Dziekanski - restraint asphyxia?

An article in The Province [LINK] is headlined:

Robert Dziekanski may have died from suffocation while restrained

Although I'm absolutely-positively not an expert on this topic, I understand that such a proposed asphyxia death would normally leave obvious pathological clues.

1. Pulmonary edema, with froth in trachea and bronchi.
2. Bulky, crepitant and over‑distended lungs.
3. Right ventricular dilatation.
...and possibly more...

Ref.: Asphyxia, Dr. J.A.J. Ferris [LINK]

On the other hand, a hypothetical taser-induced death might leave no physical evidence whatsoever (which should be interpreted as very strong evidence in itself).

So, this speculation seems to be perfectly meaningless. If asphyxia is the cause of death, then the autopsy results should indicate asphyxia and provide some details to justify that conclusion. On the other hand, if the autopsy results are inconclusive, then that lack of evidence would point in another direction.