Non-invasive high-frequency oscillatory ventilation in neonates: review of physiology, biology and clinical data

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.

The effect of NHFOV on hemodynamics in mild and moderately preterm neonates: a randomized clinical trial

The aim of this study is to study cardio-respiratory effects of nasal high-frequency oscillatory ventilation (NHFOV) vs. NCPAP as an initial mode of ventilation in moderate-late-preterm infants. A randomized controlled trial was conducted in NICU of Alexandria University Maternity Hospital (AUMH). One-hundred late-moderate-preterm infants were randomly assigned to either NHFOV-group (n = 50) or NCPAP-group (n = 50). For both groups, functional echocardiography was performed in the first 24 h to detect hemodynamic changes and respiratory outcome was monitored throughout the hospital stay. The main outcomes were hemodynamic measurements and myocardial function using functional echocardiography of those infants along with the respiratory outcome and complications. Kaplan-Meier survival plot was used representing time course of NCPAP and NHFOV failure. Left ventricular output values were not significantly different in both groups with median 202 ml/kg /min and IQR (176-275) in NCPAP-group and 226 ml/kg/min with IQR (181-286) in NHFOV group. Nevertheless, ejection fraction and fractional shortening were significantly higher in NHFOV-group with P 0.001. The time to weaning, the time to reach 30%-FIO2, the need for invasive ventilation, oxygen support duration, and maximal-FIO2 were significantly more in NCAPAP group.     Conclusion: NHFOV is an effective and promising tool of non-invasive-ventilation which can be used as a primary modality of respiratory support in preterm infants with variable forms of respiratory distress syndrome without causing detrimental effect on hemodynamics or significant respiratory complications.     Trial registration: NCT05706428 (registered on January 21, 2023). What is Known: • NHFOV might be beneficial as a secondary mode of ventilation and might have an impact on hemodynamics. What is New: • NHFOV can be used as an initial mode of ventilation with CDP beyond the reported pressure limits of CPAP without causing neither CO2 retention nor adverse hemodynamic consequences.

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 oscillatory ventilation (NHFOV) versus nasal continuous positive airway pressure (NCPAP) for preterm infants: a systematic review and meta-analysis

OBJECTIVE

To compare the efficacy and safety of non-invasive high-frequency oscillatory ventilation (NHFOV) and nasal continuous positive airway pressure (NCPAP) in preterm infants.

DESIGN

The study conducted a comprehensive analysis across three databases, namely EMBASE, MEDLINE and Cochrane Central, to identify randomised controlled trials comparing NHFOV and NCPAP. Statistical analysis was performed using Review Manager V.5.3 software.

MAIN OUTCOMES MEASURES

The primary outcomes of the study were the intubation or reintubation rate in the NHFOV and NCPAP groups. Additionally, secondary outcomes included the partial pressure of carbon dioxide levels and major complications associated with non-invasive respiratory support ventilation.

RESULTS

Ten randomised controlled studies, involving 2031 preterm infants, were included in this meta-analysis. When compared with NCPAP, NHFOV demonstrated a significant reduction in the intubation or reintubation rate (p<0.01, relative risk=0.45, 95% CI 0.37 to 0.55), and there was no statistical difference in related complications.

CONCLUSION

In preterm infants, NHFOV appears to be an effective intervention for decreasing the intubation or reintubation rate compared with NCPAP, with no increase in associated complications.

TRIAL REGISTRATION NUMBER

CRD42023403968.

Quantitative Lung Ultrasonography to Guide Surfactant Therapy in Neonates Born Late Preterm and Later

Importance

Surfactant administration may be needed in late preterm through full-term neonates, but the pathophysiology of their respiratory failure can be different from that of early preterm neonates. The lung ultrasonography score (LUS) is accurate to guide surfactant replacement in early preterm neonates, but to our knowledge, it has not yet been studied in the late preterm through full-term neonatal population.

Objective

To assess whether LUS is equally accurate to predict surfactant need in late preterm through full-term neonates as in early preterm neonates.

Design, Setting, and Participants

This prospective, international, multicenter diagnostic study was performed between December 2022 and November 2023 in tertiary academic neonatal intensive care units in France, Italy, Spain, and the US. Late preterm through full-term neonates (≥34 weeks' gestation) with respiratory failure early after birth were enrolled.

Exposure

Point-of-care lung ultrasonography to calculate the neonatal LUS (range, 0-18, with higher scores indicating worse aeration), which was registered in dedicated research databases and unavailable for clinical decision-making.

Main Outcomes and Measures

The main outcomes were the area under the curve (AUC) in receiver operating characteristic analysis and derived accuracy variables, considering LUS as a replacement for other tests (ie, highest global accuracy) and as a triage test (ie, highest sensitivity). Sample size was calculated to assess noninferiority of LUS to predict surfactant need in the study population compared with neonates born more prematurely. Correlations of LUS with the ratio of hemoglobin oxygen saturation as measured by pulse oximetry (SpO2) to fraction of inspired oxygen (FiO2) and with the oxygen saturation index (OSI) were assessed.

Results

A total of 157 neonates (96 [61.1%] male) were enrolled and underwent lung ultrasonography at a median of 3 hours (IQR, 2-7 hours) of life; 32 (20.4%) needed surfactant administration (pretest probability, 20%). The AUC was 0.87 (95% CI, 0.81-0.92). The highest global accuracy and sensitivity were reached for LUS values higher than 8 or 4 or lower, respectively. Subgroup analysis gave similar diagnostic accuracy in neonates born late preterm (AUC, 0.89; 95% CI, 0.81-0.97; n = 111) and early term and later (AUC, 0.84; 95% CI, 0.73-0.96; n = 46). After adjusting for gestational age, LUS was significantly correlated with SpO2:FiO2 (adjusted β, -10.4; 95% CI, -14.0 to -6.7; P < .001) and OSI (adjusted β, 0.2; 95% CI, 0.1-0.3; P < .001).

