I think that refers to any way you cut off oxygen to the brain? *looks it up*
"Condition caused by insufficient intake of oxygen. Extrinsic causes include choking, toxic gases, exhaust gas (principally carbon monoxide), electric shock, drugs, anesthesia, trauma, crushing injuries of the chest, Compression of the chest, injury of the respiratory nerves or center, diminished environmental oxygenation, and drowning."
Yea I was right. Maybe a bag on his head?