Noninvasive high-frequency oscillatory ventilation versus nasal continuous positive airway pressure in preterm infants with moderate-severe respiratory distress syndrome: A preliminary report

Update on nasal high frequency oscillatory ventilation: A living review

Non-invasive high-frequency oscillatory ventilation (NHFOV) is the main non-conventional ventilatory mode used in newborn infants. NHFOV has been spreading, while knowledge about its physiology, mechanics and clinical application has increased overtime. This is to be considered as a living review, since we here update the knowledge that was originally summarized in a previously published review. We first focus on physiology of such a complex respiratory support technique with practical data on interfaces, patient-ventilator interaction and devices to provide NHFOV. We then move to the evidence-based review of parallel randomized clinical trial published so far. We provide both qualitative and quantitative synthesis of results for the two commonest outcomes, i.e. need for intubation and invasive ventilation and CO2 elimination. We also provide our protocol to use NHFOV together with other respiratory support modes and we provide suggestions on parameters boundaries and identification of patients to treat. We finally identify still open questions needing future research to optimize the use of NHFOV In preterm infants.

Non-Invasive Ventilatory Support in Preterm Neonates in the Delivery Room and the Neonatal Intensive Care Unit: A Short Narrative Review of What We Know in 2024

BACKGROUND

Guidelines recommend non-invasive ventilatory (NIV) support as first-line respiratory support mode in preterm infants as NIV is superior to intubation and mechanical ventilation in preventing death or bronchopulmonary dysplasia. However, with an ever-expanding variety of NIV modes available, there is much debate about which NIV modality should ideally be used, how, and when. The aims of this work were to summarise the evidence on different NIV modalities for both primary and secondary respiratory support: nCPAP, nasal high-flow therapy (nHFT), and nasal intermittent positive airway pressure ventilation (nIPPV), bi-level positive airway pressure (BiPAP), nasal high-frequency oscillatory ventilation (nHFOV), and nasally applied, non-invasive neurally adjusted ventilatory assist (NIV-NAVA) modes, with particular focus on their use in preterm infants.

SUMMARY

This is a narrative review with reference to published guidelines by European Consensus Guidelines on the Management of Respiratory Distress Syndrome: 2022 Update. nCPAP is currently the most commonly used primary and secondary NIV modality for premature infants. However, there is increasing evidence on the superiority of nIPPV over nCPAP. No beneficial effect was found for BiPAP over nCPAP. For the use of nHFT, nHFOV, and NIV-NAVA, more studies are needed to establish their place in neonatal respiratory care.

KEY MESSAGES

The superiority of nIPPV over nCPAP needs to be confirmed by contemporaneous trials comparing nCPAP to nIPPV at comparable mean airway pressures. Future trials should study NIV modalities in preterm infants with comparable respiratory pathology and indications, at comparable pressure settings and with different modes of synchronisation. Importantly, future trials should not exclude infants of the smallest gestational ages.

Nasal High-Frequency Oscillatory Ventilation Use in Romanian Neonatal Intensive Care Units-The Results of a Recent Survey

BACKGROUND

Nasal high-frequency oscillatory ventilation (nHFOV) has emerged as an effective initial and rescue noninvasive respiratory support mode for preterm infants with respiratory distress syndrome (RDS); however, little is known about nHFOV use in Romanian neonatal intensive care units (NICUs).

OBJECTIVES

We aimed to identify the usage extent and clinical application of nHFOV in Romania.

METHODS

A structured web-based questionnaire was designed to find the rate of nHFOV use and knowledge of this new method of noninvasive respiratory support in Romanian level III NICUs. Using multiple-choice, open-ended, and yes/no questions, we collected information on the NICU's size, noninvasive respiratory support modes used, nHFOV use, indications, settings, nasal interfaces, secondary effects, and equipment used. Descriptive statistics and comparisons were performed using IBM SPSS Statistics 26.0.

RESULTS

A total of 21/23 (91.3%) leaders from level III NICUs (median [IQR] number of beds of 10 [10-17.5]) responded to the survey. The most frequently used noninvasive ventilation modes were CPAP mode on mechanical ventilators (76.2%), followed by NIPPV (76.2%); heated, humidified high-flow nasal cannula (HHHFNC) (61.9%); and nHFOV (11/21 units; 52.4%). A total of 5/11 units reported frequent nHFOV use (in two or more newborns/month) in both term and preterm infants. The main indications reported for nHFOV use were CPAP failure (90.9%), hypercapnia (81.8%), and bronchopulmonary dysplasia (72.7%). Face/nasal masks and short binasal prongs are the most commonly used nasal interfaces (90.9% and 72.7%, respectively). Air leaks at the interface level (90.9%), thick secretions (81.8%), and airway obstruction (63.6%) were the most frequently mentioned adverse effects of nHFOV. Only three of the NICUs had a written protocol for nHFOV use. Most units not yet using nHFOV cited lack of equipment, experience, training, or insufficient information and evidence for the clinical use and outcome of nHFOV use in neonates as the main reasons for not implementing this noninvasive respiratory mode.

CONCLUSIONS

Our survey showed that nHFOV is already used in more than half of the Romanian level III NICUs to support term and preterm infants with respiratory distress despite a lack of consensus regarding indications and settings during nHFOV.

Non-invasive high-frequency ventilation in newborn infants with respiratory distress

BACKGROUND

Respiratory distress occurs in up to 7% of newborns, with respiratory support (RS) provided invasively via an endotracheal (ET) tube or non-invasively via a nasal interface. Invasive ventilation increases the risk of lung injury and chronic lung disease (CLD). Using non-invasive strategies, with or without minimally invasive surfactant, may reduce the need for mechanical ventilation and the risk of lung damage in newborn infants with respiratory distress.

OBJECTIVES

To evaluate the benefits and harms of nasal high-frequency ventilation (nHFV) compared to invasive ventilation via an ET tube or other non-invasive ventilation methods on morbidity and mortality in preterm and term infants with or at risk of respiratory distress.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL and three trial registries in April 2023.

SELECTION CRITERIA

Randomised controlled trials (RCTs), cluster- or quasi-RCTs of nHFV in newborn infants with respiratory distress compared to invasive or non-invasive ventilation.

DATA COLLECTION AND ANALYSIS

Two authors independently selected the trials for inclusion, extracted data, assessed the risk of bias, and undertook GRADE assessment.