Conclusions and Relevance

In this diagnostic study of late preterm through full-term neonates with respiratory failure early after birth, LUS accuracy to predict surfactant need was not inferior to that observed in earlier preterm neonates. An LUS higher than 8 was associated with highest global accuracy (replacement test), suggesting that it can be used to guide surfactant administration. An LUS value of 4 or lower was associated with the highest sensitivity (triage test), suggesting it is unlikely for this population to need surfactant.

Nasal high frequency oscillatory highflow therapy in preterm infants: A randomized crossover trial

OBJECTIVES

To assess the clinical efficacy, safety, and potential physiological mechanisms of highflow therapy with superimposed high frequency oscillations ("osciflow").

STUDY DESIGN

In this prospective, randomized, single center crossover trial, 30 preterm infants were randomized to receive osciflow or highflow therapy first, each for 180 min. During osciflow, an oscillatory amplitude of 20 mbar and a frequency of 6 Hz were set. The flow rate was 4 L/min during both interventions. Primary outcome was the paired difference in the combined number of desaturations (SpO2  < 80%) and bradycardia (heart rate <80 beats per min) between interventions. Safety outcomes included nasal trauma, pneumothorax and treatment failure, and a pain score was assessed. In 20 infants, electrical impedance tomography (EIT) recordings were performed to evaluate oscillatory (VOsc ) and tidal volumes (VT ) at the lung level.

RESULTS

Infants with a mean (SD) postnatal age of 33.1 ± 1.2 weeks were included. The median (IQR) number of episodes of desaturation and bradycardia was 19.5 (6-49) during osciflow and 26 (6-44) during highflow therapy (paired difference -2; IQR -10 to 9; p = .37). There were no differences in safety outcomes and pain scores. During osciflow, EIT recordings showed a signal at 6 Hz, which was not detectable during highflow. Corresponding mean (SD) VOsc /VT ratio was 9% (±5%).

CONCLUSIONS

In preterm infants, osciflow did not reduce the number of desaturations and bradycardia compared with highflow therapy. Although VOsc were transmitted to the lung during osciflow, their magnitude was small. Osciflow was safe and well tolerated.

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.

A Nomogram for Predicting Extubation Failure in Preterm Infants with Gestational Age Less than 29 Weeks

INTRODUCTION

How to avoid reintubations in prematurity remains a hard nut. This study aimed to develop and validate a nomogram for predicting extubation failure in preterm infants who received different modes of noninvasive ventilation as post-extubation support.

METHODS

This was a secondary analysis of pre-existing data from a large multicenter RCT combined with a multicenter retrospective investigation in three tertiary referral NICUs in China. The training cohort consisted of extubated infants from the RCT and the validation cohort included neonates admitted to the three NICUs in the last 5 years. The nomogram was developed through univariate and multivariate logistic regression analyses of peri-extubation clinical variables.

RESULTS

A total of 432 and 183 preterm infants (25 weeks ≤ gestational age [GA] <29 weeks) were, respectively, included in the training cohort and the validation cohort. Lower birth weight, lower Apgar 5-min score, lower postmenstrual age at extubation, lower PO2 and higher PCO2 before extubation, and continuous positive airway pressure rather than nasal intermittent positive pressure ventilation or noninvasive high-frequency oscillatory ventilation after extubation were associated with higher risks of extubation failure (p < 0.05), on which the nomogram was established. In both the training cohort and the validation cohort, the nomogram demonstrated good predictive accuracy (area under the receiver operating characteristic curve = 0.744 and 0.826); the Hosmer-Lemeshow test (p = 0.192 and 0.401) and the calibration curve (R2 = 0.195 and 0.307) proved a good fitness and conformity; and the decision curve analysis showed significant net benefit at the best threshold (p = 0.201).

CONCLUSION

This nomogram could serve as a good decision-support tool when predicting extubation failure in preterm infants with GA less than 29 weeks.

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.

Lung volume changes during apnoeas in preterm infants

OBJECTIVE

Mechanisms of non-invasive high-frequency oscillatory ventilation (nHFOV) in preterm infants are unclear. We aimed to compare lung volume changes during apnoeas in preterm infants on nHFOV and nasal continuous positive airway pressure (nCPAP).

METHODS

Analysis of electrical impedance tomography (EIT) data from a randomised crossover trial comparing nHFOV with nCPAP in preterm infants at 26-34 weeks postmenstrual age. EIT data were screened by two reviewers to identify apnoeas ≥10 s. End-expiratory lung impedance (EELI) and tidal volumes (V_T) were calculated before and after apnoeas. Oxygen saturation (SpO₂) and heart rate (HR) were extracted for 60 s after apnoeas.

RESULTS

In 30 preterm infants, 213 apnoeas were identified. During apnoeas, oscillatory volumes were detectable during nHFOV. EELI decreased significantly during apnoeas (∆EELI nCPAP: -8.0 (-11.9 to -4.1) AU/kg, p<0.001; ∆EELI nHFOV: -3.4 (-6.5 to -0.3), p=0.03) but recovered over the first five breaths after apnoeas. Compared with before apnoeas, V_T was increased for the first breath after apnoeas during nCPAP (∆V_T: 7.5 (3.1 to 11.2) AU/kg, p=0.001). Falls in SpO₂ and HR after apnoeas were greater during nCPAP than nHFOV (mean difference (95% CI): SpO₂: 3.6% (2.7 to 4.6), p<0.001; HR: 15.9 bpm (13.4 to 18.5), p<0.001).

