Which device is used to provide positive pressure ventilation to patients?

The bag-valve-mask (BVM) is specifically designed to provide positive pressure ventilation to patients who are unable to breathe adequately on their own. This device consists of a self-expanding bag, a unidirectional valve, and a facial mask. When the bag is squeezed, it forces air into the patient's lungs, effectively assisting or replacing their breathing. BVMs are particularly valuable in emergency situations where patients may be in respiratory distress or are apneic, allowing for immediate intervention to restore adequate ventilation.

In contrast, the non-rebreather mask is primarily used to deliver high concentrations of oxygen, but it does not facilitate positive pressure ventilation. The oxygen concentrator is a device that generates oxygen from ambient air but does not function as a ventilation device. Lastly, the simple face mask can deliver oxygen but does not provide the controlled, positive pressure needed for effective ventilation. Therefore, the BVM stands out as the best choice for providing positive pressure ventilation in emergency situations.