MAIN RESULTS

We identified 33 studies, mostly in low- to middle-income settings, that investigated this therapy in 5068 preterm and 46 term infants. nHFV compared to invasive respiratory therapy for initial RS We are very uncertain whether nHFV reduces mortality before hospital discharge (RR 0.67, 95% CI 0.20 to 2.18; 1 study, 80 infants) or the incidence of CLD (RR 0.38, 95% CI 0.09 to 1.59; 2 studies, 180 infants), both very low-certainty. ET intubation, death or CLD, severe intraventricular haemorrhage (IVH) and neurodevelopmental disability (ND) were not reported. nHFV vs nasal continuous positive airway pressure (nCPAP) used for initial RS We are very uncertain whether nHFV reduces mortality before hospital discharge (RR 1.00, 95% CI 0.41 to 2.41; 4 studies, 531 infants; very low-certainty). nHFV may reduce ET intubation (RR 0.52, 95% CI 0.33 to 0.82; 5 studies, 571 infants), but there may be little or no difference in CLD (RR 1.35, 95% CI 0.80 to 2.27; 4 studies, 481 infants); death or CLD (RR 2.50, 95% CI 0.52 to 12.01; 1 study, 68 participants); or severe IVH (RR 1.17, 95% CI 0.36 to 3.78; 4 studies, 531 infants), all low-certainty evidence. ND was not reported. nHFV vs nasal intermittent positive-pressure ventilation (nIPPV) used for initial RS nHFV may result in little to no difference in mortality before hospital discharge (RR 1.86, 95% CI 0.90 to 3.83; 2 studies, 84 infants; low-certainty). nHFV may have little or no effect in reducing ET intubation (RR 1.33, 95% CI 0.76 to 2.34; 5 studies, 228 infants; low-certainty). There may be a reduction in CLD (RR 0.63, 95% CI 0.42 to 0.95; 5 studies, 307 infants; low-certainty). A single study (36 infants) reported no events for severe IVH. Death or CLD and ND were not reported. nHFV vs high-flow nasal cannula (HFNC) used for initial RS We are very uncertain whether nHFV reduces ET intubation (RR 2.94, 95% CI 0.65 to 13.27; 1 study, 37 infants) or reduces CLD (RR 1.18, 95% CI 0.46 to 2.98; 1 study, 37 participants), both very low-certainty. There were no mortality events before hospital discharge or severe IVH. Other deaths, CLD and ND, were not reported. nHFV vs nCPAP used for RS following planned extubation nHFV probably results in little or no difference in mortality before hospital discharge (RR 0.92, 95% CI 0.52 to 1.64; 6 studies, 1472 infants; moderate-certainty). nHFV may result in a reduction in ET reintubation (RR 0.42, 95% CI 0.35 to 0.51; 11 studies, 1897 infants) and CLD (RR 0.78, 95% CI 0.67 to 0.91; 10 studies, 1829 infants), both low-certainty. nHFV probably has little or no effect on death or CLD (RR 0.90, 95% CI 0.77 to 1.06; 2 studies, 966 infants) and severe IVH (RR 0.80, 95% CI 0.57 to 1.13; 3 studies, 1117 infants), both moderate-certainty. We are very uncertain whether nHFV reduces ND (RR 0.92, 95% CI 0.37 to 2.29; 1 study, 74 infants; very low-certainty). nHFV versus nIPPV used for RS following planned extubation nHFV may have little or no effect on mortality before hospital discharge (RR 1.83, 95% CI 0.70 to 4.79; 2 studies, 984 infants; low-certainty). There is probably a reduction in ET reintubation (RR 0.69, 95% CI 0.54 to 0.89; 6 studies, 1364 infants), but little or no effect on CLD (RR 0.88, 95% CI 0.75 to 1.04; 4 studies, 1236 infants); death or CLD (RR 0.92, 95% CI 0.79 to 1.08; 3 studies, 1070 infants); or severe IVH (RR 0.78, 95% CI 0.55 to 1.10; 4 studies, 1162 infants), all moderate-certainty. One study reported there might be no difference in ND (RR 0.88, 95% CI 0.35 to 2.16; 1 study, 72 infants; low-certainty). nHFV versus nIPPV following initial non-invasive RS failure nHFV may have little or no effect on mortality before hospital discharge (RR 1.44, 95% CI 0.10 to 21.33); or ET intubation (RR 1.23, 95% CI 0.51 to 2.98); or CLD (RR 1.01, 95% CI 0.70 to 1.47); or severe IVH (RR 0.47, 95% CI 0.02 to 10.87); 1 study, 39 participants, all low- or very low-certainty. Other deaths or CLD and ND were not reported.

AUTHORS' CONCLUSIONS

For initial RS, we are very uncertain if using nHFV compared to invasive respiratory therapy affects clinical outcomes. However, nHFV may reduce intubation when compared to nCPAP. For planned extubation, nHFV may reduce the risk of reintubation compared to nCPAP and nIPPV. nHFV may reduce the risk of CLD when compared to nCPAP. Following initial non-invasive respiratory support failure, nHFV when compared to nIPPV may result in little to no difference in intubation. Large trials, particularly in high-income settings, are needed to determine the role of nHFV in initial RS and following the failure of other non-invasive respiratory support. Also, the optimal settings of nHVF require further investigation.

Invasive and non-invasive ventilatory strategies for early and evolving bronchopulmonary dysplasia

In the age of surfactant and antenatal steroids, neonatal care has improved outcomes of preterm infants dramatically. Since the early 2000's neonatologists have strived to decrease bronchopulmonary dysplasia (BPD) by decreasing ventilator-associated lung injury and utilizing many novel modes of non-invasive respiratory support. After the initial success with nasal continuous positive airway pressure, it was established that discontinuing invasive ventilation early in favor of non-invasive respiratory support is the most effective way to reduce the incidence of BPD. In this review, we discuss the management of the preterm lung from the time of delivery, through the phases of respiratory distress syndrome (early BPD) and then evolving BPD. The goal remains to optimize respiratory support of the preterm lung while minimizing ventilator-associated lung injury and oxygen toxicity. A multidisciplinary approach involving the medical team and family is quintessential in reaching this goal and involves adequate respiratory support, optimizing nutrition and fluid balance as well as preventing infections.

The effect of non-invasive high-frequency oscillatory ventilation on the duration of non-invasive respiratory support in late preterm and term infants with transient tachypnea of the newborn: a randomized controlled trial

Nasal continuous positive airway pressure (nCPAP) is one of the most commonly used non-invasive respiratory support modes in neonates with transient tachypnea of the newborn (TTN). Non-invasive high-frequency oscillatory ventilation (nHFOV) is a non-invasive respiratory support mode that has been increasingly used in neonatal respiratory disorders. This prospective randomized controlled study compared the efficacy of nHFOV and nCPAP in reducing the duration of non-invasive respiratory support. Late preterm and term infants > 34 weeks' gestation were included in the study. The infants were randomly assigned to receive either nHFOV or nCPAP. Treatment was started with standard settings in both groups. Infants who met treatment failure criteria were switched to nasal intermittent mandatory ventilation for further positive-pressure support. A total of 60 infants were included in the study. Thirty of these infants were included in the nHFOV group and 30 were included in the nCPAP group. The median duration of non-invasive respiratory support was not significantly different between the two groups (21 h [IQR: 16-68] for nHFOV vs 15 h [IQR: 11-33] for nCPAP; p = 0.09). However, after adjusting for potential confounders, nHFOV was associated with a shorter duration of non-invasive respiratory support than nCPAP (adjusted mean difference: 16.3 h; 95% CI: 0.7 to 31.9; p = 0.04). nHFOV was well tolerated and did not increase the risk of complications.    Conclusion: Our findings suggest that nHFOV is an effective and safe ventilation mode for late preterm and term neonates with TTN.   Trial registry: Clinicaltrials.gov (NCT03006354). Date of registration: December 30, 2016. What is Known: • nHFOV is a ventilation model that has been increasingly used for the management of RDS. • TTN is one of the most common causes of neonatal respiratory distress. What is New: • nHFOV is associated with shorter duration of non-invasive respiratory support and duration of oxygen support. • nHFOV may be a safe and effective alternative to nCPAP for neonates with TTN.

Noninvasive high-frequency oscillatory ventilation versus nasal intermittent positive pressure ventilation for preterm infants as an extubation support: A systematic review and meta-analysis

OBJECTIVE

We aimed to explore whether noninvasive high-frequency oscillatory ventilation (NHFOV) could reduce the incidence of reintubation compared with nasal intermittent positive pressure ventilation (NIPPV) in the postextubation phase of preterm infants.

METHODS

Randomized controlled trials of NHFOV versus NIPPV were searched in PubMed, EMBASE, Cochrane Central, and MEDLINE. Meta-analysis was performed using Review Manager 5.3.

RESULTS

Four randomized controlled trials including 1138 preterm infants were included in this study. Compared with NIPPV, NHFOV reduced the incidence of reintubation in the post-extubation phase of preterm infants (p = 0.01, RR = 0.72, 95% confidence interval (CI): 0.56∼0.94), and no heterogeneity was found in the four studies (p = 0.55, I²  = 0%). In the sensitivity analysis, the result showed that there was no significant difference in the incidence of reintubation between NHFOV and NIPPV after excluding one study (p = 0. 05, RR = 0.76 95% CI: 0.58∼1.00), and no heterogeneity was found in the other three studies (p = 0.95, I²  = 0%). There was no statistical difference between NHFOV and NIPPV in BPD, air leak, IVH (≥Grade III) and mortality.

CONCLUSION

Among mechanically ventilated preterm infants, compared with NIPPV, NHFOV was potentially beneficial to reduce the incidence of reintubation after extubation and did not increase the risk of complications.

