Biphasic Positive Airway Pressure (BIPAP)

During the past few years, research in the field of ventilatory support [1] has mainly focused on the development of modes combining mechanical ventilation with spontaneous breathing (augmented ventilation). Mechanical ventilation can be combined with spontaneous breathing either by intermittent administration (mechanical breath — spontaneous breath) or by providing continuous ventilatory support during every breath. The first of these two principles is utilized by all modes of intermittent mandatory ventilation (IMV); the second principle is the basis of the large variety of inspiratory assists (IA). Both strategies aim at mechanically assisting patients with insufficient spontaneous ventilation by using an artificial ventilation system which provides part of the ventilatory work. In order to improve the gas exchange for oxygen, an appropriate amount of lung volume at end-expiration must be maintained by positive end-expiratory pressure (PEEP, CPAP). Biphasic positive airway pressure (BIPAP), which is described in the following, is an attempt at providing ventilatory support with the CPAP function of the respirator.