Neurally adjusted ventilatory assist in weaning of neonates affected by congenital diaphragmatic hernia

Case Report: Neurally adjusted ventilatory assist as an effective rescue treatment for pulmonary interstitial emphysema in extremely low birth weight infants

Pulmonary interstitial emphysema (PIE) is a complication observed in extremely low birth weight (ELBW) infants on mechanical ventilation. Despite various proposed therapeutic interventions, the success rates have shown inconsistency. Neurally adjusted ventilatory assist (NAVA) stands out as a novel respiratory support mode, offering lower pressure and tidal volume in comparison to conventional ventilation methods. In this case report, we present five ELBW infants with refractory PIE who were transitioned to NAVA ventilation. Following the switch to NAVA, all cases of PIE gradually resolved. In contrast to traditional modes, NAVA provided respiratory support with significantly lower fraction of inspired oxygen, reduced peak inspiratory pressure, diminished mean airway pressure, and decreased tidal volume within 7 days of NAVA utilization (p = 0.042, 0.043, 0.043, and 0.042, respectively). Consequently, we propose that NAVA could serve as a valuable rescue treatment for ELBW infants with PIE.

Study protocol for a randomised cross-over trial of Neurally adjusted ventilatory Assist for Neonates with Congenital diaphragmatic hernias: the NAN-C study

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is a mode of mechanical ventilation that delivers oxygen pressures in proportion to electrical signals of the diaphragm. The proportional assistance can be adjusted by the clinician to reduce the patient's work of breathing. Several case series of infants with congenital diaphragmatic hernias (CDH) have shown that NAVA may reduce oxygenation index and mean airway pressures. To date, no clinical trial has compared NAVA to standard methods of mechanical ventilation for babies with CDH.

METHODS

The aim of this dual-centre randomised cross-over trial is to compare post-operative NAVA with assist control ventilation (ACV) for infants with CDH. If eligible, infants will be enrolled for a ventilatory support tolerance trial (VSTT) to assess their suitability for randomisation. If clinically stable during the VSTT, infants will be randomised to receive either NAVA or ACV first in a 1:1 ratio for a 4-h period. The oxygenation index, respiratory severity score and cumulative sedative medication use will be measured.

DISCUSSION

Retrospective studies comparing NAVA to ACV in neonates with congenital diaphragmatic hernia have shown the ventilatory mode may improve respiratory parameters and benefit neonates. To our knowledge, this is the first prospective cross-over trial comparing NAVA to ACV.

TRIAL REGISTRATION

NAN-C was prospectively registered on ClinicalTrials.gov NCT05839340  Registered on May 2023.

Diaphragmatic electromyography in infants: an overview of possible clinical applications

Preterm infants often experience breathing instability and a hampered lung function. Therefore, these infants receive cardiorespiratory monitoring and respiratory support. However, the current respiratory monitoring technique may be unreliable for especially obstructive apnea detection and classification and it does not provide insight in breathing effort. The latter makes the selection of the adequate mode and level of respiratory support difficult. Electromyography of the diaphragm (dEMG) has the potential of monitoring heart rate (HR) and respiratory rate (RR), and it provides additional information on breathing effort. This review summarizes the available evidence on the clinical potential of dEMG to provide cardiorespiratory monitoring, to synchronize patient-ventilator interaction, and to optimize the mode and level of respiratory support in the individual newborn infant. We also try to identify gaps in knowledge and future developments needed to ensure widespread implementation in clinical practice. IMPACT: Preterm infants require cardiorespiratory monitoring and respiratory support due to breathing instability and a hampered lung function. The current respiratory monitoring technique may provide unreliable measurements and does not provide insight in breathing effort, which makes the selection of the optimal respiratory support settings difficult. Measuring diaphragm activity could improve cardiorespiratory monitoring by providing insight in breathing effort and could potentially have an important role in individualizing respiratory support in newborn infants.

Respiratory physiology during NAVA ventilation in neonates born with a congenital diaphragmatic hernia: The "NAVA-diaph" pilot study

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is a ventilatory mode that delivers synchronized ventilation, proportional to the electrical activity of the diaphragm (EAdi). Although it has been proposed in infants with a congenital diaphragmatic hernia (CDH), the diaphragmatic defect and the surgical repair could alter the physiology of the diaphragm.

AIM

To evaluate, in a pilot study, the relationship between the respiratory drive (EAdi) and the respiratory effort in neonates with CDH during the postsurgical period under either NAVA ventilation or conventional ventilation (CV).

METHODS

This prospective physiological study included eight neonates admitted to a neonatal intensive care unit with a diagnosis of CDH. EAdi, esophageal, gastric, and transdiaphragmatic pressure, as well as clinical parameters, were recorded during NAVA and CV (synchronized intermittent mandatory pressure ventilation) in the postsurgical period.

