During the 1970s and 1980s medical ventilators were developed which allowed patients breathe spontaneously, initially with assisted breaths (assist control ventilation) and subsequently with spontaneous breathing limbs-(synchronized) intermittent mandatory ventilation (SIMV). The latter was the first mode to allow partial ventilatory support and thus gradual liberation from the medical ventilator. Pressure support was initially developed as a method of lending partial support to the patient's spontaneous breaths, and interactivity became a function of microprocessor driven  ventilators. Physicians rapidly discovered that this could be used as a primary ventilation mode, with full patient interaction. Using the medical ventilator as an interactive weaning device emerged at this time.

 

During the 1990s widespread concern developed about medical ventilator induced lung injury. Accumulating evidence revealed that larger tidal volume, low PEEP, ventilation strategies were damaging the lungs. This has led to the development of lung protective ventilator strategies, using PEEP to maintain alveolar recruitment (the 'open lung' approach), and lower tidal volumes, leading to reduced end inspiratory volumes, to prevent stretch injury. There was renewed interest in plateau pressure limitation and increasing mean airway pressures. Various strategies have been developed to achieve this goal. Pressure controlled ventilation has emerged as a viable alternative, although all strategies involve tidal volume targeting.