An observational, prospective, multicenter study on rescue high-frequency oscillatory ventilation in neonates failing with conventional ventilation

Neonatal high-frequency oscillatory ventilation: where are we now?

High-frequency oscillatory ventilation (HFOV) is an established mode of respiratory support in the neonatal intensive care unit. Large clinical trial data is based on first intention use in preterm infants with acute respiratory distress syndrome. Clinical practice has evolved from this narrow population. HFOV is most often reserved for term and preterm infants with severe, and often complex, respiratory failure not responding to conventional modalities of respiratory support. Thus, optimal, and safe, application of HFOV requires the clinician to adapt mean airway pressure, frequency, inspiratory:expiratory ratio and tidal volume to individual patient needs based on pathophysiology, lung volume state and infant size. This narrative review summarises the status of HFOV in neonatal intensive care units today, the lessons that can be learnt from the past, how to apply HFOV in different neonatal populations and conditions and highlights potential new advances. Specifically, we provide guidance on how to apply an open lung approach to mean airway pressure, selecting the correct frequency and use of volume-targeted HFOV.

Association between Serum Lactate and Morbidity and Mortality in Neonates: A Systematic Review and Meta-Analysis

OBJECTIVE

Lactate is a marker of hypoperfusion in critically ill patients. Whether lactate is useful for identifying and stratifying neonates with a higher risk of adverse outcomes remains unknown. This study aimed to investigate the association between lactate and morbidity and mortality in neonates.

METHODS

A meta-analysis was performed to determine the association between blood lactate levels and outcomes in neonates. Ovid MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov were searched from inception to 1 May 2021. A total of 49 observational studies and 14 data accuracy test studies were included. The risk of bias was assessed using the Newcastle-Ottawa Scale for observational studies and the QUADAS-2 tool for data accuracy test studies. The primary outcome was mortality, while the secondary outcomes included acute kidney injury, necessity for renal replacement therapy, neurological outcomes, respiratory morbidities, hemodynamic instability, and retinopathy of prematurity.

RESULTS

Of the 3184 articles screened, 63 studies fulfilled all eligibility criteria, comprising 46,069 neonates. Higher lactate levels are associated with mortality (standard mean difference, -1.09 [95% CI, -1.46 to -0.73]). Using the estimated sensitivity (0.769) and specificity (0.791) and assuming a prevalence of 15% for adverse outcomes (median of prevalence among studies) in a hypothetical cohort of 10,000 neonates, assessing the lactate level alone would miss 346 (3.46%) cases (false negative) and wrongly diagnose 1776 (17.76%) cases (false positive).

CONCLUSIONS

Higher lactate levels are associated with a greater risk of mortality and morbidities in neonates. However, our results do not support the use of lactate as a screening test to identify adverse outcomes in newborns. Research efforts should focus on analyzing serial lactate measurements, rather than a single measurement.

High frequency jet ventilation for congenital diaphragmatic hernia

BACKGROUND

The optimal role of high frequency jet ventilation (HFJV) in lung protective stabilization of congenital diaphragmatic hernia (CDH) remains uncertain. We aimed to describe our center's experience with HFJV as both a rescue (following failed stabilization with CMV) and primary ventilation mode in the management of CDH.

METHODS

Liveborn CDH patients treated from 2013 to 2021 in a single institution were reviewed. We compared 3 groups based on their primary and last ventilation mode prior to surgery: CMV (Group 1); HFJV (Group 2); and CMV/HFJV (Group 3). Outcomes included a composite primary outcome (≥1 of mortality, need for ECMO or need for supplemental O2 at discharge), total invasive ventilation days and development of pneumothorax. A descriptive analysis including univariate group comparisons was performed. Multivariate logistic regression models investigating the relationship between mode of ventilation and the primary outcome adjusted by potentially confounding covariates were constructed.

RESULTS

56 patients (32 Group 1, 18 Group 2, 6 Group 3) were analyzed. Group 2 and 3 patients had more severe disease based on liver position, SNAP-II score, pulmonary hypertension severity, need for inotropic support, CDHSG defect size and need for patch repair. There were no group differences in survival, need for ECMO, or pneumothorax occurrence, although infants receiving HFJV required longer invasive ventilation and had a greater need for O2 at discharge. Multivariate logistic regression revealed no associations between mode of ventilation and outcome.

CONCLUSIONS

HFJV appears effective, both for CMV rescue and as a primary ventilation strategy in high risk CDH.

LEVEL OF EVIDENCE

Level IV.

The effect of high-frequency oscillatory ventilator combined with pulmonary surfactant in the treatment of neonatal respiratory distress syndrome

OBJECTIVE

To investigate the efficacy of high-frequency oscillatory ventilation (HFOV) combined with pulmonary surfactant (PS) in the treatment of neonatal respiratory distress syndrome (NRDS).

