Hypothesis: The principal hypothesis is that FreeO2 is possible and well-accepted by nurses and medical personnel and there are advantages to use this system. In comparison with the common oxygen delivery (the rotameter), the hypothesis is that FreeO2 system will make for a better control of the oxygen saturation in function of designed target, reducing the desaturation time and hyperoxia. We think that oxygen weaning will be faster than classical way if it is automated. In addition, FreeO2 could reduce the number of intervention by nurse personnel.