Neurally adjusted ventilatory assist can be used to wean infants with congenital diaphragmatic hernias off respiratory support

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.

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.

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.

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.