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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
A comparison of 2 modes of non-invasive ventilation applied on patients after extubation
Scientific title
Noninvasive ventilation-neurally adjusted ventilatory assist (NIV-NAVA) compared to noninvasive ventilation-pressure support (NIV-PS) in post-extubated subjects on synchrony and work of breathing
Secondary ID [1] 283038 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Respiratory failure 289873 0
Condition category
Condition code
Respiratory 290234 290234 0 0
Other respiratory disorders / diseases

Study type
Description of intervention(s) / exposure
use of non-invasive ventilation in the neurally adjusted ventilatory assist mode (NIV-NAVA) with PEEP set at 5 cmH2O. NAVA gain level will be titrated to achieve an equivalent peak inspiratory pressure as in PSV (NAVA0). Another 2 levels will be set at 0.5 cmH2O/uV above and below NAVA0 (NAVA+1 and NAVA-1 respectively). Inspiratory trigger Edi will be set at 0.5uV above Edi min, while expiratory trigger is fixed by the manufacturer at 70% of Edi peak. The subject will breathe at each setting for 20 minutes as wash-out and recordings are obtained in the next 2 minutes.
Intervention code [1] 287758 0
Treatment: Devices
Comparator / control treatment
non-invasive ventilation in the pressure support mode (NIV-PS) with PEEP set at 5 cmH2O, PS titrated to achieve a tidal volume of 6-8ml/kg, inspiratory flow trigger at 5, expiratory trigger at 30% of maximal peak flow, rise time at 0.1 ms. The subject will breathe at this setting for 20 minutes and recordings are obtained in the next 2 minutes
Control group

Primary outcome [1] 290255 0
% of patient-ventilator asynchrony index will be measured by studying airway pressure, flow (obtained using the Servo Tracker software) and esophageal pressure tracings measured using a balloon esophageal catheter, an analog-to-digital converter system and Labview software.
Timepoint [1] 290255 0
at the end of 20 minutes on each NIV setting
Primary outcome [2] 290256 0
inspiratory work of breathing will be measured using the diagram method of Campbell by integrating the area plotted between the esophageal pressure-volume and chestwall compliance curves. Esophageal pressure-time-product will also be calculated.
Timepoint [2] 290256 0
measured at the end of 20 minutes of each NIV setting
Secondary outcome [1] 304215 0
patient's comfort score assessed by a visual analog scale
Timepoint [1] 304215 0
measured at the end of 20 minutes on each NIV setting

Key inclusion criteria
1. Are currently or previously on mechanical ventilation for acute respiratory failure
2. Are considered fit for extubation (defined as hemodynamic stability without the need for vasopressor support and a heart rate less than 110 beats per minute (bpm), respiratory rate less than 30 per minutes, and a Glasgow coma scale of E4VtM6), or has been extubated already
3. Are indicated for NIV with >=1 of the risk factors for reintubation, including: chronic heart failure, COPD initially intubated because of an episode of acute hypercapnic respiratory failure, age >65, more than one consecutive failure of weaning trial before extubation, PaCO2 >45 mmHg (6 kPa) after extubation, weak cough
4. Expected to require NIV for >=2 days
5. Able to give consent to the study by him/herself.
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
patients less than 18 years of age, pregnancy, with contraindications for insertion of nasogastric tube, or with contraindications for NIV (esophageal varices or obstruction, bleeding of the upper gastrointestinal tract, recent gastroesophageal surgery, hemodynamic instability or severe arrhythmia, facial surgery or trauma or deformity, severe upper airway obstruction, inability to cooperate or protect the airways, inability to cough or clear respiratory secretions, absence of a gag reflex and severe gastric distention), or contraindications to NAVA mode (known or suspected phrenic nerve dysfunction, and impaired respiratory drive).

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
This is a cross-over study. After extubation, each subject will receive NIV in both NAVA and PS modes but in a random sequence.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
4 pieces of paper labelled as PS mode, NAVA0, NAVA-1 and NAVA+1 are folded and placed inside a paper bag. The sequence of NIV levels per subject is determined by the sequence of paper drawn from the paper bag.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Prior studies provided only non-parametric data. Reduction in the median asynchrony index using NIV-NAVA compared to NIV-PS was 10.9% (from 15.8% (interquartile range, IQR 5.5-49.6%) to 4.9% (IQR 2.5 – 10.5 %) using data from Piquilloud et al 2012. With an estimated standard deviation of 13, a power of 90% and an alpha error of 5%, and using paired t test, the sample size calculated is 17.
Results will be presented as mean +/- SD. Comparisons between NIV-PS and NIV-NAVA will be done using the Mann-Whitney U test. P values of 0.05 or less will be considered significant.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 5315 0
Hong Kong
State/province [1] 5315 0

Funding & Sponsors
Funding source category [1] 287801 0
Name [1] 287801 0
Department of Intensive Care, Pamela Youde Nethersole Eastern Hospital
Address [1] 287801 0
3 Lok Man Road, Chai Wan, Hong Kong
Country [1] 287801 0
Hong Kong
Primary sponsor type
Department of Intensive Care, Pamela Youde Nethersole Eastern Hospital
3 Lok Man Road, Chai Wan, Hong Kong
Hong Kong
Secondary sponsor category [1] 286530 0
Name [1] 286530 0
Address [1] 286530 0
Country [1] 286530 0

Ethics approval
Ethics application status
Ethics committee name [1] 289748 0
Hong Kong East Cluster Ethics Committee
Ethics committee address [1] 289748 0
Pamela Youde Nethersole Eastern Hospital,
3 Lok Man Road, Chai Wan
Ethics committee country [1] 289748 0
Hong Kong
Date submitted for ethics approval [1] 289748 0
Approval date [1] 289748 0
Ethics approval number [1] 289748 0

Brief summary
Noninvasive ventilation (NIV) has been found to reduce ventilator associated pneumonia, total duration of mechanical ventilation, length of intensive care unit (ICU) and hospital stay and mortality in patients with respiratory failure when they are connected after extubation. However, this benefit will be annihilated if NIV cannot be tolerated by the patient. Because NIV is delivered through an interface prone to leakage in a conscious but not necessarily cooperative patient, there could be more problems in patient-ventilator synchrony as compared to invasive positive pressure ventilation (IPPV). NAVA was found to be able to improve patient-ventilator synchrony through its benefits in better ventilator triggering and cycling off using the electrical activity of the diaphragm (Edi) signal instead of pressure or flow changes in the ventilator circuit. This could translate into a reduction in the work of breathing (WOB) as has been found in an animal study using NAVA in IPPV, but detailed analysis of WOB in NIV-NAVA has not been reported. We hypothesized that patient-ventilator asynchrony and WOB would be reduced using NAVA-NIV.
The aim of this study is therefore to find out whether there would be a reduction in asynchrony and WOB using NIV-NAVA compared with standard NIV-PS, and to find out its comparative benefits in post-extubation NIV.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 42234 0
Dr LAM Sin-Man
Address 42234 0
Department of Intensive Care, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan
Country 42234 0
Hong Kong
Phone 42234 0
Fax 42234 0
Email 42234 0
Contact person for public queries
Name 42235 0
Dr LAM Sin-Man
Address 42235 0
Department of Intensive Care, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan
Country 42235 0
Hong Kong
Phone 42235 0
Fax 42235 0
Email 42235 0
Contact person for scientific queries
Name 42236 0
Dr LAM Sin-Man
Address 42236 0
Department of Intensive Care, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan
Country 42236 0
Hong Kong
Phone 42236 0
Fax 42236 0
Email 42236 0

No information has been provided regarding IPD availability
Summary results
No Results