(NIV) mechanical assistance with breathing that does not require the insertion of an endotracheal tube (see intubation). In noninvasive intermittent positive-pressure ventilation (NIPPV) air is blown into the lungs through a close-fitting mask: designs range from helmet-like devices to nasal cushions and full-face or nasal masks (see also Nippy). A ventilator then applies positive pressure to the mask in a cyclical fashion. The technique simplifies the process of ventilation in respiratory failure and reduces or eliminates the need for paralysis and anaesthesia, which are required for endotracheal intubation. See also BiPAP; continuous positive airways pressure.
Negative-pressure ventilation involves the use of devices that draw air into and out of the lungs noninvasively by applying negative pressure in a cyclical way (see ventilator).
When we breathe in, the outward movement of the chest increases the volume of the lungs and the pressure in them falls below that of the outside world. Therefore, air is drawn in automatically. When we breathe out, some air exits because of the normal elastic recoil of the lungs, but we also force air out by using the muscles of the chest and the DIAPHRAGM. Replicating this arti?cially involves using a device to produce intermittent positive or negative pressure ventilation as described below.... artificial ventilation of the lungs
The procedure, usually carried out in an operating theatre or intensive-care unit, in which a device called a VENTILATOR takes over a person’s breathing. This is done for someone who is unable to breathe normally. Damage to the respiratory centre of the brain as a result of head injury, disease of the brain, or an overdose of sedative or narcotic drugs may affect the respiratory centre. Chest injuries, disease of the lungs, nerve or muscle disorders or surgery of the chest or abdomen can also affect breathing and require the use of a ventilator to maintain normal breathing. Arti?cial ventilation can also be carried out as an emergency by mouth-to-mouth resuscitation. (See also ANAESTHESIA; ARTIFICIAL VENTILATION OF THE LUNGS.)... ventilation, artificial
(V/Q scanning) a nuclear medicine technique in which two different isotopes are used, one inhaled (usually *xenon-133 or *krypton-81m), to examine lung ventilation, and the other injected into a vein, to examine lung perfusion. In *pulmonary embolism, the area of lung supplied by the blocked artery is not being perfused with blood – which gives a perfusion defect on the film – but has normal ventilation. This technique is highly sensitive for pulmonary embolism.... ventilation-perfusion scanning
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