Study of the Benefit of the NAVA Mode Versus PSV Mode on Patient Ventilator Asynchrony During Non Invasive Ventilation With Helmet

Non invasive ventilation has been proposed to reduce the incidence of ventilatory dysfunction following abdominal aortic surgery. However, the nasogastric tube reduces the airtightness of the facial mask used to perform non invasive ventilation and induces air leaks. The use of a helmet reduces air leaks, thus seems adequate to ensure patient-ventilator interface. However, the high dead space related to helmet volume is responsible for asynchrony between patient demand and ventilatory support delivery. The investigators hypothesized driving the ventilator based on a neural signal (diaphragm electrical activity) would reduce patient-ventilator asynchronies.