CONCLUSION

Apnoeas were characterised by a significant decrease in EELI which was regained over the first breaths after apnoeas, partly mediated by a larger V_T. Apnoeas were followed by a considerable drop in SpO₂ and HR, particularly during nCPAP, leading to longer episodes of hypoxemia during nCPAP. Transmitted oscillations during nHFOV may explain these benefits.

TRIAL REGISTRATION NUMBER

ACTRN12616001516471.

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.

Comparison of nasal intermittent positive pressure ventilation and bubble CPAP with an in-line high-frequency interrupter in a premature infant lung model

INTRODUCTION

Noninvasive ventilation has become a staple in the care of premature infants. However, failure rates continue to be high in this population. Modifications to noninvasive support, such as nasal intermittent positive pressure ventilation (NIPPV), are used clinically to reduce such failure. Previous in vitro studies have shown improved CO₂ clearance when superimposing high-frequency oscillations onto bubble continuous positive airway pressure (BCPAP).

OBJECTIVE

To compare the CO₂ clearance of NIPPV to BCPAP with an in-line high-frequency interrupter (HFI) in a premature infant lung model.

METHODS

A premature infant lung model was connected to either a Dräger VN500 for delivery of NIPPV or a BCPAP device with superimposed high-frequency oscillations generated by an in-line HFI. Change in end-tidal CO₂  (ETCO₂ ) and mean airway pressure at the simulated trachea were measured and compared for both noninvasive modalities.

RESULTS

Superimposing HF oscillations onto BCPAP with an in-line HFI resulted in improved CO₂ clearance relative to BCPAP alone for all tested oscillation frequencies at all CPAP levels (p < 0.001). NIPPV also resulted in improved CO₂  clearance relative to nasal CPAP (NCPAP) alone (p < 0.001). Among the tested settings, BCPAP with an in-line HFI resulted in decreased ETCO₂ relative to BCPAP ranging from -14% to -36%, while NIPPV resulted in decreased ETCO₂  relative to NCPAP ranging from -2% to -12%.

CONCLUSION

Superimposing high-frequency oscillations onto BCPAP using a novel in-line HFI was found to be more effective at clearing CO₂ than NIPPV in a premature infant lung model.

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.

Non-invasive respiratory support in preterm infants

Survival of preterm infants has increased steadily over recent decades, primarily due to improved outcomes for those born before 28 weeks of gestation. However, this has not been matched by similar improvements in longer-term morbidity. One of the key long-term sequelae of preterm birth remains bronchopulmonary dysplasia (also called chronic lung disease of prematurity), contributed primarily by the effect of early pulmonary inflammation superimposed on immature lungs. Non-invasive modes of respiratory support have been rapidly introduced providing modest success in reducing the incidence of bronchopulmonary dysplasia when compared with invasive mechanical ventilation, and improved clinical practice has been reported from population-based studies. We present a comprehensive review of the key modes of non-invasive respiratory support currently used in preterm infants, including their mechanisms of action and evidence of benefit from clinical trials.

Noninvasive High-Frequency Oscillatory Ventilation vs Nasal Continuous Positive Airway Pressure vs Nasal Intermittent Positive Pressure Ventilation as Postextubation Support for Preterm Neonates in China: A Randomized Clinical Trial

Importance

Several respiratory support techniques are available to minimize the use of invasive mechanical ventilation (IMV) in preterm neonates. It is unknown whether noninvasive high-frequency oscillatory ventilation (NHFOV) is more efficacious than nasal continuous positive airway pressure (NCPAP) or nasal intermittent positive pressure ventilation (NIPPV) in preterm neonates after their first extubation.

Objective

To test the hypothesis that NHFOV is more efficacious than NCPAP or NIPPV in reducing IMV after extubation and until neonatal intensive care unit discharge among preterm neonates.

Design, Setting, and Participants

This multicenter, pathophysiology-based, assessor-blinded, 3-group, randomized clinical trial was conducted in 69 tertiary referral neonatal intensive care units in China, recruiting participants from December 1, 2017, to May 31, 2021. Preterm neonates who were between the gestational age of 25 weeks plus 0 days and 32 weeks plus 6 days and were ready to be extubated were randomized to receive NCPAP, NIPPV or NHFOV. Data were analyzed on an intention-to-treat basis.

Interventions

The NCPAP, NIPPV, or NHFOV treatment was initiated after the first extubation and lasted until discharge.

Main Outcomes and Measures

Primary outcomes were total duration of IMV, need for reintubation, and ventilator-free days. These outcomes were chosen to describe the effect of noninvasive ventilation strategy on the general need for IMV.

Results

A total of 1440 neonates (mean [SD] age at birth, 29.4 [1.8] weeks; 860 boys [59.7%]) were included in the trial. Duration of IMV was longer in NIPPV (mean difference, 1.2; 95% CI, 0.01-2.3 days; P = .04) and NCPAP (mean difference, 1.5 days; 95% CI, 0.3-2.7 days; P = .01) compared with NHFOV. Neonates who were treated with NCPAP needed reintubations more often than those who were treated with NIPPV (risk difference: 8.1%; 95% CI, 2.9%-13.3%; P = .003) and NHFOV (risk difference, 12.5%; 95% CI, 7.5%-17.4%; P < .001). There were fewer ventilator-free days in neonates treated with NCPAP than in those treated with NIPPV (median [25th-75th percentile] difference, -3 [-6 to -1] days; P = .01). There were no differences between secondary efficacy or safety outcomes, except for the use of postnatal corticosteroids (lower in NHFOV than in NCPAP group; risk difference, 7.3%; 95% CI, 2.6%-12%; P = .002), weekly weight gain (higher in NHFOV than in NCPAP group; mean difference, -0.9 g/d; 95% CI, -1.8 to 0 g/d; P = .04), and duration of study intervention (shorter in NHFOV than in NIPPV group; median [25th-75th percentile] difference, -1 [-3 to 0] days; P = .01).

