODS

Systematic search including studies that used CPAP or CPAP-He in infants with bronchiolitis admitted to a PICU. Data analysis included descriptive statistics and the GRADE system.

RESULTS

Five CPAP (one crossover randomized controlled trial [RCT] and four before-after studies) and three CPAP-He (one quasi-RCT and two before-after) studies were included. CPAP was reported to reduce PCO(2) (-6.9 to -11.7 mmHg, respectively, P < 0.015), respiratory rate (-12 to -16 breaths/min after 2 hr, P < 0.01) and the modified Wood clinical asthma score (mWCAS, -2.2 points after 1 hr, P < 0.01). CPAP-He studies observed decreases in PCO(2) (-9.7 mmHg, P < 0.05), mWCAS (-2.12 points, P < 0.001), and respiratory rate (-8 to -13.7 breaths/min, P < 0.05) after 1 hr of treatment. Endotracheal intubation rates ranged from 0-12.5% (CPAP-He) to 17-27% (CPAP). After applying the GRADE system, the quality of evidence for a beneficial effect of CPAP and CPAP-He was classified as low.

CONCLUSIONS

The evidence supporting the use of CPAP to reduce PCO(2) and respiratory distress in bronchiolitis is of low methodological quality, and there is no conclusive evidence that CPAP reduces the need for intubation. No definitive conclusions could be drawn about the CPAP-He effect. Further research using higher quality methodology is needed to clarify the beneficial role of these interventions.

Helmet-delivered heliox-CPAP in severe upper airway obstruction caused by PHACES syndrome

We present the case of a 4-month-old girl with PHACES syndrome and severe upper respiratory airway obstruction secondary to multiple subglottic and tracheal hemangiomas effectively treated with heliox-CPAP delivered by helmet (HH-CPAP).

Update on management of bronchiolitis

PURPOSE OF REVIEW

Bronchiolitis impacts millions of infants worldwide. Although several therapeutic options stem from highly plausible theoretical rationales for success and some may even offer modest short-term symptom relief, none has been conclusively shown to alter the course of the disease or its major outcomes. However, several recent papers shed light on which treatments show promising preliminary evidence and offer insight into future research endeavors on this topic. This review will summarize bronchiolitis therapy in view of this recent evidence.

RECENT FINDINGS

The agents in which theory promises but treatment does not deliver include systemic corticosteroids alone, inhaled bronchodilators alone and antileukotrienes. The most promising combination to date appears to be that of oral dexamethasone and inhaled epinephrine but numerous related issues need to be clarified further. Caretakers need to be counselled about the usual protracted clinical course of bronchiolitis.

SUMMARY

Because bronchiolitis is a highly heterogeneous entity, future research challenges should include detailed characterization of infants most likely to benefit from given interventions. In the meantime, stick with the good old time-honored supportive route!

Pathology of small airways disease

CONTEXT

The term small airways disease encompasses a generally poorly understood group of lung diseases that may arise primarily within the small airways or secondarily from diseases primarily affecting the bronchi or lung parenchyma. Their histology may be confusing; however, because treatments and prognoses vary, correct pathologic diagnosis is important.

OBJECTIVE

To present a nonexhaustive review of the pathology of primary and secondary small airways diseases, including small airways disease related to tobacco; to various other exposures, including mineral dusts; to diseases involving other areas of the lung with secondary bronchiolar involvement; and to recently described bronchiolitic disorders.

DATA SOURCES

Current literature is reviewed.

CONCLUSIONS

Small airways diseases include a wide variety of diseases of which the pathologist must consider. Uncommon conditions such as diffuse idiopathic neuroendocrine cell hyperplasia and diffuse panbronchiolitis may show relatively specific diagnostic features histologically; however, most small airways diseases exhibit nonspecific histologic features. Conditions not considered primary pulmonary diseases, such as collagen vascular diseases, bone marrow transplantation, and inflammatory bowel disease, must also be considered in patients with small airways changes histologically. Clinical and radiologic correlation is important for obtaining the best possible diagnosis.

Heliox inhalation therapy for bronchiolitis in infants

BACKGROUND

Acute viral bronchiolitis is associated with airway obstruction and turbulent gas flow. Heliox, a mixture of oxygen and the inert gas helium, may improve gas flow through high-resistance airways and decrease the work of breathing.

OBJECTIVES

To assess heliox in addition to standard medical care for acute bronchiolitis in infants.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2), which includes the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register, MEDLINE (1966 to June 2009), EMBASE (June 2009), LILACS (May 2009) and the NIH web site (May 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of heliox in infants with acute bronchiolitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality. We pooled data from individual trials.

