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Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation.The mode refers to the method of inspiratory support. In general, mode selection is based on clinician familiarity and institutional preferences, since there is a paucity of evidence indicating that the mode affects clinical outcome.
With conventional ventilation where tidal volumes (V T) exceed dead space (V DEAD), gas exchange is largely related to bulk flow of gas to the alveoli.With high-frequency ventilation, the tidal volumes used are smaller than anatomical and equipment dead space and therefore alternative mechanisms of gas exchange occur.
Endobronchial valves are inserted using a bronchoscope into sections of the lungs damaged by emphysema. Endobronchial valves are medical devices that allow air to exit these sections but not to re-enter. The valves, in effect, cause damaged lung tissue to deflate, thereby reducing the excessive lung volume (hyperinflation) caused by emphysema.
Endobronchial valve. An endobronchial valve (EBV) is a small, one-way valve, which may be implanted in an airway feeding the lung or part of lung. The valve allows air to be breathed out of the section of lung supplied, and prevents air from being breathed in. This leaves the rest of the lung to expand more normally and avoid air-trapping.
In the iron lung by means of a pump, the air is withdrawn mechanically to produce a vacuum inside the tank, thus creating negative pressure. [41] This negative pressure leads to expansion of the chest, which causes a decrease in intrapulmonary pressure, and increases flow of ambient air into the lungs.
Volume controlled ventilation is ventilation where both volume and flow are controlled by the ventilator. Normally, flow is set to a fixed amount, meaning volume increases linearly over time. Any mode that relies on flow to control inspiration falls under the VC- category.
Ventilators may also be equipped with monitoring and alarm systems for patient-related parameters (e.g., pressure, volume, and flow) and ventilator function (e.g., air leakage, power failure, mechanical failure), backup batteries, oxygen tanks, and remote control. The pneumatic system is nowadays often replaced by a computer-controlled turbopump.
Pressure control is used to regulate pressures applied during mechanical ventilation. Air delivered into the patients lungs (breaths) are currently regulated by Volume Control or Pressure Control. In pressure controlled breaths a tidal volume achieved is based on how much volume can be delivered before the pressure control limit is reached. [1]