Islamic Interpretation of Dreams (Ibn-i Sirin):

(Hanging) If one strangles himself with his own hands, or if he hangs himself with a rope which he attaches to the ceiling in a dream, it means that he is sufferings from depression, distress, or sorrow.

It also could mean that he will not reside in his present house, or in the place where he saw himself strangled.

The same interpretation goes for seeing oneself suffering from asphyxia.

(Also see Suffocation)