MAIN RESULTS

We included four trials involving 84 infants under two years of age with respiratory distress secondary to bronchiolitis caused by respiratory syncytial virus (RSV) and requiring paediatric intensive care unit (PICU) hospitalisation. We found that infants treated with heliox inhalation had a significantly lower mean clinical respiratory score in the first hour after starting treatment when compared to those treated with air or oxygen inhalation (mean difference (MD) -1.15, 95% confidence interval (CI) -1.98 to -0.33, P = 0.006, n = 69). There was no clinically significant reduction in the rate of intubation (risk ratio (RR) 1.38, 95% CI 0.41 to 4.56, P = 0.60, n = 58), in the need for mechanical ventilation (RR 1.11, 95% CI 0.36 to 3.38, P = 0.86, n = 58), or in the length of stay in a PICU (MD = -0.15 days, 95% CI -0.92 to 0.61, P = 0.69, n = 58). No adverse events related to heliox inhalation were reported.

AUTHORS' CONCLUSIONS

Current evidence suggests that the addition of heliox therapy may significantly reduce a clinical score evaluating respiratory distress in the first hour after starting treatment in infants with acute RSV bronchiolitis. Nevertheless, there was no reduction in the rate of intubation, in the need for mechanical ventilation, or in the length of PICU stay. Further studies with homogeneous logistics in their heliox application are needed. Such studies would provide necessary information as to the appropriate place for heliox in the therapeutic schedule for severe bronchiolitis.

Current therapies in bronchiolitis

Viral bronchiolitis is the most common cause of hospitalization among infants. Despite its prevalence, no consistently effective therapy has been found to date, providing the driving force behind much of the ongoing research into this illness. In this review, we present a summary of the most recent published trials of interventions for bronchiolitis. Included are studies evaluating bronchodilators, corticosteroids, positive pressure ventilation, as well as 3 newer therapies for bronchiolitis: heliox, mucolytics, and leukotriene receptor antagonists.

Helmet-delivered continuous positive airway pressure with heliox in respiratory syncytial virus bronchiolitis

AIM

The objective of this study was to check the feasibility and efficacy of helmet-delivered heliox-continuous positive airway pressure (CPAP) in infants with bronchiolitis.

METHODS

Children <3 months of age diagnosed with respiratory syncytial virus bronchiolitis and recurrent apnoeas or a venous PCO(2) >55 mmHg or a transcutaneous oxygen saturation <92% in room air were eligible for inclusion in the study. CPAP was delivered by a noninvasive ventilator connected to a heliox port. The interface was a helmet.

RESULTS

Eight consecutive infants fulfilled the inclusion criteria. Apnoeas were present in six children before respiratory support was started; they disappeared in five of them. Two infants had to be changed to pressure support noninvasive ventilation, and one of them required intubation. No side effects were recorded.

CONCLUSION

We propose a relatively new device to deliver heliox-CPAP in small infants with bronchiolitis. Although this is just a descriptive study with a short sample, this system seems to be feasible and effective.

Bronchiolitis: recent evidence on diagnosis and management

Viral bronchiolitis is a leading cause of acute illness and hospitalization of young children. Research into the variation in treatment and outcomes for bronchiolitis across different settings has led to evidence-based clinical practice guidelines. Ongoing investigation continues to expand this body of evidence. Authors of recent surveillance studies have defined the presence of coinfections with multiple viruses in some cases of bronchiolitis. Underlying comorbidities and young age remain the most important predictors for severe bronchiolitis. Pulse oximetry plays an important role in driving use of health care resources. Evidence-based reviews have suggested a limited role for diagnostic laboratory or radiographic tests in typical cases of bronchiolitis. Several large, recent trials have revealed a lack of efficacy for routine use of either bronchodilators or corticosteroids for treatment of bronchiolitis. Preliminary evidence suggests a potential future role for a combination of these therapies and other novel treatments such as nebulized hypertonic saline.

The Effects of helium/oxygen mixture (heliox) before and after extubation in long-term mechanically ventilated very low birth weight infants

OBJECTIVES

Our goal was to evaluate the effects of a helium/oxygen mixture (heliox) on pulmonary mechanics and gas exchange in preterm infants during both conventional and noninvasive ventilation.

