In emergency medicine positive pressure ventilation (PPV) refers to the process of forcing air into the lungs of a (usually apneic or dyspneic) patient, usually using a bag valve mask (BVM) or mechanical ventilator.
During normal breathing, air is drawn into the lungs from the outside by the expansion of the chest wall and contraction of the diaphragm to increase volume inside the thoracic cavity. If the airway is sealed, the expansion of the thoracic cavity creates negative pressure inside the lungs relative to the atmospheric pressure outside the body. Hence, during normal breathing air is said to be drawn into the lungs by negative pressure. Positive pressure ventilation, however, works by forcing air into the lungs and thereby increasing the pressure inside the airway relative to the outside. Hence the name "positive pressure." Aside from the obvious advantage of ventilating an otherwise apneic or dyspneic patient, PPV can be effectively used in the treatment of flail segments, which characteristically render negative pressure breathing ineffective, but does not impede PPV.
Positive pressure ventilation is also used in fire fighting to blow smoke out of a room or structure. See Ventilation (firefighting)
See also
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