Abstract

Julia HarrisNeurally Adjusted Ventilatory Assist in infants with acute viral bronchiolitis (NAVABronch study) - A mixed methods Feasibility study To establish the evidence and to evaluate the effectiveness of neurally adjusted ventilatory assist in infants with acute viral bronchiolitis. Abstract AimThe aim of this mixed-methods thesis is to evaluate the use of Neurally Adjusted Ventilatory Assist (NAVA) in infants with acute viral bronchiolitis. BackgroundThere are currently 6,662 infants less than one year of age with a primary respiratory diagnosis admitted to Paediatric Intensive Care Units (PICUs) in the UK each year. Respiratory illness is more common in winter, with the commonest diagnosis in infants being acute viral bronchiolitis (AVB). Provision of mechanical ventilation in infants with AVB is challenging due to the inflammatory nature of the illness and infants’ respiratory anatomy. There is no recommended standardised ventilation strategy internationally for this infant population, resulting in an inconsistent approach in care and variation in patient outcomes. Conventional modes of ventilation typically result in patient-ventilator asynchrony, with subsequent increased work of breathing. NAVA is a mode of pressure supported ventilation that is triggered by neural diaphragmatic electric activation, and is thus physiologically similar to normal breathing patterns, which may improve patient-ventilator synchrony. This mode of ventilation may also require less sedation. However, there is little guidance on the use of NAVA in infants with acute respiratory failure, particularly in those with AVB. This represents a significant gap in our knowledge base.Methods:Firstly, a scoping review to map the current evidence on suggested NAVA settings, outcome measures, and sedation practices in infants with acute respiratory failure (ARF) was conducted. This was used to inform the design of a single site mixed-methods feasibility study. Secondly, a cross-over feasibility RCT, with an embedded mechanistic study evaluating the effectiveness of NAVA focusing on two different sedation doses and titration of NAVA and PEEP levelsand a qualitative study exploring staff and parent experiences of NAVA and being involved in the RCT was designed.FindingsThe scoping review identified that there were no current recommendations for setting NAVA and PEEP levels or guidance regarding sedation strategies in infants with ARF. The RCT found that analgosedation using intravenous morphine at a dose of 20mcg/kg/hr, compared to 5mcg/kg/hr, was preferable in this patient group, and that Positive End Expiratory Pressure (PEEP) of 10cmH20 appeared to improve respiratory efficiency and drive. An optimum NAVA level of support was not identified. Parents and staff found that the RCT was acceptable. Together these findings may help to inform a future definitive RCT.ConclusionA feasibility RCT has been conducted that is safe and acceptable. The thesis has contributed to and challenged existing knowledge and has identified clear recommendations related to study design, procedures and outcomes for a future trial. The outcomes of a definitive RCT could inform new standards for mechanically ventilated infants with AVB, something that is currently lacking

Document Type

Thesis

Publication Date

2025

Download

Share

COinS