Conclusions and Relevance

Results of this trial indicated that NHFOV, if used after extubation and until discharge, slightly reduced the duration of IMV in preterm neonates, and both NHFOV and NIPPV resulted in a lower risk of reintubation than NCPAP. All 3 respiratory support techniques were equally safe for this patient population.

Trial Registration

ClinicalTrials.gov Identifier: NCT03181958.

Weaning of invasive ventilation in the neonatal intensive care: Towards standardising practice: A narrative review

To present a physiological algorithmic approach to weaning of invasive ventilation in the neonatal intensive care, focusing mainly on the preterm infant. Review of literature, consensus guidelines, expert commentaries and practice guidelines from individual units. Weaning of ventilation for extubation in the neonatal population must follow certain criteria but needs individualising based on disease process, timeline and physiology. Algorithms based on scenarios and modes of ventilation used might aid the clinician on the floor for decision-making process.

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..

The long-term outcomes of preterm infants receiving non-invasive high-frequency oscillatory ventilation

OBJECTIVE

To investigate the clinical outcomes of preterm infants who received non-invasive high-frequency oscillatory ventilation following extubation in a neonatal intensive care unit.

METHODS

Infants born between 25 and 34 weeks of gestation with a birth weight of <1,500 g, who were admitted into the neonatal intensive care unit of Guangxi Maternal and Child Health Hospital, Nanning, Guangxi, China, requiring mechanical ventilation on admission were randomized to the non-invasive high-frequency ventilation group, nasal intermittent positive pressure ventilation group, or nasal continuous positive airway pressure group following extubation. Their respiratory and neurodevelopmental outcomes were assessed at 12 and 24 months of corrected age.

RESULTS

Among 149 preterm infants who underwent randomization, 139 completed their treatment in the neonatal intensive care unit (45, 47, 47 in the non-invasive high-frequency ventilation group, nasal intermittent positive pressure ventilation group, or nasal continuous positive airway pressure group, respectively), 113 were assessed at 12-month corrected age, and 110 of 113 were assessed again at 24-month corrected age. There were no differences in the number of times bronchitis, pneumonia, wheezing episodes, and re-hospitalization rates appeared due to respiratory diseases among the three groups (P > 0.05); the pulmonary function tests at 12-month corrected age showed respiratory rate, tidal volume, inspiratory time/expiratory time, time to peak expiratory flow/expiratory time, volume at peak expiratory flow/expiratory volume, expiratory flow at 25, 50, and 75% tidal volume were all similar among infants from the 3 groups (P > 0.05). There were no differences in the rates of neurodevelopmental impairment among the three groups at 24-month corrected age (P > 0.05).

CONCLUSION

As post-extubation respiratory support in preterm infants, non-invasive high-frequency ventilation did not increase the rates of long-term respiratory morbidities and neurodevelopmental impairment compared with nasal intermittent positive pressure ventilation and nasal continuous positive airway pressure.

Use of NHFOV vs. NIPPV for the respiratory support of preterm newborns after extubation: A meta-analysis

OBJECTIVES

This meta-analysis evaluated and compared the efficacy and safety of noninvasive high-frequency oscillatory ventilation (NHFOV) and nasal intermittent positive-pressure ventilation (NIPPV) for preterm newborns after extubation.

METHODS

We searched the PubMed, Cochrane Library, EMBASE, Web of Science, CNKI, Wanfang and VIP databases from inception to August 28, 2022. Randomized controlled trials (RCTs) that evaluated and compared the efficacy and safety of NHFOV and NIPPV in newborns were included in the review and meta-analysis, which followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines.

RESULTS

Eight studies involving 1,603 patients were included. Compared with NIPPV, NHFOV could reduce the reintubation rates (RR = 0.68, 95% CI 0.53, 0.86, P = 0.002). Subgroup analysis showed that the significant difference was found in reintubation rates within 72 h (RR = 0.48, 95% CI 0.32, 0.73, P = 0.0005). NHFOV also could decrease the duration of non-invasive ventilation (standard mean difference (SMD) = -1.52, 95% CI -2.58, -0.45, P = 0.005). However, all included studies had a high risk of bias, and the overall quality of the evidence of the outcomes was low or very low.

CONCLUSION

In our study, compared with NIPPV, NHFOV seems to reduce the reintubation rates without increasing adverse outcomes. Nevertheless, definite recommendations cannot be made based on the quality of the published evidence.

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 Intertemporal Role of Respiratory Support in Improving Neonatal Outcomes: A Narrative Review

Defining improvements in healthcare can be challenging due to the need to assess multiple outcomes and measures. In neonates, although progress in respiratory support has been a key factor in improving survival, the same degree of improvement has not been documented in certain outcomes, such as bronchopulmonary dysplasia. By exploring the evolution of neonatal respiratory care over the last 60 years, this review highlights not only the scientific advances that occurred with the application of invasive mechanical ventilation but also the weakness of the existing knowledge. The contributing role of non-invasive ventilation and less-invasive surfactant administration methods as well as of certain pharmacological therapies is also discussed. Moreover, we analyze the cost-benefit of neonatal care-respiratory support and present future challenges and perspectives.

Nasal high-frequency jet ventilation (NHFJV) as a novel means of respiratory support in extremely low birth weight infants

OBJECTIVE

Describe our experience of successfully using nasal high-frequency jet ventilation (NHFJV) in extremely low birth weight infants with respiratory failure.

STUDY DESIGN

A retrospective review was conducted on 16 infants with birth weights <1000 g who received NHFJV from 2015 to 2019. Successful use was defined as avoiding intubation for at least 72 hours and demonstrating tolerance after being placed on NHFJV.