RESULTS

EAdi was detectable and there was a correlation between the ΔEAdi (maximal - minimal values) and the transdiaphragmatic pressure (r = 0.26, 95% confidence interval [CI] [0.222; 0.299]). There was no significant difference in terms of clinical or physiological parameters during NAVA compared to CV, including work of breathing.

CONCLUSION

Respiratory drive and effort were correlated in infants with CDH and therefore NAVA is a suitable proportional mode in this population. EAdi can also be used to monitor the diaphragm for individualized support.

Variability for Age at Successful Extubation in Infants with Congenital Diaphragmatic Hernia

OBJECTIVE

The objective of this study was to characterize clinical factors associated with successful extubation in infants with congenital diaphragmatic hernia.

STUDY DESIGN

Using the Children's Hospitals Neonatal Database, we identified infants with congenital diaphragmatic hernia from 2017 to 2020 at 32 centers. The main outcome was age in days at the time of successful extubation, defined as the patient remaining extubated for 7 consecutive days. Unadjusted Kaplan-Meier and multivariable Cox proportional hazards ratio equations were used to estimate associations between clinical factors and the main outcome. Observations occurred through 180 days after birth.

RESULTS

There were 840 eligible neonates with a median gestational age of 38 weeks and birth weight of 3.0 kg. Among survivors (n = 693), the median age at successful extubation was 15 days (interquartile range [IQR]: 8-29 days, 95th percentile: 71 days). For nonsurvivors (n = 147), the median age at death was 21 days (IQR: 11-39 days, 95th percentile: 110 days). Center (adjusted hazards ratio: 0.22-15, P < .01), low birth weight, intrathoracic liver position, congenital heart disease, lower 5-minute Apgar score, lower pH upon admission to Children's Hospitals Neonatal Database center, and use of extracorporeal support were independently associated with older age at successful extubation. Tracheostomy was associated with multiple failed extubations.

CONCLUSION

Our findings suggest that infants who have not successfully extubated by about 3 months of age may be candidates for tracheostomy with chronic mechanical ventilation or palliation. The variability of timing of successful extubation among our centers supports the development of practice guidelines after validating clinical criteria.

Ultrasonographic assessment of diaphragmatic function in preterm infants on non-invasive neurally adjusted ventilatory assist (NIV-NAVA) compared to nasal intermittent positive-pressure ventilation (NIPPV): a prospective observational study

NIV-NAVA mode for respiratory support in preterm infants is not well-studied. This study aimed to describe the diaphragmatic function, diaphragmatic excursion (DE), and thickness fraction (DTF), in preterm infants < 30 weeks' gestation supported by NIV-NAVA compared to NIPPV using bedside ultrasonography. In this consecutive prospective study, DE, diaphragmatic thickness at end of expiration (DT_exp), end of inspiration (DT_ins), and DTF were assessed using bedside ultrasound. Lung aeration evaluation using lung ultrasound score (LUS) was performed for the two groups. Diaphragmatic measurements and LUS were compared for the 2 groups (NIV-NAVA group versus NIPPV group). Statistical analyses were conducted using the SPSS software version 22. Out of 70 infants evaluated, 40 were enrolled. Twenty infants were on NIV-NAVA and 20 infants on NIPPV with a mean [SD] study age of 25.7 [0.9] weeks and 25.1 [1.4] weeks respectively (p = 0.15). Baseline characteristics and respiratory parameters at the time of the scan showed no significant difference between groups. DE was significantly higher in NIV-NAVA with a mean SD of 4.7 (1.5) mm versus 3.5 (0.9) mm in NIPPV, p = 0.007. Additionally, the mean (SD) of DTF for the NIV-NAVA group was 81.6 (30) % vs 78.2 (27) % for the NIPPV group [p = 0.71]. Both groups showed relatively high LUS but no significant difference between groups [12.8 (2.6) vs 12.6 (2.6), p = 0.8].  Conclusion: Preterm infants managed with NIV-NAVA showed significantly higher DE compared to those managed on NIPPV. This study raises the hypothesis that NIV-NAVA could potentially improve diaphragmatic function due to its synchronization with patients' own breathing. Longitudinal studies to assess diaphragmatic function over time are needed.  Trial registry: Clinicaltrials.gov (NCT05079412). Date of registration September 30, 2021. What is Known: • NIV-NAVA utilizes diaphragmatic electrical activity to provide synchronized breathing support. • Evidence for the effect of NIV-NAVA on diaphragmatic thickness fraction (DTF) and excursion (DE) is limited. What is New: • Ultrasonographic assessment of diaphragmatic function (DTF and DE) is feasible. • In preterm infants, DE was significantly higher in infants supported with NIV-NAVA compared to those supported with NIPPV.

