Effects of Abnormal Respiratory Mechanics and Assisted Mechanical Ventilation on Neuro-regulation of Respiration

Effects of Abnormal Respiratory Mechanics and Assisted Mechanical Ventilation on Neuro Regulation of Respiration

Due to recent technological improvements, it is now possible to record the electrical activity of the diaphragm (Eadi), a direct expression of the central nervous system respiratory center activity. By providing a relatively easy-to-use technique to record Eadi the NAVA (Neurally Adjusted Ventilatory Assist) technology offers a new opportunity to explore the effects of various interventions on neural inspiratory activity in human subjects during spontaneous and assisted ventilation both for normal and simulated abnormal respiratory mechanics.

The main aim of this project is to measure and compare the components of Eadi signal, the direct reflect of the respiratory centers activity, under various conditions of normal and simulated altered respiratory mechanics (either obstructive or restrictive respiratory mechanics° in order to better understand the neuroregulation of breathing. The second aim of the present project is to perform a similar analysis regarding the effects of various modes (Pressure Support and NAVA) and various levels of assisted ventilation both in case of normal and abnormal respiratory mechanics. Based on the information recorded on Eadi and flow and pressure signals, the last aim of this project is to correlate Eadi and pneumatic derived parameters both during spontaneous breathing and assisted ventilation.

Practically, by using the NAVA recording technology, the investigators will perform a physiological study on normal volunteers to explore the effects of normal and simulated abnormal respiratory mechanics on Eadi, flow and pressure signals (airway, oesophageal and transdiaphragmatic pressures) in order to better understand the neuroregulation of breathing. Thirty healthy volunteers with documented normal lung function tests will be included in the study (obstructive respiratory mechanics will be simulated in 15 healthy volunteers and respiratory mechanics will be simulated in 15 healthy volunteers).

Inclusion Criteria:

• Man ;
• Less than 35 years old ;
• Non obese (BMI <30 kg/m2) ;
• Normal pulmonary function tests (vital capacity and forced expiratory volume in one second in the normal range for the age and size)
• No history of respiratory disease (asthma, pneumothorax) ;
• No contraindication for nasogastric tube placement

Exclusion Criteria:

• Active or past respiratory disease ;
• Contraindication to nasogastric tube placement ;
• Less than 18 years old;
• Subject protected by the law (eg subject incapable of discernment, wardship subject, ...) ;
• Subject not covered by a social security system ;
• Subject with a subordination relationship with a member of the research team.