RESULTS

Median gestational age was 24.5 weeks (IQR 24, 25), and weight at the start of NHFJV 1090 g (IQR 905, 1250). NHFJV was used successfully in 13/16 (81%) infants with a median duration of 7 days (IQR 3, 12). Days on invasive (30 vs. 186) and noninvasive (46 vs. 81) ventilation were shorter when compared to those who failed the use of NHFJV.

CONCLUSION

This is the first reported case series for the successful use of NHFJV. Our study highlights the feasibility of a potential new mode of noninvasive respiratory support.

Transmission of Oscillatory Volumes into the Preterm Lung during Noninvasive High-Frequency Ventilation

Rationale: There is increasing evidence for a clinical benefit of noninvasive high-frequency oscillatory ventilation (nHFOV) in preterm infants. However, it is still unknown whether the generated oscillations are effectively transmitted to the alveoli.Objectives: To assess magnitude and regional distribution of oscillatory volumes (V_Osc) at the lung level.Methods: In 30 prone preterm infants enrolled in a randomized crossover trial comparing nHFOV with nasal continuous positive airway pressure, electrical impedance tomography recordings were performed. During nHFOV, the smallest amplitude to achieve visible chest wall vibration was used, and the frequency was set at 8 hertz.Measurements and Main Results: Thirty consecutive breaths during artifact-free tidal ventilation were extracted for each of the 228 electrical impedance tomography recordings. After application of corresponding frequency filters, Vt and V_Osc were calculated. There was a signal at 8 and 16 Hz during nHFOV, which was not detectable during nasal continuous positive airway pressure, corresponding to the set oscillatory frequency and its second harmonic. During nHFOV, the mean (SD) V_Osc/Vt ratio was 0.20 (0.13). Oscillations were more likely to be transmitted to the non-gravity-dependent (mean difference [95% confidence interval], 0.041 [0.025-0.058]; P < 0.001) and right-sided lung (mean difference [95% confidence interval], 0.040 [0.019-0.061]; P < 0.001) when compared with spontaneous Vt.Conclusions: In preterm infants, V_Osc during nHFOV are transmitted to the lung. Compared with the regional distribution of tidal breaths, oscillations preferentially reach the right and non-gravity-dependent lung. These data increase our understanding of the physiological processes underpinning nHFOV and may lead to further refinement of this novel technique.

Hemodynamic effects of high-frequency oscillatory ventilation in preterm neonates with respiratory distress syndrome

BACKGROUND

High-frequency oscillatory ventilation (HFOV) can have negative hemodynamic effects in neonates. We aimed to assess systemic, cerebral, and cardiac hemodynamic changes in preterm neonates with respiratory distress syndrome (RDS) on HFOV.

METHODS

This observational study was conducted from June 2017 until May 2019 on 100 preterm neonates with RDS that needed switching from conventional mechanical ventilation to HFOV. Initial and Follow up capillary blood gas, echocardiographic examination, cranial ultrasound, and Doppler study of cerebral, celiac, superior mesenteric, and renal arteries using resistive index (RI) were performed before, 24 h, and 72 h after the use of HFOV.

RESULTS

There was no statistically significant difference as regards cardiac function, heart rate, or intraventricular hemorrhage on follow up measurements. However blood pressure, left ventricular dimensions, and volumes statistically increased after HFOV. There was a statistically significant decrease in the pulmonary artery systolic pressure after the use of HFOV. After the use of HFOV, there was a statistically significant increase in the superior vena cava flow and left ventricular output while right ventricular output values initially increased then slightly decreased but still higher than the initial values. RI of cerebral, superior mesenteric, celiac, and renal arteries significantly decreased on follow up measurements which reflected increased blood flow in these arteries.

CONCLUSION

HFOV had no negative effect on the cerebral, systemic, or cardiac hemodynamics when applied at optimum MAP. Therefore, concerns about negative hemodynamic effects of HFOV should not discourage the use of HFOV when deemed clinically indicated provided the use of optimum MAP.

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 vs. Nasal Continuous Positive Airway Pressure as Therapy for Postextubation Respiratory Failure in Infants After Congenital Heart Surgery

Objective: This study aimed to evaluate the effects of nasal high-frequency oscillatory ventilation (NHFOV) vs. nasal continuous positive airway pressure (NCPAP) on postextubation respiratory failure (PRF) in infants after congenital heart surgery (CHS). Method: Eighty infants underwent postoperative invasive mechanical ventilation for more than 12 h and planned extubation. The infants were randomized to undergo either NHFOV or NCPAP after extubation. Primary outcomes were the incidence of PRF and reintubation, the average PaCO₂ level, the average oxygenation index (OI), and pulmonary recruitment in the early extubation phase. Secondary outcomes included the NCPAP/NHFOV time, length of hospital stay, treatment intolerance, signs of discomfort, pneumothorax, adverse hemodynamic effects, nasal trauma, and mortality. Results: Except for PaCO₂ within 12 after extubation (39.3 ± 5.8 vs. 43.6 ± 7.3 mmHg, p = 0.05), there was no statistically significant difference for any of the primary outcome measure (PRF, reintubation within 12 h after extubation, oxygenation index within 12 h after extubation, or lung volumes on X-ray after extubation) or secondary outcome measures (duration of non-invasive ventilation, duration of hospital stay, ventilation intolerance, signs of discomfort, pneumothorax, nasal trauma, adverse hemodynamic effects, or death prior to discharge), p > 0.1 for each comparison. Conclusion: NHFOV therapy after extubation in infants after CHS was more efficient in improving CO₂ cleaning than NCPAP therapy, but there was no difference in other outcomes (PRF, reintubation, oxygenation index, and pulmonary recruitment).

