Encourage the casualty to cough. The person with an effective cough should be given reassurance and encouragement to keep coughing to expel the foreign material
Keep the casualty calm
If the obstruction is not relieved the rescuer should call an ambulance
DO NOT attempt to dislodge the partial blockage by using back slaps or placing fingers in the casualty’s mouth, this can cause a complete blockage.
It is better to be getting SOME air, than NO air at all.