European Consensus Guidelines on the Management of Respiratory Distress Syndrome: 2022 Update

Respiratory distress syndrome (RDS) care pathways evolve slowly as new evidence emerges. We report the sixth version of "European Guidelines for the Management of RDS" by a panel of experienced European neonatologists and an expert perinatal obstetrician based on available literature up to end of 2022. Optimising outcome for babies with RDS includes prediction of risk of preterm delivery, appropriate maternal transfer to a perinatal centre, and appropriate and timely use of antenatal steroids. Evidence-based lung-protective management includes initiation of non-invasive respiratory support from birth, judicious use of oxygen, early surfactant administration, caffeine therapy, and avoidance of intubation and mechanical ventilation where possible. Methods of ongoing non-invasive respiratory support have been further refined and may help reduce chronic lung disease. As technology for delivering mechanical ventilation improves, the risk of causing lung injury should decrease, although minimising time spent on mechanical ventilation by targeted use of postnatal corticosteroids remains essential. The general care of infants with RDS is also reviewed, including emphasis on appropriate cardiovascular support and judicious use of antibiotics as being important determinants of best outcome. We would like to dedicate this guideline to the memory of Professor Henry Halliday who died on November 12, 2022.These updated guidelines contain evidence from recent Cochrane reviews and medical literature since 2019. Strength of evidence supporting recommendations has been evaluated using the GRADE system. There are changes to some of the previous recommendations as well as some changes to the strength of evidence supporting recommendations that have not changed. This guideline has been endorsed by the European Society for Paediatric Research (ESPR) and the Union of European Neonatal and Perinatal Societies (UENPS).

Non-invasive ventilatory support in neonates: An evidence-based update

Non-invasive ventilatory support (NIV) is considered the gold standard in the care of preterm infants with respiratory distress syndrome (RDS). NIV from birth is superior to mechanical ventilation (MV) for the prevention of death or bronchopulmonary dysplasia (BPD), with a number needed to treat between 25 and 35. Various methods of NIV are available, some of them extensively researched and with well proven efficacy, whilst others are needing further research. Nasal continuous positive airway pressure (nCPAP) has replaced routine invasive mechanical ventilation (MV) for the initial stabilization and the treatment of RDS. Choosing the most suitable form of NIV and the most appropriate patient interface depends on several factors, including gestational age, underlying lung pathophysiology and the local facilities. In this review, we present the currently available evidence on NIV as primary ventilatory support to preventing intubation and for secondary ventilatory support, following extubation. We review nCPAP, nasal high-flow cannula, nasal intermittent positive airway pressure ventilation, bi-level positive airway pressure, nasal high-frequency oscillatory ventilation and nasal neurally adjusted ventilatory assist modes. We also discuss most suitable NIV devices and patient interfaces during resuscitation of the newborn in the delivery room.

Surfactant without Endotracheal Tube Intubation (SurE) versus Intubation-Surfactant-Extubation (InSurE) in Neonatal Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

Neonatal respiratory distress syndrome (NRDS) is generally treated with surfactant by intubation-surfactant-extubation (InSurE) technique, an invasive method of surfactant administration. Surfactant without endotracheal tube intubation (SurE) is a noninvasive technique that avoids intubation and has been found to have improved the delivery of exogenous surfactants, thereby decreasing lung damage in neonates. This systematic review aimed to provide insights into the efficacy of SurE over InSurE in neonates who received respiratory support and to evaluate the progression and onset of concurrent diseases after treatment. The CENTRAL, PubMed, and Embase databases were searched for data collection. In all, 21 research articles were eligible, comprising 19,976 study participants. The data showed a significant reduction in the composite outcome of stage 2 necrotizing enterocolitis, bronchopulmonary dysplasia, and onset of hemodynamically significant patent ductus arteriosus when treated with SurE. The trend towards lower pneumothorax rates with SurE was also evident. These findings were robust due to the sensitivity analyses performed. There were no differences in the outcome of death or rates of other neonatal morbidities. Overall, SurE was identified as a better substitute for InSurE to treat neonates with RDS.

Lung volume distribution in preterm infants on non-invasive high-frequency ventilation

INTRODUCTION

Non-invasive high-frequency oscillatory ventilation (nHFOV) is an extension of nasal continuous positive airway pressure (nCPAP) support in neonates. We aimed to compare global and regional distribution of lung volumes during nHFOV versus nCPAP.

METHODS

In 30 preterm infants enrolled in a randomised crossover trial comparing nHFOV with nCPAP, electrical impedance tomography data were recorded in prone position. For each mode of respiratory support, four episodes of artefact-free tidal ventilation, each comprising 30 consecutive breaths, were extracted. Tidal volumes (V_T) in 36 horizontal slices, indicators of ventilation homogeneity and end-expiratory lung impedance (EELI) for the whole lung and for four horizontal regions of interest (non-gravity-dependent to gravity-dependent; EELI_NGD, EELI_midNGD, EELI_midGD, EELI_GD) were compared between nHFOV and nCPAP. Aeration homogeneity ratio (AHR) was determined by dividing aeration in non-gravity-dependent parts of the lung through gravity-dependent regions.

MAIN RESULTS

Overall, 228 recordings were analysed. Relative V_T was greater in all but the six most gravity-dependent lung slices during nCPAP (all p<0.05). Indicators of ventilation homogeneity were similar between nHFOV and nCPAP (all p>0.05). Aeration was increased during nHFOV (mean difference (95% CI)=0.4 (0.2 to 0.6) arbitrary units per kilogram (AU/kg), p=0.013), mainly due to an increase in non-gravity-dependent regions of the lung (∆EELI_NGD=6.9 (0.0 to 13.8) AU/kg, p=0.028; ∆EELI_midNGD=6.8 (1.2 to 12.4) AU/kg, p=0.009). Aeration was more homogeneous during nHFOV compared with nCPAP (mean difference (95% CI) in AHR=0.01 (0.00 to 0.02), p=0.0014).

CONCLUSION

Although regional ventilation was similar between nHFOV and nCPAP, end-expiratory lung volume was higher and aeration homogeneity was slightly improved during nHFOV. The aeration difference was greatest in non-gravity dependent regions, possibly due to the oscillatory pressure waveform. The clinical importance of these findings is still unclear.

Noninvasive High-Frequency Oscillatory Ventilation: A Retrospective Chart Review

OBJECTIVE

This study aimed to review the feasibility of nasal high-frequency oscillatory ventilation (NHFOV) in preventing reintubation in preterm infants.

STUDY DESIGN

This is a retrospective cohort study of all premature newborn infants placed on NHFOV in a single-center neonatal intensive care unit.

RESULTS

Twenty-seven patients (birth weight: 765 ± 186 g, gestational age: 28 ± 2 weeks) were commenced on NHFOV on 32 occasions. NHFOV was used immediately postextubation as the primary mode of noninvasive ventilation (NIV; prophylaxis) in 10 of 32 occasions and as "rescue" (failure of NCPAP or biphasic CPAP) in 22 of 32 occasions. Treatment with NHFOV was successful in 22 occasions (69%) while on 10 occasions (31%) reintubation was required within 72 hours. In the rescue group, there was significant reduction in the mean (standard deviation [SD]) number of apneas (0.9 ± 1.07 vs. 0.3 ± 0.29, p < 0.005), but there were no significant changes in the PCO₂ level (52 [ ±  9.8] vs. 52 [ ±  8.6] mm Hg, p = 0.8), or the FiO₂ requirement (0.39 ± 0.19 vs. 0.33 ± 0.10, p = 0.055) before and after commencing NHFOV, respectively.

CONCLUSION

The use of NHFOV is feasible as a prophylactic or rescue mode of NIV following extubation and was associated with decrease in the number of apneas without significant changes in PCO₂ or oxygen requirements. A well-designed randomized control trial is needed to determine the indications, clinical outcomes, and safety of this treatment modality.

KEY POINTS

· NHFOV is a new and evolving mode of noninvasive ventilation.. · The use of NHFOV is feasible as a prophylactic or rescue mode of noninvasive ventilation.. · A well-designed randomized control is needed to evaluate the efficacy and safety of NHFOV safe..

Novel Ventilation Strategies to Reduce Adverse Pulmonary Outcomes

Extremely preterm infants who must suddenly support their own gas exchange with lungs that are incompletely developed and lacking adequate amount of surfactant and antioxidant defenses are susceptible to lung injury. The decades-long quest to prevent bronchopulmonary dysplasia has had limited success, in part because of increasing survival of more immature infants. The process must begin in the delivery room with gentle assistance in establishing and maintaining adequate lung aeration, followed by noninvasive support and less invasive surfactant administration. Various modalities of invasive and noninvasive support have been used with varying degree of effect and are reviewed in this article.