Nasal HFOV versus nasal IPPV as a post-extubation respiratory support in preterm infants-a randomised controlled trial

Early and successful extubation prevents several morbidities in preterm newborns. Several secondary non-invasive respiratory modalities exist but with their merits and demerits. Given the benefits of nasal high-frequency oscillatory ventilation (nHFOV), we tried to examine whether nHFOV could reduce reintubation rates compared to nasal intermittent positive pressure ventilation (NIPPV) during the post-extubation phase in preterm infants. Stratified randomisation based on gestational age was done for 86 mechanically ventilated preterm infants between 26 and 36⁺⁶ weeks of gestation within 2 weeks of age to receive either nHFOV or NIPPV post-extubation. The main objective was to compare extubation failure within 72 h following extubation and secondarily feed intolerance, intraventricular haemorrhage (IVH) (> grade 3), composite bronchopulmonary dysplasia (BPD)/mortality, composite duration of oxygen supplementation/ventilation support and SpO2/FiO2 ratio. No statistical difference was noted for primary outcome (RR 0.8, 95% CI: 0.23 to 2.78; p = 1.00) and secondary outcomes. However, nHFOV appeared possibly better in respect to feed tolerance rates and pCO2 washout.Conclusion: Extubation failure within 72 h in infants less than 37 weeks of gestation did not differ between the two groups. However, nHFOV seems promising in reducing enteral feeding issues and pCO2 elimination. Larger multicentre studies are required for exploring benefits of nHFOV.Trial registration: www.ctri.nic.in id CTRI/2019/07/020055, registration date July 5, 2019 What is Known: • NIPPV is superior to nCPAP as a secondary mode of respiratory support. • Synchronisation is preferred for optimum ventilation. What is New: • nHFOV, a novel non-invasive respiratory modality without need for synchronisation, appears promising as a secondary mode subject to further trials. • It seems promising in reducing enteral feeding issues and pCO2 elimination.

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.

Nasal High Frequency Oscillatory Ventilation for Respiratory Failure due to Respiratory Syncytial Virus Bronchiolitis: Case Report

The authors describe a case of acute respiratory failure due to severe bronchiolitis. During high-flow nasal cannula ventilation, the blood's high levels of hypercapnia had taken them to plan the sedation and the orotracheal intubation. However, before attempting intubation, a nasal high frequency oscillatory ventilation cycle was performed and it led to a marked improvement in the blood gas, avoiding in this way the invasive ventilation.

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.

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.

A Review on Non-invasive Respiratory Support for Management of Respiratory Distress in Extremely Preterm Infants

Majority of extremely preterm infants require positive pressure ventilatory support at the time of delivery or during the transitional period. Most of these infants present with respiratory distress (RD) and continue to require significant respiratory support in the neonatal intensive care unit (NICU). Bronchopulmonary dysplasia (BPD) remains as one of the major morbidities among survivors of the extremely preterm infants. BPD is associated with long-term adverse pulmonary and neurological outcomes. Invasive mechanical ventilation (IMV) and supplemental oxygen are two major risk factors for the development of BPD. Non-invasive ventilation (NIV) has been shown to decrease the need for IMV and reduce the risk of BPD when compared to IMV. This article reviews respiratory management with current NIV support strategies in extremely preterm infants both in delivery room as well as in the NICU and discusses the evidence to support commonly used NIV modes including nasal continuous positive airway pressure (NCPAP), nasal intermittent positive pressure ventilation (NIPPV), bi-level positive pressure (BI-PAP), high flow nasal cannula (HFNC), and newer NIV strategies currently being studied including, nasal high frequency ventilation (NHFV) and non-invasive neutrally adjusted ventilatory assist (NIV-NAVA). Randomized, clinical trials have shown that early NIPPV is superior to NCPAP to decrease the need for intubation and IMV in preterm infants with RD. It is also important to understand that selection of the device used to deliver NIPPV has a significant impact on its success. Ventilator generated NIPPV results in significantly lower rates of extubation failures when compared to Bi-PAP. Future studies should address synchronized NIPPV including NIV-NAVA and early rescue use of NHFV in the respiratory management of extremely preterm infants.

An in-line high frequency flow interrupter applied to nasal CPAP: Improved carbon dioxide clearance in a premature infant lung model

BACKGROUND

Noninvasive respiratory support continues to have high failure rates in small preterm infants. We previously demonstrated significantly improved in vitro CO₂ washout by applying oscillations to a high flow nasal cannula system.

OBJECTIVE

To develop a high frequency flow interrupter that could be applied to commonly used nasal continuous positive airway pressure (NCPAP) devices and to determine the effect of oscillations on end-tidal carbon dioxide (EtCO₂ ) levels in an infant lung model.

DESIGN/METHODS

NCPAP was applied to a premature infant lung simulator using either bubble (BCPAP) or variable-flow (VCPAP) CPAP. Supply gas was interrupted with a solenoid pinch valve. EtCO₂ was measured before and during oscillation and repeated at 4, 6, 8, 10, and 12 Hz oscillation and CPAP pressures of 4, 6, and 8 cm H ₂ O.

RESULTS

BCPAP and VCPAP EtCO₂ levels decreased with oscillation (P < .001). BCPAP EtCO₂ was significantly dependent on oscillation frequency (P < .001) with decreases of 18% to 47% and maximum effect at 10 Hz. Optimum VCPAP CO₂ clearance occurred at 6 Hz with reductions of 30% and 39% at 6 and 8 cm H₂ O CPAP respectively. BCPAP and VCPAP mean airway pressures remained unchanged transitioning from nonoscillation to oscillation. Oscillated BCPAP and VCPAP average amplitudes were 8.3 ± 0.5 and 8.4 ± 2.3 SD cm H₂ O, respectively. Power spectrum analysis of non-oscillated BCPAP showed bubbling-only dominant peaks at 10 to 12 Hz corresponding with the maximum BCPAP EtCO₂ reductions.

