Ventilation mécanique : modes de référence

The objective of mechanical ventilation is to make up partially or totally for respiratory pump of patient. The way with which ventilator insufflates gaseous mixture is called ventilatory mode. When a ventilatory cycle is initiated, the regulated physiological variable can be the circulating flow or the pressure in the airways. In the first case, the parameter set by the clinician is the volume delivered at each cycle called tidal volume, in the second case, the set parameter is the insufflation pressure. A ventilatory cycle can be initiated by the machine (controlled cycle) or by the patient (assisted cycle) and it also can be terminated by the ventilator or the patient. If a cycle is initiated and terminated by the patient, we speak about spontaneous cycle. All this elements allow to define the ventilatory modes of reference which are “historically” the assisted controlled volume ventilation, the assisted controlled pressure ventilation and the pressure support ventilation. Development of these modes has been correlated with the technical evolution of ventilators. Today, industrial supply is constituted of a lot of ventilatory modes where pressure and volume attempt to be regulated jointly, whereas clinical recommendations are based quasi exclusively on the utilisation of modes of reference.