Nasal high-frequency oscillatory ventilation versus nasal continuous positive airway pressure as primary respiratory support strategies for respiratory distress syndrome in preterm infants: a systematic review and meta-analysis

Nasal high-frequency oscillatory ventilation (NHFOV) is a new respiratory support strategy despite lacking of enough evidence in preterm infants with respiratory distress syndrome (RDS). The aim of the present systematic review was to explore whether NHFOV reduced the intubation rate as compared with nasal continuous positive airway pressure (NCPAP) as the primary respiratory support strategies in preterm infants with RDS. Medline, the Cochrane library, the Cochrane Controlled Trials Register, EMBASE, Chinese National Knowledge Infrastructure (CNKI), and Wanfang data Information Site were searched from inception to Jan 1, 2021(Prospero2019 CRD42019129316, date and name of registration: Apr 23,2019, The clinical effectiveness of NHFOV vs NCPAP for preterm babies with respiratory distress syndrome). Pooled data from clinically randomized controlled trials (RCTs) comparing NHFOV with NCPAP as the primary respiratory supporting strategies in preterm infants with RDS were performed using the fixed-effects models whenever no heterogeneity was shown. The primary outcome was intubation rate. Four randomized controlled trials involving 570 participants were included. Comparing with NCPAP, NHFOV resulted in less intubation (relative risk (RR) 0.44; 95% confidence interval (CI) 0.29-0.67, P = 0.0002), and heterogeneity was not found among the trials in the fixed-effects model (P = 0.78, I² = 0%). Similar result also appeared in sensitivity analysis after excluding one study with significant difference (RR 0.44; 95% CI 0.25-0.78, P = 0.005) (P = 0.58, I² = 0%).Conclusion: NHFOV decreased the intubation rate as compared with NCPAP as primary respiratory supporting strategies in preterm infants suffering from RDS. Future research should assess whether NHFOV can reduce the incidence of bronchopulmonary dysplasia (BPD) and intubation rate in preterm infants with BPD. Fund by Natural Science Foundation of Chongqing (cstc2020jcyj-msxmX0197), and "guan'ai" preterm Study Program of Renze Foundation of Beijing(K022). What is Known: • Nasal high-frequency oscillatory ventilation (NHFOV) has been described to be another advanced version of nasal continuous positive airway pressure (NCPAP). However, its beneficial effects among different studies as the primary modes in the early life of preterm infants with respiratory distress syndrome (RDS) were inconsistent. What is New: • Comparing with NCPAP, NHFOV decreases the risk of intubation as a primary respiratory supporting strategy in early life for preterm infants suffering from RDS.

Nasal High-Frequency Ventilation

Noninvasive high-frequency oscillatory (NHFOV) and percussive (NHFPV) ventilation represent 2 nonconventional techniques that may be useful in selected neonatal patients. We offer here a comprehensive review of physiology, mechanics, and biology for both techniques. As NHFOV is the technique with the wider experience, we also provided a meta-analysis of available clinical trials, suggested ventilatory parameters boundaries, and proposed a physiology-based clinical protocol to use NHFOV.

The high-risk factors of different severities of bronchopulmonary dysplasia (BPD) based on the national institute of child health and human development (NICHD) diagnosis criteria in 2018

Objective

To investigate the clinical characteristics of preterm infants with different severities of bronchopulmonary dysplasia (BPD) and disclose the high-risk factors of exacerbating BPD.

Methods

Collection of clinical data of 91 preterm infants admitted to the NICU and diagnosed with BPD, categorized in groups according to the disease severity: 41 mild cases,, 24 moderate cases, and 26 severe cases. Comparison and analysis of perinatal risk factors, treatment, complications and prognosis of the infants with different severity degrees.

Results

The severe group had a higher proportion of infants with congenital heart disease (CHD) higher than the moderate group (P < 0.05), and a higher ratio of pneumonia and mechanical ventilation (MV) ≥ seven days than the mild group (P < 0.05). The severe group also presented higher reintubation incidence than both the mild and moderate groups (P < 0.05). The groups presented different (P < 0.05) incidence rates of hemodynamically significant patent ductus arteriosus (hsPDA) . Ridit analysis suggested that the premature infants (PIs) with hsPDA, multiple microbial pulmonary infections, or Klebsiella pneumoniae pneumonia had more severe illness.

Conclusion

CHD, hsPDA, MV ≥ seven days, reintubation, pneumonia, especially multiple microbial pulmonary infections, and Klebsiella pneumoniae pneumonia are correlated with the severity of BPD and can be used as BPD progression predictor.

Non-invasive high-frequency oscillatory ventilation in preterm infants after extubation: a randomized, controlled trial

OBJECTIVE

To investigate the effectiveness and safety of non-invasive high-frequency oscillatory ventilation (NHFOV) in post-extubation preterm infants.

METHODS

This was a randomized, controlled trial. A total of 149 preterm infants aged between 25 to 34 weeks' gestational age with a birth weight of <1500 g who required invasive mechanical ventilation on admission were included. After extubation, they were randomized to the NHFOV group (n = 47), nasal intermittent positive pressure ventilation (NIPPV) group (n = 51), or nasal continuous positive airway pressure (NCPAP) group (n = 51). We compared the effectiveness and safety among these three groups.

RESULTS

A total of 139 preterm infants finally completed the study. The reintubation rate was significantly lower in the NHFOV group than in the other groups. The duration of non-invasive ventilation and the length of hospital stay in the NHFOV and NIPPV groups were significantly shorter than those in the NCPAP group. The incidence of bronchopulmonary dysplasia in the NHFOV and NIPPV groups was significantly lower than that in the NCPAP group. The NHFOV group had significantly less nasal injury than the NCPAP group.

CONCLUSION

As post-extubation respiratory support in preterm infants, NHFOV has a lower reintubation rate compared with NCPAP and NIPPV, without increasing the rate of complications.

Non-invasive High-Frequency Oscillatory Ventilation as Initial Respiratory Support for Preterm Infants With Respiratory Distress Syndrome

Objectives: The aim of this study was to investigate the safety and feasibility of nHFOV as initial respiratory support in preterm infants with RDS. Methods: This study retrospectively analyzed the clinical data of 244 premature infants with RDS who were treated in our hospital from January 2016 to January 2019 and divided into the nHFOV group (n = 115) and the BiPAP group (n = 129) based on the initial respiratory support method. Results: Respiratory outcomes showed that the rate of NIV failure during the first 72 hours of life in the nHFOV group was significantly lower than that in the BiPAP group. The time of NIV in the nHFOV group was significantly shorter than that in the BiPAP group. The time of supplemental oxygen in the nHFOV group was significantly shorter than that in the BiPAP group. The incidence of air leakage syndrome in the nHFOV group was significantly lower than that in the BiPAP group, and the length of hospital stay of the nHFOV group was also significantly shorter than that in the BiPAP group. Although the rate of infants diagnosed with BPD was similar between the two groups, the rate of severe BPD in the nHFOV group was significantly lower than that in the BiPAP group. Conclusion: This study showed that nHFOV as initial respiratory support for preterm infants with RDS was feasible and safe compared to BiPAP. Furthermore, nHFOV can reduce the need for IMV and reduce the incidence of severe BPD and air leak syndrome.

Nasal High-Frequency Oscillatory Ventilation in Preterm Infants with Moderate Respiratory Distress Syndrome: A Multicenter Randomized Clinical Trial

OBJECTIVE

To determine whether nasal high-frequency oscillatory ventilation (NHFOV) as a primary mode of respiratory support as compared with nasal continuous airway pressure (NCPAP) will reduce the need for invasive mechanical ventilation in preterm infants (260/7-336/7 weeks of gestational age [GA]) with respiratory distress syndrome (RDS).

METHODS

This multicenter randomized controlled trial was conducted in 18 tertiary neonatal intensive care units in China. A total of 302 preterm infants born at a GA of 260/7-336/7 weeks with a diagnosis of RDS were randomly assigned to either the NCPAP (n = 150) or the NHFOV (n = 152) group. The primary outcome was the need for invasive mechanical ventilation during the first 7 days after birth.

