The lung is moderately congested with blood and collapsed, due to absorption of air trapped by obstruction of airways (bronchi and bronchioles). The large and medium-sized bronchioles are thick-walled and they are filled with greyish-white, jelly-like mucus plugs. It is these plugs, rather than spasm of airway muscle, that have caused the partial collapse of the lung, unconsciousness, low arterial oxygen and high carbon dioxide. The blood vessels in the vicinity of the bronchi contain blood clot.