CONCLUSION

Application of high frequency oscillation to NCPAP improves CO₂ clearance in a premature infant lung model. This simple modification to NCPAP delivery devices may prove to be an effective enhancement of this mode of noninvasive respiratory support.

[Research advances in the methods for weaning from high-frequency oscillatory ventilation in neonates]

Neonatal respiratory failure is a serious clinical illness commonly seen in the neonatal intensive care unit (NICU). Although clinicians want to maximize noninvasive respiratory support, some low-birth-weight preterm infants may require invasive respiratory support from the beginning. As an important respiratory management technique for the treatment of respiratory failure, high-frequency oscillatory ventilation (HFOV) allows gas exchange by rapid delivery at a tidal volume lower than or equal to anatomy death volume. Continuous distending pressure was applied to achieve uniform lung expansion, reduce repeated contraction of lung tissue, and exert a protective effect on lung tissue, and so it is preferred by clinicians and has been widely used in clinical practice. However, no consensus has been reached on the methods for weaning from HFOV. This article reviews the methods for weaning from HFOV, so as to provide help for clinical practice.

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.

Mechanics of nasal mask-delivered HFOV in neonates: A physiologic study

OBJECTIVES

To clarify if nasal mask influences noninvasive high-frequency oscillatory ventilation (NHFOV) mechanics to optimize the clinical use of nasal mask-delivered NHFOV.

WORKING HYPOTHESIS

Nasal mask may affect the mechanical efficacy of NHFOV.

METHODOLOGY

We designed a physiologic study composed of an in vitro phase aiming to investigate pressure transmission and volume delivery in a bench model of nasal mask-delivered NHFOV. In a second phase, we measured the leaks in vivo in a series of neonates receiving nasal mask-delivered NHFOV or other forms of noninvasive respiratory support with same nasal masks.

RESULTS

In vitro pressure transmission is lower with nasal mask (pressure at the lung [Plung]: 2 [0.8]), than with the endotracheal tube (Plung 9.5 [1.5] cmH₂ O; P = 0.007). Same applies for volume delivery (Vol: 0.6 [0.2] vs 1.8 [0.5] mL; P = 0.0001). Increasing ventilatory boundaries slowly affects pressure and volume delivery. Ventilating the model with maximal parameters (∆P = 55 cmH₂ O; frequency = 8 Hz) we obtained a Vol 1.5 (0.2) mL. The nasal mask provides lower volume delivery and ventilation, compared with nasal prongs studied in previously published studies. Changing frequency allows a better performance than changing ∆P. In vivo leaks are approximately 30% and are similar during NHFOV or other forms of nasal mask-delivered noninvasive ventilation.

CONCLUSIONS

Nasal mask-delivered NHFOV is feasible, but it may require more aggressive ventilatory parameters to increase volume delivery and ventilation. The use of the nasal mask is associated with some leaks, but this is independent from the type of noninvasive respiratory support applied.

Continuous positive airway pressure (CPAP) vs noninvasive positive pressure ventilation (NIPPV) vs noninvasive high frequency oscillation ventilation (NHFOV) as post-extubation support in preterm neonates: protocol for an assessor-blinded, multicenter, randomized controlled trial

BACKGROUND

Various noninvasive respiratory support modalities are available in neonatal critical care in order to minimize invasive ventilation. Continuous positive airway pressure (CPAP) is the more commonly used but noninvasive positive pressure ventilation (NIPPV) seems more efficacious in the early post-extubation phase, although it is not clear if NIPPV may influence longterm outcomes. A recently introduced alternative is noninvasive high frequency oscillatory ventilation (NHFOV) which might be especially useful in babies needing high constant distending pressure. Preterm neonates may receive these respiratory supports for several weeks. Nonetheless, no data are available for the longterm use of NIPPV and NHFOV; few data exist on NHFOV and clinical outcomes, although its safety and suitability are reported in a number of preliminary short-term studies.

METHODS

We designed an assessor-blinded, multicenter, three-arms, parallel, pragmatic, randomized, controlled trial with a superiority design, investigating the use of CPAP vs NIPPV vs NHFOV during the whole stay in neonatal intensive care units in China. Since safety data will also be analyzed it may be considered a phase II/III trial. Moreover, subgroup analyses will be performed on patients according to prespecified criteria based on physiopathology traits: these subgroup analyses should be considered preliminary. At least 1440 neonates are supposed to be enrolled. The trial has been designed with the collaboration of international colleagues expert in NHFOV, who will also perform an interim analysis at the about 50% of the enrolment.

DISCUSSION

The study is applying the best trial methodology to neonatal ventilation, a field where it is often difficult to do so for practical reasons. Nonetheless, ours is also a physiology-driven trial, since interventions are applied based on physiological perspective, in order to use ventilatory techniques at their best. The pragmatic design will increase generalizability of our results but subgroup analyses according to predefined physiopathological criteria are also previewed trying to have some advantages of an explanatory design. Since not all clinicians are well versed in all respiratory techniques, the training is pivotal. We intend to apply particular care to train the participating units: a specific 3-month period and several means have been dedicated to this end.

TRIAL REGISTRATION

NCT03181958 (registered on June 9, 2017).

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.

Effect of high frequency oscillatory high flow nasal cannula on carbon dioxide clearance in a premature infant lung model: A bench study

OBJECTIVE

This study compared CO₂ clearance in a premature infant lung model connected to a high flow nasal cannula (HFNC) system supplied with oscillatory versus non-oscillatory flow.