RESULTS

Treatment failure occurred in 15 of 152 infants (9.9%) in the -NHFOV group and in 26 of 150 infants (17.3%) in the NCPAP group (95% CI of risk difference: -15.2 to 0.4, p = 0.06). In the subgroup analysis, NHFOV resulted in a significantly lower rate of treatment failure than did NCPAP in the strata of 26+0/7-29+6/7weeks of GA (11.9 vs. 32.4%, 95% CI of risk difference: -39.3 to -1.7, p = 0.03) and birth weight <1,500 g (10.4 vs. 29.6%, 95% CI of risk difference: -33.8 to -4.6, p = 0.01). The rate of thick secretions causing an airway obstruction was higher in the NHFOV group than in the NCPAP group (13.8 vs. 5.3%, 95% CI of risk difference: 1.9-15.1, p = 0.01). No significant differences in other secondary outcomes were found between the NHFOV and NCPAP groups.

CONCLUSIONS

NHFOV was not superior to NCPAP with regard to the primary outcome when applied as the primary respiratory support for RDS in infants between 26+0/7 and 33+6/7 weeks of GA. In the subgroup analysis, NHFOV seemed to improve effectiveness than NCPAP in preterm infants <30 weeks of GA.

Non-invasive Respiratory Support of the Premature Neonate: From Physics to Bench to Practice

Premature births continue to rise globally with a corresponding increase in various morbidities among this population. Rates of respiratory distress syndrome and the consequent development of Bronchopulmonary Dysplasia (BPD) are highest among the extremely preterm infants. The majority of extremely low birth weight premature neonates need some form of respiratory support during their early days of life. Invasive modes of respiratory assistance have been popular amongst care providers for many years. However, the practice of prolonged invasive mechanical ventilation is associated with an increased likelihood of developing BPD along with other comorbidities. Due to the improved understanding of the pathophysiology of BPD, and technological advances, non-invasive respiratory support is gaining popularity; whether as an initial mode of support, or for post-extubation of extremely preterm infants with respiratory insufficiency. Due to availability of a wide range of modalities, wide variations in practice exist among care providers. This review article aims to address the physical and biological basis for providing non-invasive respiratory support, the current clinical evidence, and the most recent developments in this field of Neonatology.

Non-invasive respiratory support for preterm infants following extubation from mechanical ventilation. A narrative review and guideline suggestion

The recent introduction of different non-invasive ventilation modes for preterm has decreased the need for intubation, invasive ventilation and sedation. However, specific guidelines for each non-invasive mode are still lacking. This paper reviews available evidence for each of the commonly used noninvasive mode. Electronic search was carried out as a step forward towards a more comprehensive and detailed neonatal noninvasive ventilation guideline.

Nasal High-Frequency Oscillatory Ventilation in Preterm Infants With Respiratory Distress Syndrome and ARDS After Extubation: A Randomized Controlled Trial

BACKGROUND

Nasal high-frequency oscillatory ventilation (NHFOV) has been described as supplying the combined advantages of nasal CPAP (NCPAP) and HFOV. However, its effect on preterm infants needs to be further elucidated. Our objective was to assess whether NHFOV could reduce intubation and Pco₂ levels as compared with NCPAP during the postextubation phase in preterm infants.

METHODS

This was a single-center, randomized, controlled trial, and it was registered at clinicaltrials.gov (NCT03140891) and conducted between May 2017 and May 2018. Ventilated infants born at less than 37 weeks' gestational age and ready to be extubated were included and randomized to either the NHFOV or NCPAP group. Primary outcomes were the incidence of reintubation within 1 week and the Pco₂ level within 6 h.

RESULTS

A total of 206 preterm infants were included. Of them, 127 (61.7%) were diagnosed with respiratory distress syndrome, 53 (25.7%) with ARDS, and 26 (12.6%) with both respiratory distress syndrome and ARDS. Comparing with NCPAP, NHFOV significantly reduced the reintubation rate (16:87 vs 35:68; 95% CI, 0.18-0.70; P = .002), especially in the subgroup with a gestational age of ≤ 32 weeks (12:34 vs 25:20; 95% CI, 0.12-0.68; P = .004). The Pco₂ level was also significant lower in the NHFOV group (49.6 ± 8.7 vs 56.9 ± 9.9; 95% CI, -9.95 to -4.80; P = < .001). Moreover, NHFOV significantly reduced the reintubation rate in preterm infants with ARDS (10:33 vs 21:15; 95% CI, 0.08-0.57; P = .002).

CONCLUSIONS

NHFOV was shown to be superior to NCPAP in avoiding reintubation, especially in very preterm infants and those infants diagnosed with ARDS.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03140891; URL: www.clinicaltrials.gov.

Volume Targeted Ventilation and High Frequency Ventilation as the Primary Modes of Respiratory Support for ELBW Babies: What Does the Evidence Say?

Respiratory management of the extremely low birth weight (ELBW) newborn has evolved over time. Although non-invasive ventilation is being increasingly used for respiratory support in these ELBW infants, invasive ventilation still remains the primary mode in this population. Current ventilators are microprocessor driven and have revolutionized the respiratory support for these neonates synchronizing the baby's breath to ventilator breaths. High frequency ventilators with the delivery of tidal volumes less than the dead space have been introduced to minimize barotrauma and chronic lung disease. Despite these advances, the incidence of chronic lung disease has not decreased. There is still controversy regarding which mode is ideal as the primary mode of ventilation in ELBW infants. The most common modes seem to be pressure targeted conventional ventilation, volume targeted conventional ventilation and high frequency ventilation which includes high frequency oscillatory ventilation, high frequency jet ventilation and high frequency flow interrupter. In recent years, several randomized controlled trials and meta-analyses have compared volume vs. pressure targeted ventilation and high frequency ventilation. While volume targeted ventilation and high frequency ventilation does show promise, substantial practice variability among different centers persists. In this review, we weighed the evidence for each mode and evaluated which modes show promise as the primary support of ventilation in ELBW babies.

Three non-invasive ventilation strategies for preterm infants with respiratory distress syndrome: a propensity score analysis

INTRODUCTION

The present study was designed and conducted to compare the efficacy between nasal continuous positive airway pressure (NCPAP), nasal intermittent positive-pressure ventilation (NIPPV), and noninvasive high-frequency oscillatory ventilation (NHFOV) as the primary noninvasive ventilation in preterm infants with respiratory distress syndrome (RDS).

MATERIAL AND METHODS

This multicenter retrospective cohort study was performed using data from four tertiary neonatal intensive care units (NICUs) in China between 2016 and 2018. 512 preterm infants with RDS who received early non-invasive ventilation (NIV) were analyzed. Propensity score analysis with 1 : 1 matching was performed with the nearest neighbor matching method using calipers of width equal to 0.1 of the standard deviation of the logit of the propensity score. The primary outcome was the need for intubation and invasive mechanical ventilation (IMV) within the first 7 days after birth. Secondary outcomes were days of hospitalization, predischarge mortality, rate of retinopathy of prematurity (ROP) > stage II, rate of bronchopulmonary dysplasia (BPD) at 36 weeks post-menstrual age, rate of air leaks, rate of intraventricular hemorrhage (IVH) ≥ grade 3, and rate of necrotizing enterocolitis (NEC) ≥ stage II.

RESULTS

Propensity score matching identified 126 infants in each cohort (NHFOV vs. NIPPV), 96 infants in each cohort (NHFOV vs. NCPAP), 134 infants in each cohort (NIPPV vs. NCPAP) respectively. The need for IMV was significantly lower in the NHFOV as compared with NCPAP and NIPPV groups respectively (13/126 vs. 27/126, p = 0.016; 9/96 vs. 20/96, p = 0.027), while no difference was observed between NIPPV and NCPAP groups (25/134 vs. 25/134, p = 0.805). However, the number of days of hospitalization in NIPPV was significantly lower than that of the NCPAP group (24.8 ±14.6 days vs. 33.2 ±20.2 days p = 0.002). In subgroup analyses, the need for IMV was significantly lower in the NHFOV group than in the NCPAP and NIPPV group (7 : 79 vs. 15 : 74; 95% CI: 1.00-6.836; p = 0.044 and 11 : 102 vs. 22 : 98; 95% CI: 1.092-5.251; p = 0.026), and there was no difference between NIPPV and NCPAP in the preterm infants at ≤ 32 weeks' gestational age. There were no significant differences among three groups (p > 0.05 respectively) regarding secondary outcomes.

