Ventilators

Ventilators are medical devices that assist or replace spontaneous breathing by delivering a controlled airway pressure and volume of gas to the patient’s lungs. They are used when patients cannot breathe adequately on their own due to illness, injury, anesthesia, or critical illness. In modern medicine, most ventilators provide positive-pressure breaths through an airway device such as an endotracheal tube or tracheostomy, or via a noninvasive interface such as a face mask or helmet.

A ventilator typically mixes air with oxygen, and can be set to different modes and parameters. It may deliver breaths at a set tidal volume and respiratory rate (volume-controlled modes) or at a preset inspiratory pressure (pressure-controlled modes). Some modes provide full control of every breath, while others synchronize with the patient’s own efforts. Common features include PEEP (positive end-expiratory pressure) to keep airways open and adjustable FiO2 to meet oxygen needs. Many ventilators also provide noninvasive ventilation (NIV) with interfaces like masks or helmets, including CPAP and BiPAP modes.

Invasive ventilation requires an endotracheal tube or tracheostomy; noninvasive ventilation uses masks or helmets. The devices are used in intensive care units, operating rooms, emergency departments, and during patient transport. Indications include acute respiratory failure, post-operative respiratory support, coma, neuromuscular disorders, and severe pneumonia or trauma.

Risks include ventilator-associated pneumonia, barotrauma, volutrauma, lung injury from overdistension, mucosal injury, delirium, and hemodynamic effects. Weaning from ventilation involves assessing readiness for spontaneous breathing through spontaneous breathing trials. Historically, ventilation evolved from negative-pressure "iron lungs" to modern positive-pressure systems.