The use of neurally-adjusted ventilatory assist (NAVA) for infants with congenital diaphragmatic hernia (CDH)

OBJECTIVES

Newborns with congenital diaphragmatic hernia (CDH) can have complex respiratory problems which are worsened by ventilatory induced lung injury. Neurally adjusted ventilator assist (NAVA) is a potentially promising ventilation mode for this population, as it can result in improved patient-ventilator interactions and provision of adequate gas exchange at lower airway pressures.

CONTENT

A literature review was undertaken to provide an overview of NAVA and examine its role in the management of infants with CDH.

SUMMARY

NAVA in neonates has been used in CDH infants who were stable on ventilatory support or being weaned from mechanical ventilation and was associated with a reduction in the level of respiratory support.

OUTLOOK

There is, however, limited evidence regarding the efficacy of NAVA in infants with CDH, with only short-term benefits being investigated. A prospective, multicentre study with long term follow-up is required to appropriately assess NAVA in this population.

Proportional assist and neurally adjusted ventilation: Clinical knowledge and future trials in newborn infants

Different types of patient triggered ventilator modes have become the mainstay of ventilation in term and preterm newborn infants. Maintaining spontaneous breathing has allowed for earlier weaning and the additive effects of respiratory efforts combined with pre-set mechanical inflations have reduced mean airway pressures, both of which are important components in trying to avoid lung injury and promote normal lung development. New sophisticated modes of assisted ventilation have been developed during the last decades where the control of ventilator support is turned over to the patient. The ventilator detects the respiratory effort and adjusts ventilatory assistance proportionally to each phase of the respiratory cycle, thus enabling the patient to have full control of the start, the duration and the amount of ventilatory assistance. In this paper we will review the literature on the ventilatory modes of proportional assist ventilation and neurally adjusted ventilatory assistance, examine the different ways the signals are analyzed, propose future studies, and suggest ways to apply these modes in the clinical environment.

Neurally adjusted ventilatory assist in neonates with congenital diaphragmatic hernia

OBJECTIVE

To measure short-term outcomes of neonates with congenital diaphragmatic hernia (CDH) while on Neurally Adjusted Ventilator Assist (NAVA), and to measure the impact of a congenitally abnormal diaphragm on NAVA ventilator indices.

STUDY DESIGN

First, we conducted a retrospective-cohort analysis of 16 neonates with CDH placed on NAVA over a treatment period of 72 h. Second, we performed a case-control study comparing NAVA level and Edi between neonates with CDH and those without CDH.

RESULTS

Compared to pre-NAVA, there were clinically meaningful improvements in PIP (p < 0.003), Respiratory Severity Score (p < 0.001), MAP (p < 0.001), morphine (p = 0.004), and midazolam use (p = 0.037). Compared to a 1:2 matched group without CDH, there was no meaningful difference in NAVA level (p = 0.286), Edi-Peak (p = 0.315), or Edi-Min (p = 0.266).

CONCLUSIONS

The potential benefits of NAVA extend to neonates with CDH. There is minimal compensatory change in Edis, and higher/lower ventilator settings compared to neonates without CDH.

Feasibility of Non-invasive Neurally Adjusted Ventilator Assist After Congenital Diaphragmatic Hernia Repair

BACKGROUND

The use of neurally adjusted ventilator assist (NAVA) in congenital diaphragmatic hernia (CDH) patients has been historically deemed unwise, since the trigger for breaths is the electromyographic activity of the diaphragmatic muscle. We report on our NAVA experience in CDH patients.

METHODS

We performed an IRB-approved retrospective review of newborns from 1/1/2012-1/1/2017 at a Level I Children's Surgery Center undergoing CDH repair. Data obtained included demographics, defect type and repair, respiratory support, and outcomes.

RESULTS

Seven infants with CDH were placed on noninvasive-NAVA (NIV-NAVA) after extubation. All seven patients underwent open transabdominal repair, with five requiring patch repair. All survived to discharge, and one year after birth. When we compared this group to a contemporary cohort of patients who also underwent CDH repair, we found no significant differences in birth weight, postmenstrual age, or gender. However, there was a significantly higher need for inhaled nitric oxide (p = 0.002), high frequency oscillatory ventilation (p = 0.016), and extracorporeal membranous oxygenation support (p = 0.045) in the NIV-NAVA cohort.

CONCLUSION

This is the first report of NIV-NAVA being successfully utilized as an adjunct to wean infants from conventional ventilation after CDH repair, even in those who require patch repair or with more significant disease severity.

LEVELS OF EVIDENCE

III- Retrospective Comparative Study.