CONCLUSIONS

In this multicenter retrospective cohort study, NHFOV significantly reduced the need for IMV within the first 7 days as compared to NCPAP and NIPPV in the treatment of preterm infants with RDS without increasing the incidence of adverse events. However, NIPPV was not found to be superior to NCPAP for decreasing the need for IMV in the treatment of preterm infants with RDS.

The impact of preterm adversity on cardiorespiratory function

NEW FINDINGS

What is the topic of this review? We review the influence of prematurity on the cardiorespiratory system and examine the common sequel of alterations in oxygen tension, and immune activation in preterm infants. What advances does it highlight? The review highlights neonatal animal models of intermittent hypoxia, hyperoxia and infection that contribute to our understanding of the effect of stress on neurodevelopment and cardiorespiratory homeostasis. We also focus on some of the important physiological pathways that have a modulatory role on the cardiorespiratory system in early life.

ABSTRACT

Preterm birth is one of the leading causes of neonatal mortality. Babies that survive early-life stress associated with immaturity have significant prevailing short- and long-term morbidities. Oxygen dysregulation in the first few days and weeks after birth is a primary concern as the cardiorespiratory system slowly adjusts to extrauterine life. Infants exposed to rapid alterations in oxygen tension, including exposures to hypoxia and hyperoxia, have altered redox balance and active immune signalling, leading to altered stress responses that impinge on neurodevelopment and cardiorespiratory homeostasis. In this review, we explore the clinical challenges posed by preterm birth, followed by an examination of the literature on animal models of oxygen dysregulation and immune activation in the context of early-life stress.

Effect of high-frequency oscillation on pressure delivered by high flow nasal cannula in a premature infant lung model

OBJECTIVE

This study describes the effect of high-frequency oscillation on airway pressure generated by high flow nasal cannula (HFNC) in a premature infant lung model.

DESIGN/METHODS

A premature in 0.5 or 1.0 mL/cmH ₂ O, respiratory rate (RR) of 40 or 60 breaths per min, and tidal volume of 6 mL. Oscillation was achieved by passing the HFNC supply flow through a 3-way solenoid valve operating at 4, 6, 8, or 10 Hz. Airway pressure at the simulated trachea was recorded following equilibration of end-tidal CO ₂ both with and without oscillation.

RESULTS

Superimposing high-frequency oscillations onto HFNC resulted in an average decrease in mean airway pressure of 17.9% (P = .011). The difference between the maximum and minimum airway pressures, ∆ P _min-max, significantly increased as oscillation frequency decreased ( P < .001). Airway pressure during oscillation was 12.8% greater with the 1.0 vs the 0.5 mL/cmH ₂ O compliance at flows > 4 L/min ( P = .031). CO ₂ clearance was 13.1% greater with the 1.0 vs 0.5 mL/cmH ₂ O compliance at oscillation frequencies less than 8 Hz ( P = .015).

CONCLUSION

In this in-vitro study we demonstrate that delivered mean airway pressure decreases when applying high-frequency oscillation to HFNC, while still improving CO₂ clearance. The combination of improved CO ₂ clearance and reduced pressure delivery of this novel noninvasive modality may prove to be a useful improvement in the respiratory care of infants in respiratory distress.

Non-invasive high flow oscillatory ventilation in comparison with nasal continuous positive pressure ventilation for respiratory distress syndrome, a literature review

BACKGROUND

Noninvasive high-frequency oscillatory ventilation (NHFOV) keeps the lung open with add-on effective rhythmic oscillations in addition to allowing spontaneous breathing. This review aims at reconstructing the different pieces of available research articles and evidence into a more solid collective evidence for NHFOV in preterm infants with respiratory distress syndrome (RDS).

METHODS

A thorough systemic search was conducted in Medline, Embase, Web of Science, Google Scholar, CINAHL, and Cochrane. Randomized controlled trials (RCTs) on preterm infants with RDS comparing NHFOV with nasal continuous positive airway pressure (NCPAP) in terms of PCO₂ change, need for ventilation, duration of respiratory support, mortality air leak, or BPD were included. Data quality assessment and meta-analyses were carried out.

RESULTS

Five RCTs involving 270 preterm infants included in the review. PCO₂ relatively decreased on NHFOV (MD = 3.84, confidence interval (CI) 7.32-0.35, p = .03). On the other hand, relative risk (RR) of intubation was unquestionably decreased with NHFOV in comparison with NCPAP (RR  =  0.43, CI 0.25-0.75, p = .003) without statistical heterogeneity I² = 0%. Although the risk of mortality was less in NHFOV, the difference was statistically insignificant (RR = 0.72, CI 0.24-2.18, p = .56). Other outcomes reported in single studies only. Duration of respiratory support was significantly shorter in NHFOV compared with NCPAP (37.35 ± 8.96 versus 49.77 ± 10.33, p = .009), whereas air leak and BPD were reported in very few cases without a significant difference between the two interventions.

CONCLUSIONS

NHFOV improved the PCO₂ elimination and decreased the risk of intubation without a significant change in mortality compared with NCPAP.

Nasal Intermittent Mandatory Ventilation Versus Nasal Continuous Positive Airway Pressure Before and After Invasive Ventilatory Support

Continuous positive airway pressure (CPAP), noninvasive intermittent positive pressure ventilation (NIPPV), and heated humidified high-flow nasal cannula (HHFNC) are modes of noninvasive respiratory support used in neonatal practice. These modes of noninvasive respiratory support may obviate mechanical ventilation, prevent extubation failure, and reduce the risk of developing bronchopulmonary dysplasia. Although the physiologic bases of CPAP and HHFNC are well delineated, and their modes and practical application consistent, those of NIPPV are unproven and varied. Available evidence suggests that NIPPV is superior to CPAP as a primary and postextubation respiratory support in preterm infants.

Current insights in non-invasive ventilation for the treatment of neonatal respiratory disease

Deleterious consequences of the management of respiratory distress syndrome (RDS) with invasive ventilation have led to more in-depth investigation of non-invasive ventilation (NIV) modalities. NIV has significantly and positively altered the treatment outcomes and improved mortality rates of preterm infants with RDS. Among the different NIV modes, nasal intermittent positive pressure ventilation (NIPPV) has shown considerable benefits compared to nasal continuous positive airway pressure (NCPAP). Despite reports of heated humidified high-flow nasal cannula’s (HHHFNC) non-inferiority compared to NCPAP, some trials have been terminated due to high treatment failure rates with HHHFNC use. Moreover, RDS management with the combination of INSURE (INtubation SURfactant Extubation) technique and NIV ensures higher success rates. This review elaborates on the currently used various modes of NIV and novel techniques are also briefly discussed.

Carbon dioxide diffusion coefficient in noninvasive high-frequency oscillatory ventilation

OBJECTIVES

The carbon dioxide (CO₂ ) diffusion coefficient (DCO ₂ ) reflects CO ₂ removal during high-frequency oscillatory ventilation (HFOV). We hypothesized that despite leak flow during noninvasive HFOV (nHFOV) DCO ₂ continues to indicate ventilation efficacy.

METHODS

A neonatal airway model including CO₂ production and an adjustable oropharyngeal leak was connected to a ventilator via bi-nasal prongs. Pressures and gas flows were measured at prongs, trachea, and leak. Oscillatory tidal volumes below (V _{T trachea} ) and above the leak (V _{T prong} ) were calculated from tracheal and leak flows. DCO ₂ was calculated using V _{T trachea} (DCO _{2 trachea} ) and V _{T prong} (DCO _{2 prong} ) and compared with CO ₂ partial pressure (pCO ₂ ). Effects of leak flow (0, 5, or 10 L/min) on DCO ₂ were assessed at fixed pressure amplitudes or predefined oscillatory volumes under steady-state pCO ₂ conditions in the modeled lung.

RESULTS

DCO_{2 trachea} correlated strongly with pCO ₂ , independent of the leak flow level (P < 0.0001). DCO _{2 prong} correlated with pCO ₂ without and with moderate leak (P < 0.0001) but not with maximum leak (P = 0.1432). V _{T trachea} correlated with the quotient of tracheal pressure amplitude and frequency irrespective of the leak (P < 0.0001). Based on the pressure amplitude at prong level (A _prong ) V _{T trachea} continued to follow a linear model of which the slopes decreased with increasing leak flow. V _{T prong} correlated with the quotient of A _prong and frequency, irrespective of the leak (P < 0.0001).