METHODS

This study is a retrospective clinical study. Seventy-two NRDS neonates were selected as the subjects from November 2019 to November 2020, and divided into observation group (40 cases, HFOV treatment) and control group (32 cases, conventional mechanical ventilation treatment). All cases were treated with PS and comprehensive treatment. The therapeutic effect, arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2), Percentage of inhaled oxygen concentration (FiO2), mean arterialpressure, oxygenation index (OI), and complications were compared in the 2 groups.

RESULTS

The total effective rate of the observation group was 90.0%, significantly higher than that of the control group. After treatment, the observation group has higher PaO2 levels and lower levels of PaCO2, mean arterial pressure, FiO2, and OI than the control group. There was no significant difference in the incidence of complications between the 2 groups.

CONCLUSION

HFOV combined with PS has a significant effect on NRDS, which can improve the arterial blood gas index without increasing the incidence of complications.

Safety use of high frequency oscillatory ventilation in transport of newborn infants affected by severe respiratory failure: preliminary data in central Tuscany

Background

Neonatal Emergency Transport Services play a fundamental role in neonatal care. Stabilization before transport of newborns suffering from severe respiratory failure is often a challenging problem and some critically ill infants may benefit from High Frequency Oscillatory Ventilation (HFOV) as rescue treatment. In these cases, transition to conventional ventilation for transport may cause a deterioration in clinical conditions. HFOV during neonatal transport has been only exceptionally used, due to technical difficulties. Since May 2018, a new neonatal transport unit is available at the Neonatal Protected Transport Service of the Meyer University Hospital in Florence, equipped with a pulmonary ventilator capable of delivering HFOV. Therefore, we conducted an analysis on patients transferred in HFOV to Neonatal Intensive Care Unit (NICU), in order to evaluate the safety and feasibility of its use during neonatal transport.

Methods

A retrospective analysis was performed reviewing medical records of the neonates transported by Meyer Children Hospital’s Neonatal Transport Service between May 2018 and December 2020, and newborns treated with HFOV during ground neonatal transport were identified. Safety was assessed by the comparison of vital signs, hemogas-analysis values and pulmonary ventilator parameters, at the time of departure and upon arrival in NICU. The dose of inotropes, the main respiratory complications (air leak, dislocation or obstruction of the endotracheal tube, loss of chest vibrations) and the number of deaths and transfer failures were recorded.

Results

Out of the approximate 400 newborns transported during the analysis period, 9 were transported in HFOV. We did not find any statistically significant difference in vital parameters, hemogas-analytical values and pulmonary ventilator settings recorded before and after neonatal transport of the nine patients’ parameters (p > 0,05). No patient required additional inotropes during transport. No transport-related deaths or significant complications occurred during transport.

Conclusions

The interest of our report is in the possibility of using HFOV during inter-hospital neonatal transfer. As far as our experience has shown, HFOV appears to be safe for the transportation of newborns with severe respiratory failure. Nevertheless, further larger, prospective and multicentre studies are needed to better evaluate the safety and efficacy of HFOV during neonatal transport.

Definitive Closure of the Patent Ductus Arteriosus in Preterm Infants and Subsequent Short-Term Respiratory Outcomes

A persistent patent ductus arteriosus (PDA) can have significant clinical consequences in preterm infants, depending on the degree of left-to-right shunting, its impact on cardiac performance, and associated perinatal risk factors that can mitigate or exacerbate the shunt. Although the best management strategy remains contentious, PDAs that have contraindications to, or have failed medical management have historically undergone surgical ligation. Recently smaller occluder devices and delivery systems have allowed for minimally invasive closure in the catheterization laboratory even in extremely premature infants. The present review summarizes the pathophysiologic manifestations, treatment options and management of hemodynamically significant PDA in preterm infants. Additionally, we review the available literature surrounding the respiratory support and outcomes of preterm infants following definitive PDA closure.