DESIGN/METHODS

The lung model was set to compliance 1.0 mL/cmH₂ O, RR 60 breaths/min, and 6 mL tidal volume. A 100% CO₂ was injected at a constant 15 mL/min. To create oscillation, HFNC flow was interrupted at rates of 4-6-8 and 10 Hz. equilibrated end-tidal CO₂ (ETCO₂ ) was recorded with and without oscillation at set flows of 2-8 L/min and repeated for each oscillation frequency.

RESULTS

Overall ETCO₂ decreased significantly (P < 0.001) during both non-oscillatory and oscillatory HFNC as set flow increased from 2 to 8 L/min by 26.3% and 60.8%, respectively. Oscillatory ETCO₂ levels decreased linearly compared to non-oscillatory HFNC with negligible difference at 2 L/min and a 48.4% difference at 8 L/min (P < 0.001). There were no differences in ETCO₂ levels between oscillation frequencies at any flow except at 6 Hz for which ETCO₂ was significantly lower (P < 0.01) than at 4, 8, and 10 Hz for 5-8 L/min HFNC flows. Amplitude of volume oscillations increased with increasing flow from 0.5 mL at 2 L/min to 4.0 mL at 8 L/min (P < 0.001), and decreased with increasing oscillation frequency.

CONCLUSION

Oscillatory HFNC as compared to non-oscillatory was associated with significantly improved CO₂ clearance in this premature infant lung model. This simple modification of the HFNC system may prove to be a useful enhancement to this mode of non-invasive respiratory support for preterm infants at high risk for respiratory failure.

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.

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.

Cell Count Analysis from Nonbronchoscopic Bronchoalveolar Lavage in Preterm Infants

OBJECTIVES

To establish the reference values, diagnostic accuracy, and effect of various factors on cell count in intubated preterm neonates subjected to nonbronchoscopic bronchoalveolar lavage.

STUDY DESIGN

This prospective, cross-sectional, blinded study included preterm neonates ventilated for any reason who underwent nonbronchoscopic bronchoalveolar lavage if they had not previously received postnatal antibiotics or steroids. Lavage was performed before surfactant replacement, if any. A gentle ventilation policy was applied. Pneumonia was diagnosed using clinical criteria, without considering cell count. Investigators performing cell counts were blinded to the clinical data.

RESULTS

There were 276 neonates enrolled; 36 had congenital or ventilator-associated pneumonia. In the 240 noninfected babies, median neutrophil count increased significantly after the first 2 days of ventilation (day 1, 2 cells per field [IQR, 0.0-9.5 cells per field]; day 2, 2 cells per field [IQR, 0-15 cells per field]; day 3, 20 cells per field [IQR, 2-99 cells per field]; day 4, 15 cells per field [IQR, 2-96 cells per field]; P < .0001). No significant difference was seen over time in infected babies. Multivariate analysis indicated pneumonia (standardized β = 0.134; P = .033) and the time spent under mechanical ventilation before nonbronchoscopic bronchoalveolar lavage as factors significantly influencing neutrophil count (standardized β = 0.143; P = .027). Neutrophil count was correlated with the duration of ventilation (rho = 0.28; P <.001). Neutrophil counts were higher in infected (24 cells/field [IQR, 5-78] cells/field) than in noninfected babies (4 cells/field [IQR, 1-24 cells/field]; P <.001) and had an moderate reliability for pneumonia within the first 2 days of ventilation (area under the curve, 0.745; (95% CI, 0.672-0.810; P = .002).

CONCLUSIONS

We provide reference values for airway neutrophil counts in ventilated preterm neonates. Bronchoalveolar lavage neutrophils significantly increase after 2 days of ventilation. Neutrophil count has moderate accuracy to diagnose pneumonia, but only within the first 2 days of ventilation.

Non-invasive high-frequency oscillatory ventilation in preterm infants: a randomised controlled cross-over trial

OBJECTIVE

Non-invasive high-frequency oscillatory ventilation (nHFOV) has recently been described as a novel mode of respiratory support for premature infants. This study was designed to determine whether nHFOV decreases CO₂ partial pressure (pCO₂) in premature infants more effectively than non-invasive continuous positive airway pressure (nCPAP).

DESIGN

Non-blinded prospective randomised controlled cross-over study.

SETTING

University Medical Center tertiary neonatal intensive care unit.

PATIENTS

26 premature infants of 27±2 weeks of gestational age after extubation or non-invasive surfactant treatment.

INTERVENTIONS

Infants were treated with 4 hours of nHFOV and 4 hours of nCPAP in a cross-over design. The sequence of the ventilation mode was randomly allocated.

MAIN OUTCOME MEASURES

The primary outcome measure was pCO₂ of arterial or arterialised blood 4 hours after commencing the respective mode of respiratory support. Secondary outcome criteria included events of apnoea and bradycardia, respiratory rate, heart rate, pain and/or discomfort, mean airway pressure, fraction of inspired oxygen and failure of non-invasive respiratory support.

RESULTS

pCO₂ after 4 hours of nHFOV was similar compared with 4 hours of nCPAP (p=0.33). pCO₂ was 54.8 (14.6) vs 52.7 (9.3) mm Hg mean (SD) for the nHFOV-nCPAP period (n=13) and 49.0 (8.1) vs 47.7 (9.5) mm Hg for the nCPAP-nHFOV period (n=13). There was no difference in any of the secondary outcome measures. nHFOV was terminated prematurely in five cases for predefined failure criteria (p=0.051).

CONCLUSIONS

We could not demonstrate an increased carbon dioxide clearance applying nHFOV compared with nCPAP in this cohort of preterm infants.

TRIAL REGISTRATION NUMBER

DRKS00007171, results.