Final answer:
The bag-valve mask is operated by one person, typically a trained medical professional. It is a device used to provide positive pressure ventilation to a patient who is not breathing adequately.
Step-by-step explanation:
The bag-valve mask is operated by one person, typically a trained medical professional. It is a device used to provide positive pressure ventilation to a patient who is not breathing adequately. The person operating the bag-valve mask squeezes the bag to deliver air into the patient's lungs. The mask is often used in emergency situations or during anesthesia.