High-Frequency Jet Ventilation in Neonatal and Pediatric Subjects: A Narrative Review

Neonatal high frequency ventilation: Current trends and future directions

High frequency ventilation (HFV) in neonates has been in use for over forty years. Some early HFV ventilators are no longer available, but high frequency oscillatory ventilation (HFOV) and jet ventilators (HFJV) continue to be commonly employed. Advanced HFOV models available outside of the United States are much quieter and easier to use, and are available as options on many conventional ventilators, providing important improvements such as tidal volume measurement and targeting. HFJV excels in treating air leak and non-homogenous lung disease and is often used for other diseases as well. High frequency non-invasive ventilation (hfNIV) is a novel application of HFV that remains under investigation. Similar to bubble CPAP, hfNIV has been applied with a variety of high-frequency ventilators. Efficacy and safety of hfNIV with any device have not yet been established. This article describes the current approaches to these HFV therapies and stresses the importance of understanding how each device works and what disease processes may respond best to the technology employed.

High-Frequency Positive Pressure Ventilation as Primary Rescue Strategy for Patients with Congenital Diaphragmatic Hernia: A Comparison to High-Frequency Oscillatory Ventilation

OBJECTIVE

The aim of this article was to evaluate high-frequency positive pressure ventilation (HFPPV) compared with high-frequency oscillatory ventilation (HFOV) as a rescue ventilation strategy for patients with congenital diaphragmatic hernia (CDH). HFPPV is a pressure-controlled conventional ventilation method utilizing high respiratory rate and low positive end-expiratory pressure.

STUDY DESIGN

Seventy-seven patients diagnosed with CDH from January 2005 to September 2019 who were treated with stepwise progression from HFPPV to HFOV versus only HFOV were included. Fisher's exact test and the Kruskal-Wallis test were used to compare outcomes.

RESULTS

Patients treated with HFPPV + HFOV had higher survival to discharge (80 vs. 50%, p = 0.007) and to surgical intervention (95.6 vs. 68.8%, p = 0.003), with average age at repair 2 days earlier (p = 0.004). Need for extracorporeal membrane oxygenation (p = 0.490), inhaled nitric oxide (p = 0.585), supplemental oxygen (p = 0.341), and pulmonary hypertension medications (p = 0.381) were similar.

CONCLUSION

In CDH patients who fail respiratory support with conventional ventilation, HFPPV may be used as an intermediary mode of rescue ventilation prior to HFOV without adverse effects.

KEY POINTS

· HFPPV may be used as an intermediary mode of rescue ventilation prior to HFOV without adverse effect.. · HFPPV is more widely available and can mitigate the limitations faced when using HFOV.. · HFPPV allows for intra- or interhospital transfer of neonates with CDH..

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

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

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.

Neonatal abdominal support to address CPAP belly: Two cases report and literature review

Gaseous distension of the abdomen from the use of continuous positive airway pressure (CPAP) in the preterm population is of increasing concern for its unintended consequences. Methods to treat and prevent CPAP belly deserve further investigation. An intervention to provide abdominal support to address CPAP belly is presented in these case studies.

2021 Year in Review: Pediatric Mechanical Ventilation

Mechanical ventilation is commonly used in the pediatric intensive care unit. This paper reviews studies of pediatric mechanical ventilation published in 2021. Topics include physiology, ventilator modes, alarms, disease states, airway suctioning, ventilator liberation, prolonged ventilation, and others.

Mechanical Ventilation and Respiratory Support in the Pediatric Intensive Care Unit

Children admitted to the pediatric intensive care unit often require respiratory support for the treatment of respiratory distress and failure. Respiratory support comprises both noninvasive modalities (ie, heated humidified high-flow nasal cannula, continuous positive airway pressure, bilevel positive airway pressure, negative pressure ventilation) and invasive mechanical ventilation. In this article, we review the various essential elements and considerations involved in the planning and application of respiratory support in the treatment of the critically ill children.