PATIENTS AND METHODS

Ten preterm infants, ventilated from birth, were enrolled. Resistive work of breathing, pulmonary compliance, static compliance, respiratory rate, minute ventilation, ventilatory support, and gas exchange were measured before and during treatment. One hour after heliox therapy, subjects who showed a decrease of peak inspiratory pressure of >20% of the initial value were extubated and shifted to nasal bilevel positive airway pressure with heliox for the following 3 hours. Pulmonary mechanics and ventilatory parameters were measured during air/oxygen ventilation and again 10 minutes and 1 hour after starting heliox. Transcutaneous pressure of O(2) and CO(2), oxygen saturation, and respiratory rate were recorded continuously. Arterial blood gases were measured immediately before and 1 hour after initiating bilevel positive airway pressure. To maintain oxygen saturation at >92% during the bilevel positive airway pressure phase, the mean fraction of inspired oxygen was increased from 0.34 to 0.36.

RESULTS

Mean peak inspiratory pressure decreased from 21.4 to 17.4 cmH(2)O, work of breathing decreased from 0.46 to 0.22 joule/L, and transcutaneous pressure of CO(2) decreased from 52.3 to 49.1 mmHg. Mean transcutaneous pressure of O(2) improved from 42.8 to 46.7 mmHg, and minute ventilation improved from 332 to 478 mL/kg per minute. No significant differences were observed in mean airway pressure, respiratory rate, oxygen saturation, pulmonary compliance, and static compliance. Eight infants were extubated. One of them needed to be reintubated after 5 hours.

CONCLUSIONS

Our data show that mechanical ventilation with heliox reduces resistive work of breathing and ventilatory support requirements and improves gas exchange in preterm infants.

High frequency oscillatory ventilation for respiratory failure due to RSV bronchiolitis

OBJECTIVE

To describe the time course of high frequency oscillatory ventilation (HFOV) in respiratory syncytial virus (RSV) bronchiolitis.

DESIGN

Retrospective charts review.

SETTING

A tertiary paediatric intensive care unit.

PATIENTS AND PARTICIPANTS

Infants with respiratory failure due to RSV infection.

INTERVENTION

HFOV.

MEASUREMENTS AND RESULTS

Pattern of lung disease, ventilatory settings, blood gases, infant's vital parameters, sedation and analgesia during the periods of conventional mechanical ventilation (CMV, 6 infants), after initiation of HFOV (HFOVi, 9 infants), in the middle of its course (HFOVm), at the end (HFOVe) and after extubation (Post-Extub) were compared. All infants showed a predominant overexpanded lung pattern. Mean airway pressure was raised from a mean (SD) 12.5 (2.0) during CMV to 18.9 (2.7) cmH(2)O during HFOVi (P < 0.05), then decreased to 11.1(1.3) at HFOVe (P < 0.05). Mean FiO(2) was reduced from 0.68 (0.18) (CMV) to 0.59 (0.14) (HFOVi) then to 0.29 (0.06) (P < 0.05) at HFOVe and mean peak to peak pressure from 44.9 (12.4) cmH(2)O (HFOVi) to 21.1 (7.7) P < 0.05 (HFOVe) while mean (SD) PaCO(2) showed a trend to decrease from 72 (22) (CMV) to 47 (8) mmHg (HFVOe) and mean infants respiratory rate a trend to increase from 20 (11) (HFOVi) to 34 (14) (HFOVe) breaths/min. With usual doses of sedatives and opiates, no infant was paralysed and all were extubated to CPAP or supplemental oxygen after a mean of 120 h.

CONCLUSION

RSV induced respiratory failure with hypercapnia can be managed with HFOV using high mean airway pressure and large pressure swings while preserving spontaneous breathing.

Nasal continuous positive airway pressure with heliox versus air oxygen in infants with acute bronchiolitis: a crossover study

OBJECTIVE

The purpose of this work was to evaluate the effects of administering either heliox or air oxygen in combination with nasal continuous positive airway pressure in infants with refractory bronchiolitis.

PATIENT AND METHODS

We conducted a prospective, interventional, single-center, crossover study in a teaching hospital including infants 1 month to 2 years of age, consecutively admitted to the PICU from February 2004 to February 2005 for treatment of severe acute bronchiolitis unresponsive to therapy. Patients with a clinical score (Modified Wood's Clinical Asthma Score) of >5, arterial oxygen saturation of <92%, or transcutaneous CO(2) pressure of >50 mmHg despite supportive therapy, nebulized L-epinephrine, and heliox therapy through a nonrebreathing reservoir face mask were eligible. During the study period, 40 infants with bronchiolitis were admitted to the PICU; 12 fulfilled inclusion criteria. A predetermined balanced sequential allocation to either 30 minutes of treatment with nasal continuous positive airway pressure with heliox or to air-oxygen nasal continuous positive airway pressure was performed. Measurements were taken at baseline and after 30 minutes of each treatment.

