What Causes Foam Like Vomiting Despite Being Diagnosed With COPD?

Hi,I have a friend who is 72 yrs old and is vomiting foam. she has been tested and gone to the hospital for her heart condition and COPD and they say all is well. She has a pace maker and has had open heart surgery with in the last 5 years. she is suffering from dizziness and the only way she feels comfortable is laying down with her eyes closed...but the foam is what is alarming to her. could you please lend a suggestion...