Application of Selective Bronchial Intubation versus Neurally Adjusted Ventilatory Assist in the Management of Unilateral Pulmonary Interstitial Emphysema: An Illustrative Case and the Literature Review

In the treatment of left-sided pulmonary interstitial emphysema (PIE) in a 23-week neonate, we used two ventilatory strategies: selective bronchial intubation from day 10 to 15 and neurally adjusted ventilatory assist (NAVA) from day 18 to 26. We compared the effects and adverse effects of these two strategies. On selective bronchial intubation, desaturation was frequent. Fentanyl infusion was required. There was an episode of carbon dioxide retention coupled with hypotension. On NAVA, the neonate was clinically stable without the requirement of sedation. On selective bronchial intubation, ventilator setting in terms of mean airway pressure and oxygen requirement was higher, which came down on the first day of NAVA. Radiologically unilateral PIE did not resolve and became localized in the left middle zone of lung field on selective bronchial intubation. Also, the lobar collapse of ipsilateral, as well as contralateral lungs occurred. On NAVA, unilateral PIE resolved. NAVA might be a good option for the management of unilateral PIE.

Neurally Adjusted Ventilatory Assist for Noninvasive Support in Neonates

Noninvasive ventilation (NIV) is frequently used in the NICU to avoid intubation or as postextubation support for spontaneously breathing infants experiencing respiratory distress. Neurally adjusted ventilatory assist (NAVA) is used as a mode of noninvasive support in which both the timing and degree of ventilatory assist are controlled by the patient. NIV-NAVA has been successfully used clinically in neonates as a mode of ventilation to prevent intubation, allow early extubation, and as a novel way to deliver nasal continuous positive airway pressure.

Case report: Non-invasive neurally adjusted ventilatory assist in a newborn with unilateral diaphragmatic paralysis

Diaphragmatic paralysis is a rare cause of respiratory distress in the newborn. In this paper, a patient with unilateral phrenic nerve injury after traumatic delivery is presented. The child inadequately responded to standard respiratory supportive measures. Non-invasive neurally adjusted ventilatory assist (NIV-NAVA®), providing an optimally synchronized respiratory support proportional to the effort of the patient, resulted in prompt clinical and biological improvement of the patient's respiratory condition. NAVA is a relatively new mode of ventilation in neonatal care. In this case of unilateral diaphragmatic paralysis, it provided an alternative strategy of non-invasive respiratory support avoiding prolonged mechanical ventilation. Pediatr Pulmonol. 2016;51:E37-E39. © 2016 Wiley Periodicals, Inc.

Non-invasive ventilation with neurally adjusted ventilatory assist in newborns

Neurally adjusted ventilatory assist (NAVA) is a mode of ventilation in which both the timing and degree of ventilatory assist are controlled by the patient. Since NAVA uses the diaphragm electrical activity (Edi) as the controller signal, it is possible to deliver synchronized non-invasive NAVA (NIV-NAVA) regardless of leaks and to monitor continuously patient respiratory pattern and drive. Advantages of NIV-NAVA over conventional modes include improved patient-ventilator interaction, reliable respiratory monitoring and self-regulation of respiratory support. In theory, these characteristics make NIV-NAVA an ideal mode to provide effective, appropriate non-invasive support to newborns with respiratory insufficiency. NIV-NAVA has been successfully used clinically in neonates as a mode of ventilation to prevent intubation, to allow early extubation, and as a novel way to deliver nasal continuous positive airway pressure. The use of NAVA in neonates is described with an emphasis on studies and clinical experience with NIV-NAVA.

Current concepts in acute respiratory support for neonates and children

Current trends in mechanical respiratory support are evolving toward gentle approaches to avoid short- and long-term problems that are historically associated with mechanical ventilation. These ventilator-associated issues include the need for long-term sedation, muscle deconditioning, ventilator-associated lung injury (VALI), and ventilator-associated pneumonia (VAP). This article will describe recent trends of ventilatory support in neonates and children: (1) utilization of volume ventilation in infants, (2) synchrony and improving patient-ventilator interaction specifically using neurally adjusted ventilatory assist (NAVA), and (3) use of noninvasive ventilation techniques. When applicable, their uses in the surgical newborn and pediatric patients are described.

Neonatal ventilation strategies and long-term respiratory outcomes

Long-term respiratory morbidity is common, particularly in those born very prematurely and who have developed bronchopulmonary dysplasia (BPD), but it does occur in those without BPD and in infants born at term. A variety of neonatal strategies have been developed, all with short-term advantages, but meta-analyses of randomized controlled trials (RCTs) have demonstrated that only volume-targeted ventilation and prophylactic high-frequency oscillatory ventilation (HFOV) may reduce BPD. Few RCTs have incorporated long-term follow-up, but one has demonstrated that prophylactic HFOV improves respiratory and functional outcomes at school age, despite not reducing BPD. Results from other neonatal interventions have demonstrated that any impact on BPD may not translate into changes in long-term outcomes. All future neonatal ventilation RCTs should have long-term outcomes rather than BPD as their primary outcome if they are to impact on clinical practice.