RESULTS

Baseline mean values were as follows: nasal continuous positive airway pressure of 7.2 cmH(2)O; clinical score of 7.7 points; transcutaneous CO(2) pressure of 61.6 mmHg; and arterial oxygen saturation of 88.6%, with the fraction of inspired oxygen at 35.4%. Clinical score, transcutaneous CO(2) pressure, and arterial oxygen saturation improved during the study time with both heliox-nasal continuous positive airway pressure and air-oxygen-nasal continuous positive airway pressure: after 1 hour, the clinical score fell 1.7 points, transcutaneous CO(2) pressure decreased 8.2 mmHg, and arterial oxygen saturation increased by 7.7%. Improvement in clinical score was double with heliox-nasal continuous positive airway pressure compared with the air-oxygen-nasal continuous positive airway pressure (2.12 vs 1.08 points), and the fall in the transcutaneous CO(2) pressure was greater with heliox-nasal continuous positive airway pressure compared with air-oxygen-nasal continuous positive airway pressure (9.7 vs 5.4 mm Hg). There was no difference in arterial oxygen saturation between groups. No patients required endotracheal intubation. No adverse effects attributable to either of the study interventions were detected.

CONCLUSIONS

Nasal continuous positive airway pressure improves the clinical score and the CO(2) elimination of infants with refractory bronchiolitis. These positive effects are significantly enhanced when nasal continuous positive airway pressure is combined with heliox instead of air oxygen. Both techniques are noninvasive, seem safe, and may reduce the need for endotracheal intubation.

Utilidad del Heliox en el manejo de una obstrucción grave de la vía aérea por un hemangioma subglótico

Heliox therapy, alone or combined with noninvasive ventilation, has successfully been used in the treatment of infants and children with respiratory disease such as airway obstruction. We describe the case of a 1-month-old infant with severe upper respiratory airway obstruction (approximately 80 %) secondary to multiple cervical hemangiomatosis effectively treated with either Heliox alone or combined with nasal continuous positive airway pressure. This treatment provided symptomatic relief and facilitated diagnosis and subsequent application of specific treatment; the patient was free of signs of respiratory distress and the use of aggressive treatments such as endotracheal intubation or tracheal cannulation was avoided. Heliox can constitute a multipurpose, safe and useful tool in the noninvasive management of infants and children with serious obstructive respiratory disease.

Eficacia del tratamiento con heliox en niños con insuficiencia respiratoria

OBJECTIVE

To analyze response to heliox therapy in critically ill infants and children with upper and/or lower airway respiratory insufficiency.

PATIENTS AND METHODS

Sixty-five patients, aged between 12 days and 8 years old, treated with heliox through facial mask, nasal prongs or non-invasive ventilation were studied. Diagnoses were bronchiolitis (25), upper postextubation respiratory insufficiency (19), respiratory insufficiency after airway surgery (14), and croup-laryngotracheomalacia (7). Response to heliox treatment was measured by the change in clinical scores, respiratory rate, heart rate, pulse oximetry, blood gas analysis, and the need for non-invasive and invasive mechanical ventilation.

RESULTS

Fifty-four patients (83.1 %) improved after heliox therapy, with statistically significant differences in clinical score (from 8.7 to 5.5), respiratory rate (from 51.4 to 38.8 rpm), and heart rate (from 161.6 to 145.6 bpm). No changes were observed in saturation or blood gas analysis. After heliox therapy, 29.8 % of patients required non-invasive ventilation and 26.5 % required intubation. Patients with bronchiolitis and those aged less than 1 year had a lesser response to heliox therapy and more frequently required non-invasive ventilation. No significant differences were found in intubation requirements. No adverse effects were observed.

CONCLUSIONS

Heliox therapy improved clinical scores in infants and children with upper and lower airway respiratory insufficiency, but a significant percentage of patients needed non-invasive or invasive mechanical ventilation.

Central nervous system infection is an important cause of death in underfives hospitalised with World Health Organization (WHO) defined severe and very severe pneumonia

Over 6 years, 1667 children aged 2-59 months admitted for pneumonia [1287 severe and 380 very severe] were studied. The case fatality rate (CFR) in children with severe pneumonia was 2.1% and 14.3% with CNS infection, with very severe pneumonia the CFR was 18.9%, 10.4% in those with hypoxemia and 43.6% with CNS infection. High CFRs were associated with CNS infection and inability to drink/cyanosis. The appropriate management of children with very severe pneumonia should include cerebrospinal fluid examination, oxygen monitoring and possibly ventilated support, suggesting that these are minimal standards of care at the district hospital.