Title: A randomised feasibility study examining neurally-adjusted ventilatory assist (NAVA) in patients at high risk of prolonged ventilatory failure during recovery from critical illness.
Funder: Health Education England

Abstract: BACKGROUNDInvasive ventilation is a key ICU treatment and a key nursing responsibility. More than 1300 patients per year in our ICU alone receive this treatment. It can be life-saving, but prolonged ventilation is common, and is associated with increased morbidity and mortality and with long term physical and cognitive problems. The economic cost is significant; ventilated patients consume disproportionate amount resource. Those ventilated for greater than 7 days, although only around 7% of the total ICU admissions, can consume over 50% of total ICU resources. This problem is set to get worse with increasing admissions, age and comorbidities. Research to this point has focused on sedation limitation and protocolised care, but it is now clear that interaction between the patient and the ventilator and rapid adaptation of the support to the changing patient, are major factors determining the duration of ventilation. Neurally Adjusted Ventilatory Assist (NAVA) addresses these issues by allowing the patient's neural signals diaphragmatic signals detected via a feeding catheter to control the mechanical ventilator, thereby using the patient's own complex feedback mechanisms to provide perfectly synchronous and adaptive support.As yet there are no prospective, randomised trials assessing the effect on duration of ventilation or sedation. There is an ever growing international recognition of the need for such research, and King's College Hospital is currently the only hospital in the UK with the technology, the clinical and the research expertise necessary to conduct this study. I am now proposing a feasibility stage study, randomising high risk patients to standard care or NAVA, to inform a later randomised controlled trial. METHODS This study aims to inform the design of a multi-centre RCT by undertaking feasibility testing and evaluation of the proposed NAVA intervention. Main outcomes include: Following the feasibility stage, a multi-site RCT is planned to assess the effect of NAVA technology on a) duration of ventilation b) sedative / analgesic / hypnotic use in critically ill adult patients at risk of prolonged ventilatory weaning. The definitive RCT phase is beyond the scope of this Fellowship. A UK wide NAVA group has been established and is in agreement about conducting this multi-site study following this initial single site feasibility phase. Design A single centre randomised feasibility study. Group one will receive standardised weaning care while group two will receive standardised weaning care with the addition of NAVA technology. Other aspects of weaning care will be standardised in both groups through the use of local protocols and guidelines. Population Intubated and ventilated adult patients who are at greatest risk of difficult or prolonged weaning: Those with pre-existing cardiopulmonary dysfunction. Outcomes Primary feasibility outcomes includeassessment of the ability to recruitprotocol compliance and acceptability to clinicianssample size determination for proposed subsequent Randomised Controlled TrialOther outcomes include: Staff attitudes, knowledge and training needs, ventilator free days (intended primary outcome of main study); total analgesia and hypnotic agents in ICU; non-invasive measurement of neural respiratory drive (parasternal electromyography); agitation / comfort; patient-ventilator interaction (aysynchrony); health related quality of life; and Health Resource Group costs. BENEFITS This study has important clinical and cost implications for the management of patients who require ventilatory support during critical illness. It will also convey operational, safety and educational benefits to the ICU staff involved. Main anticipated benefits include: Reduced duration of mechanical ventilation and associated risks Reduced volume of sedative/analgesic medications and associated risk Improved patient comfort Improved staff knowledge of currently used NAVA technology and respiratory physiology Improved understanding of breathlessness and associated clinical problems Improved understanding of patient experience of ICU treatment, and particularly ventilation

Lay abstract: Many patients admitted to intensive care have heart or lung problems. Patients with these conditions often require help with their breathing. Survival and long-term recovery are improved if we can remove the breathing support quickly. Reducing the support quickly is not only beneficial to the patient but also saves the NHS money. In this study, I will focus on patients with severe lung or heart disease to examine whether a particular type of breathing machine (NAVA ventilator) improves comfort, reduces the need for sedative drugs and helps patients come off breathing support quicker with improved long term outcomes.

Research activity codes: 6.3 MEDICAL DEVICES
Health categories: RESPIRATORY;CARDIOVASCULAR