The field of ventilatory support has changed dramatically with the introduction of improvements in technology and new ventilatory modes. The most recent ventilators are characterized by microprocessor technology, making the interaction between patient and ventilator more sophisticated than ever before. This technology has enabled the development of pressure support ventilation, which has gained extensive popularity during the past 10 years. Pressure support ventilation is different from controlled mechanical ventilation or intermittent mandatory ventilation; pressure support ventilation is characterized by a unique combination of simultaneous spontaneous and mechanical breathing, so that the ventilatory and flow rates and tidal volume depend on the patient's breathing pattern and the set level of pressure support. Pressure support ventilation can be used as a stand-alone ventilatory support mode and alternative to volume-controlled ventilation, and it can be used in weaning patients from mechanical ventilation.