While ventilating an unresponsive man with a bag-mask device, you hear gurgling in his upper airway. You should

First, you should immediately stop the ventilation. The gurgling sound indicates that there is a blockage in the airway, likely due to fluid such as vomit or blood.

Next, you should perform a head-tilt chin-lift maneuver to open the airway. This involves placing one hand on the patient's forehead and the other on the chin, then tilting the head back and lifting the chin up.

If the gurgling continues, you should use a suction device to remove the fluid. This involves inserting a suction catheter into the mouth and down the throat, then turning on the suction to remove the fluid.

Once the airway is clear, you can resume ventilation. However, you should continue to monitor the patient closely for any further signs of airway obstruction.

Remember, always follow your local protocols and guidelines when providing medical care.