Mechanical Ventilation in Pediatric and Neonatal Patients

Pediatric acute respiratory distress syndrome (PARDS) remains a significant cause of morbidity and mortality, with mortality rates as high as 50% in children with severe PARDS. Despite this, pediatric lung injury and mechanical ventilation has been poorly studied, with the majority of investigations being observational or retrospective and with only a few randomized controlled trials to guide intensivists. The most recent and universally accepted guidelines for pediatric lung injury are based on consensus opinion rather than objective data. Therefore, most neonatal and pediatric mechanical ventilation practices have been arbitrarily adapted from adult protocols, neglecting the differences in lung pathophysiology, response to injury, and co-morbidities among the three groups. Low tidal volume ventilation has been generally accepted for pediatric patients, even in the absence of supporting evidence. No target tidal volume range has consistently been associated with outcomes, and compliance with delivering specific tidal volume ranges has been poor. Similarly, optimal PEEP has not been well-studied, with a general acceptance of higher levels of F_iO₂ and less aggressive PEEP titration as compared with adults. Other modes of ventilation including airway pressure release ventilation and high frequency ventilation have not been studied in a systematic fashion and there is too little evidence to recommend supporting or refraining from their use. There have been no consistent outcomes among studies in determining optimal modes or methods of setting them. In this review, the studies performed to date on mechanical ventilation strategies in neonatal and pediatric populations will be analyzed. There may not be a single optimal mechanical ventilation approach, where the best method may simply be one that allows for a personalized approach with settings adapted to the individual patient and disease pathophysiology. The challenges and barriers to conducting well-powered and robust multi-institutional studies will also be addressed, as well as reconsidering outcome measures and study design.

Intensivtransport Neugeborener mit respiratorischem Versagen

Hintergrund und Ziel der Studie

Der Transport von Früh und Neugeborenen mit respiratorischem Versagen ist mit einem hohen Transportrisiko assoziiert und stellt höchste Anforderungen an medizinisches Personal und technische Ausrüstung. Eine kontinuierliche Überprüfung der Qualität ist daher unumgänglich. Ziel dieser monozentrischen retrospektiven Analyse ist es, die Mortalität transportierter Neugeborener mit respiratorischem Versagen mithilfe eines Outcomescores, Transport Risk index of Physiologic Stability, Version II, (TRIPS-II-Score) und im Vergleich zu bereits publizierter Literatur zu analysieren.

Methodik

Es wurden 79 Intensivtransporte von Früh- und Neugeborenen mit hochgradigem respiratorischem Versagen retrospektiv analysiert. Zur Einschätzung des Transportrisikos und der Transportqualität wurde der TRIPS-II-Score erhoben und mit der Literatur verglichen.

Ergebnisse

Insgesamt wurden 77 Patienten luft- (n = 56, 73 %) oder bodengebunden (n = 21, 27 %) transportiert. Zwei Patienten verstarben vor dem Transport. Kein Patient verstarb während des Transports. Alle Patienten mussten invasiv beatmet werden, davon 22 (29 %) mit Hochfrequenzoszillation (HFOV) und 55 (71 %) erhielten inhalatives Stickoxid (iNO). Der mittlere Oxygenierungsindex (OI) betrug 33 [4-100, min.-max.] Insgesamt mussten 24 Patienten (31 %) nach Aufnahme einer ECMO-Therapie unterzogen werden. Insgesamt verstarben 20 (26 %) Neugeborene, 7 davon in der ECMO-Therapie-Gruppe.

Schlussfolgerung

Transporte von Neugeborenen mit schwerem Lungenversagen können durch den Einsatz eines spezialisierten Teams mit Sonderequipment meist komplikationslos durchgeführt werden. Die scheinbar sehr hohe Mortalität ist mit Daten der internationalen Literatur vergleichbar.

Therapeutic effects and outcomes of rescue high-frequency oscillatory ventilation for premature infants with severe refractory respiratory failure

Despite wide application of high frequency oscillatory ventilation (HFOV) in neonates with respiratory distress, little has been reported about its rescue use in preterm infants. We aimed to evaluate the therapeutic effects of HFOV in preterm neonates with refractory respiratory failure and investigate the independent risk factors of in-hospital mortality. We retrospectively analyzed data collected prospectively (January 2011–December 2018) in four neonatal intensive care units of two tertiary-level medical centers in Taiwan. All premature infants (gestational age 24–34 weeks) receiving HFOV as rescue therapy for refractory respiratory failure were included. A total of 668 preterm neonates with refractory respiratory failure were enrolled. The median (IQR) gestational age and birth weight were 27.3 (25.3–31.0) weeks and 915.0 (710.0–1380.0) g, respectively. Pre-HFOV use of cardiac inotropic agents and inhaled nitric oxide were 70.5% and 23.4%, respectively. The oxygenation index (OI), FiO₂, and AaDO₂ were markedly increased after HFOV initiation (all p < 0.001), and can be decreased within 24–48 h (all p < 0.001) after use of HFOV. 375 (56.1%) patients had a good response to HFOV within 3 days. The final in-hospital mortality rate was 34.7%. No association was found between specific primary pulmonary disease and survival in multivariate analysis. We found preterm neonates with gestational age < 28 weeks, occurrences of sepsis, severe hypotension, multiple organ dysfunctions, initial higher severity of respiratory failure and response to HFOV within the first 72 h were independently associated with final in-hospital mortality. The mortality rate of preterm neonates with severe respiratory failure remains high after rescue HFOV treatment. Aggressive therapeutic interventions to treat sepsis and prevent organ dysfunctions are the suggested strategies to optimize outcomes.

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.