A 50-year-old patient is not breathing and has a faint pulse. What should you do?

In a scenario where a patient is not breathing but has a faint pulse, the immediate priority is to ensure that the patient is receiving adequate oxygenation and ventilation. Administering bag-valve mask (BVM) ventilation is crucial because it provides positive pressure ventilation, which helps to deliver oxygen directly to the patient's lungs.

When a patient is not breathing, various respiratory issues could prevent them from taking in oxygen effectively. It's important to take action to support their respiratory function, particularly since the patient still has a faint pulse, which indicates that some circulation is present. By using a bag-valve mask, you can help to maintain oxygen levels and support respiratory function until more advanced care can be administered.

While other options may seem relevant in different contexts—such as using a defibrillator for a patient who has gone into cardiac arrest—those would not be appropriate if the patient retains a pulse, even if faint. Administering supplemental oxygen via a nasal cannula wouldn't adequately address the immediate need for ventilation in a patient who is not breathing. Therefore, starting with bag-valve mask ventilation is the best course of action in this situation to ensure the patient receives the necessary oxygenation.