CONCLUSIONS

DCO₂ obtained at the airway opening at prong level reflects ventilation efficacy during nHFOV even in the presence of moderate oropharyngeal leak.

Hazards to avoid in future neonatal studies of nasal high-frequency oscillatory ventilation: lessons from an early terminated trial

Objective

To investigate whether nasal high-frequency oscillatory ventilation (nHFOV) started immediately after extubation of mechanically ventilated very low birth weight infants reduces the partial pressure of carbon dioxide at 72 h after extubation in comparison with nasal continuous positive airway pressure. This randomised controlled single-centre trial aimed to include 68 preterm infants at high risk of extubation failure.

Results

Implementation of the study protocol was feasible. However, from 2015 to 2017, only six patients could be recruited, leading to early termination of the trial. The slow recruitment was due to the introduction of new strategies to avoid endotracheal mechanical ventilation, which reduced the number of eligible infants. Moreover, the included infants failed their extubation more often than anticipated, thereby increasing the required sample size. Based on our single-centre experience, we provide information for study planning and discuss the specific requirements for future trial protocols on nHFOV. The extubation of high-risk infants into nHFOV could well be beneficial, but a multicentric approach is necessary to investigate this hypothesis.

Trial Registration Clinicaltrials.gov NCT02340299, on 16 January 2015

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4268-2) contains supplementary material, which is available to authorized users.

Noninvasive high-frequency oscillatory ventilation as respiratory support in preterm infants: a meta-analysis of randomized controlled trials

BACKGROUND

Noninvasive high-frequency oscillatory ventilation (nHFOV), a relatively new modality, is gaining popularity despite scarce evidence. This meta-analysis was designed to evaluate the efficacy and safety of nHFOV as respiratory support in premature infants.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and Cochrane CENTRAL from inception of the database to January 2019. All published randomized controlled trials (RCTs) evaluating the effect of nHFOV therapy with nasal continuous positive airway pressure (nCPAP) or biphasic nCPAP (BP-CPAP) in newborns for respiratory support were included. All meta-analyses were performed using Review Manager 5.3.

RESULTS

A total of 8 RCTs involving 463 patients were included. The meta-analysis estimated a lower risk of intubation (relative risk = 0.50, 95% confidence interval of 0.36 to 0.70) and more effective clearance of carbon dioxide (weighted mean difference = - 4.61, 95% confidence interval of - 7.94 to - 1.28) in the nHFOV group than in the nCPAP/BP-CPAP group.

CONCLUSIONS

Our meta-analysis of RCTs suggests that nHFOV, as respiratory support in preterm infants, significantly remove carbon dioxide and reduce the risk of intubation compared with nCPAP/BP-CPAP. The appropriate parameter settings for different types of noninvasive high-frequency ventilators, the effect of nHFOV in extremely preterm infants, and the long-term safety of nHFOV need to be assessed in large trials.

Noninvasive high-frequency oscillatory ventilation versus nasal continuous positive airway pressure in preterm infants with respiratory distress syndrome: a randomized controlled trial

Background: Respiratory distress syndrome (RDS) is one of the main causes of mortality in premature neonates. Treatment of these neonates with invasive mechanical ventilation has side effects such as chronic pulmonary diseases. Noninvasive ventilation, such as nasal continuous positive airway pressure (NCPAP) and nasal high-frequency oscillation ventilation (NHFOV), has shown to reduce the burden of chronic lung disease. NHFOV is a promising new mode of noninvasive ventilation and may reduce the need for mechanical ventilation and reduce possible complications. In this study, we hypothesized that early NHFOV would reduce the need for invasive respiratory support in comparison to NCPAP in preterm neonates with RDS.Methods: One hundred twenty-four neonates between 28 to 34 weeks of gestational age (GA) with RDS hospitalized at Imam Khomeini Hospital, Ahvaz in 2016 were included in this randomized controlled study. The primary outcomes were the failure of NHFOV and NCPAP within 72 h after birth. The secondary outcomes were the duration of invasive ventilation and possible side effects.Results: Out of 124 neonates in this study, 63 and 61 neonates were studied in the NHFOV and NCPAP groups, respectively. There were no significant differences between NHFOV (6.5%) and NCPAP (14.1%) groups in terms of rates of primary consequences (p = .13). However, the duration of noninvasive ventilation in NHFOV was significantly less than that of NCPAP group (p = .01).Conclusion: In our study group, preterm infants from 28 to 34 weeks of GA, NHFOV did not reduce the need for mechanical ventilation during the first 72 h after birth compared to NCPAP; however, the duration of noninvasive ventilation in the NHFOV group was significantly shorter.

Nasal high-frequency oscillatory ventilation (nHFOV) versus nasal continuous positive airway pressure (NCPAP) as an initial therapy for respiratory distress syndrome (RDS) in preterm and near-term infants

BACKGROUND

Currently, various forms of non-invasive respiratory support have been used in the management of respiratory distress syndrome (RDS) in preterm neonates. However, nasal high-frequency oscillatory ventilation (nHFOV) has not yet been applied commonly as an initial treatment.

OBJECTIVES

This study was designed to investigate the efficacy and safety of nHFOV compared with nasal continuous positive airway pressure (NCPAP) in preterm and near-term infants with RDS.

METHODS

In a randomised clinical trial, a total of 68 neonates (gestational age (GA) between 30 and 36 weeks and 6 days) with a clinical diagnosis of RDS were randomly assigned to either the NCPAP (n=34) or the nHFOV (n=34) group. The primary outcome was the duration of non-invasive respiratory support (duration of using NCPAP or nHFOV).

RESULT

The median (IQR) duration of non-invasive respiratory support, was significantly shorter in the nHFOV group than that in the NCPAP group (20 (15-25.3) versus 26.5 (15-37.4) hours, respectively; p=0.02). The need for a ventilator occurred in 4 out of 34 (11.8%) neonates in the NCPAP group and in none of the neonates in the nHFOV group (p=0.03). In addition, intraventricular haemorrhage (IVH) occurred in nine cases (6.9%) in the NCPAP group and two cases (3.3%) in the nHFOV group, which showed a significant difference (p=0.04). The incidence of pneumothorax, chronic lung disease, pulmonary haemorrhage and necrotising enterocolitis was similar between the two groups.

CONCLUSION

This study showed that nHFOV significantly reduced the duration of non-invasive respiratory support and decreased the need for intubation compared with NCPAP in infants with RDS. Furthermore, nHFOV seems to reduce the incidence of IVH without increasing other complications.

TRIAL REGISTRATION NUMBER

IRCT2017062734782N1.

The Effect of Noninvasive High-Frequency Oscillatory Ventilation on Desaturations and Bradycardia in Very Preterm Infants: A Randomized Crossover Trial

Noninvasive high-frequency oscillatory ventilation compared with nasal continuous positive airway pressure significantly reduced the number of desaturations and bradycardia in preterm infants. However, noninvasive high-frequency oscillatory ventilation was associated with increased oxygen requirements and higher heart rates.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trial Registry: ACTRN12616001516471.

Nasal high-frequency oscillatory ventilation and CO2 removal: A randomized controlled crossover trial

OBJECTIVE

To compare short-term application of nasal high-frequency oscillatory ventilation (nHFOV) with nasal continuous positive airway pressure (nCPAP).

WORKING HYPOTHESIS

nHFOV improves CO₂ removal with respect to nCPAP in preterm infants needing noninvasive respiratory support and persistent oxygen supply after the first 72 h of life.

STUDY DESIGN

Multicenter non-blinded prospective randomized crossover study.

PATIENT SELECTION

Thirty premature infants from eight tertiary neonatal intensive care units, of mean ± SD 26.4 ± 1.8 weeks of gestational age and 921 ± 177 g of birth weight.

METHODOLOGY

Infants were randomly allocated in a 1:1 ratio to receive a starting treatment mode of either nCPAP or nHFOV delivered by the ventilator CNO (Medin, Germany), using short binasal prongs of appropriate size. A crossover design with four 1-h treatment periods was used, such that each infant received both treatments twice. The primary outcome was the mean transcutaneous partial pressure of CO₂ (TcCO₂ ) value during the 2-h cumulative period of nHFOV compared with the 2-h cumulative period of nCPAP.