The Physiological Basis of High-Frequency Oscillatory Ventilation and Current Evidence in Adults and Children: A Narrative Review

High-frequency oscillatory ventilation (HFOV) is a type of invasive mechanical ventilation that employs supra-physiologic respiratory rates and low tidal volumes (V_T) that approximate the anatomic deadspace. During HFOV, mean airway pressure is set and gas is then displaced towards and away from the patient through a piston. Carbon dioxide (CO₂) is cleared based on the power (amplitude) setting and frequency, with lower frequencies resulting in higher V_T and CO₂ clearance. Airway pressure amplitude is significantly attenuated throughout the respiratory system and mechanical strain and stress on the alveoli are theoretically minimized. HFOV has been purported as a form of lung protective ventilation that minimizes volutrauma, atelectrauma, and biotrauma. Following two large randomized controlled trials showing no benefit and harm, respectively, HFOV has largely been abandoned in adults with ARDS. A multi-center clinical trial in children is ongoing. This article aims to review the physiologic rationale for the use of HFOV in patients with acute respiratory failure, summarize relevant bench and animal models, and discuss the potential use of HFOV as a primary and rescue mode in adults and children with severe respiratory failure.

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.

Update on ventilation management in the Pediatric Intensive Care Unit

Studies have shown that up to 63% of pediatric intensive care unit patients admitted with acute respiratory or cardiorespiratory illness require mechanical ventilation. Mechanical ventilator support can be divided into three phases: initiation, escalation, and resolution. Noninvasive ventilation is typical during the initiation phase in the management of acute pediatric respiratory failure. The major advancements in the use of noninvasive ventilation involve the emergence of high-flow nasal cannula and how widespread the use of high-flow nasal cannula has become in pediatric critical care practice. When high-flow nasal cannula fails, escalation to continuous positive airway pressure or bi-level positive airway pressure is the next step in respiratory care progression. Careful clinical assessment is necessary to avoid delayed escalation between forms of noninvasive support or escalation to intubation and invasive mechanical ventilation. Advancements in conventional mechanical ventilation are centered on optimizing ventilator settings and customizing monitoring with the overarching goal to reduce complications of mechanical ventilation, such as ventilator-induced lung injury. New mechanical ventilator strategies integrating esophageal pressure monitoring, volumetric capnography, and neurally adjusted ventilator assist help to optimize conventional ventilator support. Nonconventional modes of ventilation in the intensive care unit are high-frequency modes and airway pressure release ventilation. Extracorporeal pulmonary support via extracorporeal membrane oxygenation or paracorporeal lung assist devices provides rescue options when conventional and nonconventional methods fail. During resolution of a course of mechanical ventilator support, reliable weaning strategies and extubation readiness testing are lacking in pediatric critical care. Further, timing of tracheostomy, risk reduction in ventilator-induced lung injury, and decreased sedation requirements in pediatric patients requiring mechanical ventilation in the pediatric intensive care unit are areas of ongoing research.

High-Frequency Jet Ventilation in Infants With Congenital Heart Disease

BACKGROUND

High-frequency jet ventilation (HFJV) is primarily used in neonates but may also have a role in the treatment of infants with congenital heart disease and severe respiratory failure. We hypothesized that HFJV would result in improved gas exchange in these infants.

METHODS

We retrospectively reviewed the records of all pediatric patients with complex congenital heart disease treated HFJV in our pediatric cardiac ICU between 2014 and 2018. Patients in whom HFJV was started while on extracorporeal membrane oxygenation (ECMO) were excluded. We extracted data on demographics, pulmonary mechanics, gas exchange, the subsequent need for ECMO, use of inhaled nitric oxide, and outcomes.

RESULTS

We included 27 subjects (median [interquartile range {IQR}] weight 4.4 [3.3-5.4] kg; median [IQR] age 2.5 [0.3-5.4] months), 22 (82%) of whom had cyanotic heart disease. Thirteen subjects (48%) survived and 6 (22%) required ECMO. HFJV was started after a median (IQR) of 8.4 (2.1-26.3) d of conventional mechanical ventilation. The subjects spent a median (IQR) of 1.2 (0.5-2.8) d on HFJV. The median (IQR) pre-HFJV blood gas results (n = 25) were pH 7.22 (7.17-7.31), [Formula: see text] 69 (51-77) mm Hg, and [Formula: see text] 51 (41-76) mm Hg. Median (IQR) initial HFJV settings were peak inspiratory pressure of 45 (36-50) cm H₂O, breathing frequency of 360 (360-380) breaths/min, and inspiratory time of 0.02 (0.02-0.03) s. Compared with conventional mechanical ventilation, at 4-6 h after HFJV initiation, there were significant improvements in the median pH (7.22 vs 7.34; P = .001) and [Formula: see text] (69 vs 50 mm Hg; P = .001), respectively, but no difference in median [Formula: see text] (51 vs 53 mm Hg; P = .97).

CONCLUSIONS

HFJV was associated with a decrease in [Formula: see text] and an increase in pH in infants with congenital heart disease who remained on HFJV 4 to 6 h after initiation.