Crossover study of assist control ventilation and neurally adjusted ventilatory assist
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Some studies of infants with acute respiratory distress have demonstrated that neurally adjusted ventilator assist (NAVA) had better short-term results compared to non-triggered or other triggered models. We determined if very prematurely born infants with evolving or established bronchopulmonary dysplasia (BPD) had a lower oxygenation index (OI) on NAVA compared to assist control ventilation (ACV). Infants were studied for 1 h each on each mode. At the end of each hour, blood gas analysis was performed and the OI calculated. The inspired oxygen concentration (FiO2), the peak inflation (PIP) and mean airway pressures (MAP) and compliance were averaged from the last 5 min on each mode. Nine infants, median gestational age of 25 (range 22–27) weeks, were studied at a median postnatal age of 20 (range 8–84) days. The mean OI after 1 h on NAVA was 7.9 compared to 11.1 on ACV (p = 0.0007). The FiO2 (0.36 versus 0.45, p = 0.007), PIP (16.7 versus 20.1 cm H2O, p = 0.017) and MAP (9.2 versus 10.5 cm H2O, p = 0.004) were lower on NAVA. Compliance was higher on NAVA (0.62 versus 0.50 ml/cmH2O/kg, p = 0.005).
What is Known:
• Neurally assist ventilator adjust (NAVA) uses the electrical activity of the diaphragm to servo control the applied pressure.
• In infants with acute RDS, use of NAVA was associated with lower peak inflation pressures and higher tidal volumes.
What is New:
• This study uniquely reports infants with evolving or established BPD, and their results were compared on 1 h each of NAVA and assist controlled ventilation.
• On NAVA, infants had superior (lower) oxygen indices, lower inspired oxygen concentrations and peak and mean airway pressures and higher compliance.
KeywordsAssist control ventilation Neurally adjusted ventilatory assist Prematurity
Assist control ventilation
Electrical activity of the diaphragm
Inspired oxygen concentration
Mean airway pressures
Neurally assist ventilator adjust
Positive end expiratory pressure
Peak inflation pressure
Respiratory distress syndrome
Professor Greenough and Dr. Ali designed the study and approved the final manuscript as submitted. Dr. Shetty and Dr. Hunt collected the data and approved the final manuscript as submitted. Professor Peacock designed the statistical analysis and analysed the data and approved the final manuscript as submitted. All authors were involved in the preparation of the manuscript and approved the final manuscript as submitted.
Compliance with ethical standards
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Dr. Hunt is supported by a grant from the Charles Wolfson Charitable Trust. Dr. Shetty was supported by funding from King’s College Hospital NHS Foundation Trust in recognition of Professor Greenough’s NIHR Senior Investigator Award. The research was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.
Conflict of interest
AG has held grants from various ventilator manufacturers and has received honoraria for giving lectures and advising various ventilator manufacturers. The Servo-n ventilator was loaned to us by Marquet Critical Care, Solna, Sweden. They were not involved in the study design, data collection, data analysis or production of the manuscript.
Infants whose parents gave informed written consent were recruited.