(bi-level positive airways pressure) trade name for a device that provides ventilation for patients by delivering air to the lungs at two levels of pressure, either cyclically in an anaesthetized patient or triggered by the patient’s attempts at breathing when awake. The higher pressure inflates the lungs to whatever volume can safely be achieved, while the lower pressure enables controlled exhalation against a resistance: this minimizes *atelectasis, a risk with conventional positive-pressure ventilators, which allow exhalation against zero resistance (by opening a valve in the device). Although BiPAP is a trade name, it is now widely used generically for this type of ventilation (or ventilator). There are also other devices that utilize the same principle, for example vPAP (variable positive airways pressure).
n. 1. a device to ensure a supply of fresh air. 2. (respirator) equipment that is manually or mechanically operated to maintain a flow of air into and out of the lungs of a patient who is unable to breathe normally. Positive-pressure ventilators blow air into the patient’s lungs; air is released from the lungs when the pressure from the ventilator is relaxed (see BiPAP; Nippy; noninvasive ventilation). Negative-pressure ventilators are airtight containers in which the air pressure is decreased and increased mechanically. This draws air into and out of the patient’s lungs through the normal air passages. The original devices, known colloquially as iron lungs, had a seal around the neck and enclosed the whole body except the head. They have been replaced by cuirass ventilators, which work on a similar principle but enclose the chest only; there may be a role for these in adults and children with claustrophobia.... ventilator
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