During inspiration, the ventilator raises pressure within the gas pathway above the pressure in the lungs, creating a gradient that drives gas inward. This externally generated pressure expands the lungs and helps deliver air to the alveoli, where ventilation and oxygenation occur. When delivered pressure decreases, elastic recoil generally reverses the airflow for exhalation.
Patient-specific adjustment matters because the same pressure strategy may not suit different mechanical or gas-exchange conditions. Settings are selected in relation to how the lungs respond to pressure and to the need for alveolar ventilation and oxygenation. Appropriate adjustment can support organ oxygen supply while avoiding excessive pressure that could contribute to pressure-related lung injury.
When spontaneous ventilation is inadequate, externally generated pressure supplies part of the effort needed to move gas into the lungs. This assistance can reduce the work required from the patient’s respiratory muscles while maintaining alveolar ventilation. The clinical goal is not simply to move air, but to improve breathing support and preserve oxygen delivery to vital organs.
The gas may be delivered through a mask or an airway tube. These interfaces provide the connection between the ventilator and the patient’s respiratory system, allowing pressurized gas to reach the lungs. The interface is therefore a practical component of support, while the pressure settings still need to reflect the patient’s lung mechanics and gas-exchange requirements.
Positive pressure ventilation is used during anesthesia, acute respiratory failure, and critical care. These settings share a need for respiratory support when spontaneous ventilation cannot adequately meet physiologic demands. Its application can help maintain alveolar ventilation and oxygenation, reduce breathing effort, and sustain oxygen supply to vital organs while clinicians tailor support to the patient’s condition.
Effective application can reduce the work of breathing and maintain vital-organ oxygen supply, but pressure must be limited appropriately because excessive or poorly adjusted pressure can cause pressure-related lung injury. This balance makes ventilator adjustment central to care: support must be sufficient for alveolar ventilation and oxygenation without exposing the lungs to unnecessary pressure.