RESULTS

Significantly lower TcCO₂ values were observed during nHFOV compared with nCPAP: 47.5 ± 7.6 versus 49.9 ± 7.2 mmHg, respectively, P = 0.0007. A different TcCO₂ behavior was found according to the random sequence: in patients starting on nCPAP, TcCO₂ significantly decreased from 50.0 ± 8.0 to 46.6 ± 7.5 mmHg during nHFOV (P = 0.001). In patients starting on nHFOV, TcCO₂ slightly increased from 48.5 ± 7.8 to 49.9 ± 6.7 mmHg during nCPAP (P = 0.13).

CONCLUSIONS

nHFOV delivered through nasal prongs is more effective than nCPAP in improving the elimination of CO₂ .

2017 pediatric pulmonology year in review part 2-neonatology

The articles published in 2017 in topic areas relevant to neonatal pulmonology are reviewed in Part 2 of the Year-in-Review.

Pediatric Pulmonology year in review 2017: Part 3

Pediatric Pulmonology publishes original research, reviews, and case reports related to a wide range of children's respiratory disorders. We here summarize the past year's publications in our major topic areas, in the context of selected literature in these areas from other journals relevant to our discipline. This review (Part 3 of a 5-part series) covers selected articles on asthma, physiology/lung function testing, and respiratory infections.

Non-invasive high-frequency oscillatory ventilation versus nasal continuous positive airway pressure in preterm infants with respiratory distress syndrome: Study protocol for a multi-center prospective randomized controlled trial

BACKGROUND

Invasive mechanical ventilation (IMV) is associated with the development of adverse pulmonary and non-pulmonary outcomes in very premature infants. Various modes of non-invasive respiratory support are increasingly being used to decrease the incidence of bronchopulmonary dysplasia. The aim of this trial is to compare the effect of non-invasive high-frequency oscillatory ventilation (NHFOV) and nasal continuous positive airway pressure (NCPAP) in preterm infants with respiratory distress syndrome (RDS) as a primary non-invasive ventilation support mode.

METHODS/DESIGN

In this multi-center randomized controlled trial, 300 preterm infants born at a gestational age of 266/7 to 336/7 weeks with a diagnosis of RDS will be randomized to NHFOV or NCPAP as a primary mode of non-invasive respiratory support. The study will be conducted in 18 tertiary neonatal intensive care units in China. The primary outcome is the need for IMV during the first 7 days after enrollment in preterm infants randomized to the two groups. The prespecified secondary outcomes include days of hospitalization, days on non-invasive respiratory support, days on IMV, days on supplemental oxygen, mortality, need for a surfactant, severe retinopathy of prematurity requiring laser treatment or surgery, patent ductus arteriosus needing ligation, bronchopulmonary dysplasia, abdominal distention, air leak syndromes, intraventricular hemorrhage (≥ grade 3), spontaneous intestinal perforation, necrotizing enterocolitis (≥II stage), and nasal trauma. Other secondary outcomes include Bayley Scales of Infant Development at 18-24 months of corrected age.

DISCUSSION

In recent decades, several observational studies have compared the effects of NHFOV and NCPAP in neonates as a rescue mode or during weaning from IMV. To our knowledge, this will be the first multi-center prospective, randomized controlled trial to evaluate NHFOV as a primary mode in preterm infants with RDS in China or any other part of the world. Our trial may help to establish guidelines for NHFOV in preterm infants with RDS to minimize the need for IMV, and to decrease the significant pulmonary and non-pulmonary morbidities associated with IMV.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03099694 . Registered on 4 April 2017.

Nasal high-frequency oscillatory ventilation inhibits gastroesophageal reflux in the neonatal period

Nasal high-frequency oscillatory ventilation (nHFOV) in neonates is increasingly considered due to enhanced alveolar ventilation, absence of patient-ventilator asynchrony and lessened ventilator-induced lung injury. Although any type of non-invasive respiratory support can lead to gastric distension via esophageal air passage and thus promote gastroesophageal refluxes (GERs), we have shown that nasal continuous positive airway pressure (CPAP; 6 cmH₂O) and intermittent positive pressure ventilation (15/4 cmH₂O) conversely inhibit GERs in lambs. The current objective was to test the hypothesis that nHFOV also inhibits GERs compared to spontaneous ventilation without respiratory support. Eight lambs underwent five hours of polysomnographic and esophageal multichannel intraluminal impedance pHmetry recordings to assess GERs and air passage into the esophagus, with and without nHFOV (mean airway pressure = 8 cmH₂O, oscillation frequency = 8 Hz, amplitude ≈ 20 cmH₂O and I:E = 1:2). Results revealed that GERs were decreased with nHFOV (p = .03), despite an increase in gas-containing swallows (p = .01). In conclusion, similarly to nasal CPAP and intermittent positive pressure ventilation, nHFOV inhibits GERs in newborn lambs.

Extubation from high-frequency oscillatory ventilation in extremely low birth weight infants: a prospective observational study

OBJECTIVE

To evaluate if weaning from high-frequency oscillatory ventilation (HFOV) directly to a non-invasive mode of respiratory support is feasible and results in successful extubation in extremely low birth weight (ELBW) infants.

DESIGN

Prospective observational study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

One hundred and eight ELBW infants of 26.2±1.4 weeks of gestational age (GA) directly extubated from HFOV.

INTERVENTIONS

All infants were managed with elective HFOV and received surfactant after a recruitment HFOV manoeuvre. Extubation was attempted at mean airways pressure (MAP) ≤6 cm H₂O with FiO₂ ≤0.25. After extubation, all infants were supported by nasal continuous positive airway pressure (6-8 cm H₂O).

MAIN OUTCOME MEASURES

Extubation failure (clinical deterioration requiring reintubation) was defined as shorter than 7 days.

RESULTS

Ninety patients (83%) were successfully extubated and 18 (17%) required reintubation. No significant differences were found between the two groups in terms of birth weight, day of life and weight at the time of extubation. Multivariable analysis showed that GA (OR 1.71; 95% CI 1.04, 2.08) and higher MAP prior to surfactant (OR 1.51; 95% CI 1.06, 2.15) were associated with successful extubation.

CONCLUSIONS

In ELBW infants, direct extubation from HFOV at MAP ≤6 cm H₂O with FiO₂ ≤0.25 is feasible. Our extubation success rate (83%) is higher than conventional mechanical ventilation in this very vulnerable class of infants.

Nasal high-frequency oscillatory ventilation impairs heated humidification: A neonatal bench study

OBJECTIVE

Nasal high-frequency oscillatory ventilation (nHFOV) is a novel mode of non-invasive ventilation used in neonates. However, upper airway obstructions due to viscous secretions have been described as specific adverse effects. We hypothesized that high-frequency oscillations reduce air humidity in the oropharynx, resulting in upper airway desiccation. Therefore, we aimed to investigate the effects of nHFOV ventilatory settings on oropharyngeal gas conditions.

METHODS

NHFOV or nasal continuous positive airway pressure (nCPAP) was applied, along with heated humidification, to a previously established neonatal bench model that simulates oropharyngeal gas conditions during spontaneous breathing through an open mouth. A digital thermo-hygro sensor measured oropharyngeal temperature (T) and humidity at various nHFOV frequencies (7, 10, 13 Hz), amplitudes (10, 20, 30 cmH₂ O), and inspiratory-to-expiratory (I:E) ratios (25:75, 33:66, 50:50), and also during nCPAP.

RESULTS

Relative humidity was always >99%, but nHFOV resulted in lower mean T and absolute humidity (AH) in comparison to nCPAP (P < 0.001). Specifically, decreasing the nHFOV frequency and increasing nHFOV amplitude caused a decline in T and AH (P < 0.001). Mean T and AH were highest during nCPAP (T 34.8 ± 0.6°C, AH 39.3 ± 1.3 g · m^-3 ) and lowest during nHFOV at a frequency of 7 Hz and an amplitude of 30 cmH₂ O (T 32.4 ± 0.3°C, AH 34.7 ± 0.5 g · m^-3 ). Increasing the I:E ratio also reduced T and AH (P = 0.03).

CONCLUSION

Intensified nHFOV settings with low frequencies, high amplitudes, and high I:E ratios may place infants at an increased risk of upper airway desiccation. Future studies should investigate strategies to optimize heated humidification during nHFOV.