Comparative Effects of Variable Pressure Support, NAVA and PAV

Study Overview
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Brief Summary
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Experimental animal data suggest that increasing breathing pattern variability in mechanical ventilation could be beneficial. Variable ventilation can be induced through the following modes: Neurally Adjust Ventilatory Assist (NAVA), Proportional Assist Ventilation (PAV) and Variable-Pressure Support Ventilation (V-PSV). These modes have not yet been compared to each other. Pilot observations in our department suggest a feasibility in patients. The objectives of the study are to compare the impact of PSV, NAVA, PAV and V-PSV on the variability of the breathing pattern, patient-ventilator asynchrony, risk of lung overdistension, gas exchange, and repartition of ventilation.

Detailed Description
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Cross-over, prospective, randomized controlled monocentric trial . Patients on pressure support ventilation will be ventilated with PSV, NAVA, PAV, and V-PSV (in a randomized sequence). In each mode the level of assistance will be set to achieve a similar tidal volume of 6-8 ml/kg. The following data will be measured and recorded: airway flow and pressure, electrical activity of the diaphragm (EAdi), blood gases, electrical impedance tomography, end tidal partial pressure in carbon dioxide (PEtCO2). Will be calculated: the coefficient of variation (CV, standard deviation (SD)/mean) of the peak pressure (Ppeak), EAdi and of the main descriptors of the breathing pattern, the prevalence of the main patient-ventilator asynchronies, the prevalence of tidal volume (VT) >10ml/kg, ventrodorsal repartition of ventilation and inhomogeneity index, dead space

Official Title
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Comparative Effects of Variable Pressure Support, Neurally Adjusted Ventilatory Assist (NAVA) and Proportional Assist Ventilation (PAV) on the Variability of the Breathing Pattern and on Patient Ventilator Interaction

Conditions
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Respiratory Failure

Intervention / Treatment
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* Device: PSV, NAVA, PAV, Variable-PSV


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patient on mechanical ventilation for >48 h estimated duration of mechanical ventilation >24h hemodynamic stability Exclusion Criteria: pregnancy impossibility to insert an EAdi catheter neuromuscular disease, phrenic nerve lesions

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: PSV, PAV, NAVA, Variable-PSV<br>This is a crossover study in which each patient will be ventilated in the following modes of mechanical ventilation: Pressure Support Ventilation (PSV), Neurally Adjusted Ventilator Assist (NAVA), Proportional assist ventilation (NAVA) and variable Pressure Support Ventilation (Variable-PSV), in a randomised order. | Device: PSV, NAVA, PAV, Variable-PSV<br>* Each patient enrolled in the study will be ventilated in all the following modes: PSV, NAVA, PAV and variable PSV<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Coefficient of variation of the tidal volume (VT) | Coefficient of variation (standard deviation/mean) of the tidal volume (VT) | 1 hour | 
| Coefficient of variation of the respiratory rate (RR) | Coefficient of variation (standard deviation/mean) of the respiratory rate (RR) | 1 hour | 
| Coefficient of variation of the inspiratory time (Ti) | Coefficient of variation (standard deviation/mean) of the inspiratory time (Ti) | 1 hour | 
| Coefficient of variation of the electrical activity of the diaphragm (EAdi) | Coefficient of variation (standard deviation/mean) of the electrical activity of the diaphragm (EAdi) | 1 hour | 
| Coefficient of variation of the maximal inspiratory pressure (Ppeak) | Coefficient of variation (standard deviation/mean) of the maximal inspiratory pressure (Ppeak) | 1 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patient ventilator asynchrony | asynchrony index (composite outcome, that includes double triggering, auto triggering and ineffective efforts) ) | 1 hour | 
| Safety from lung overdistension, assessed by the proportion of tidal volumes (VT) >10 ml/kg |  | 1 hour | 
| Gas exchanges | Ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2), arterial carbon dioxide pressure (PaCO2) | 6 hours | 
| Repartition of ventilation measured by electrical impedance tomography |  | 6 hours | 
| Dead space to tidal volume ratio (Vd/Vt) | Vd/Vd, is a ratio between two volumes | 6 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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PAV, mechanical ventilation, pressure support ventilation, NAVA, variable ventilation, patient ventilator asynchrony