Internal Appearances Due to Asphyxia.—The VEINS of the entire body are distended with very dark and very fluid blood, while the arteries, especially in the young, are mostly empty. Experiments on the lower animals have shown that the pulmonary artery and systemic veins to the finest ramifications are distended with dark blood.[777]
The Heart.—The right side, especially the auricle, is usually full of dark fluid blood, due to the mechanical impediment to the passage of blood through the lungs. If the heart continues to beat after the respiration has ceased the right ventricle is commonly well contracted, like the left cavities, and nearly empty, the lungs being much congested. Sometimes the left cavities of the heart contain blood. This would be most likely to occur if the heart should stop in the diastole. Sometimes clots are found in the right ventricle. Maschka[778] found clots in the heart 25 times in 234 cases of asphyxia.
The LUNGS are usually much congested, resembling red hepatization, except that the blood is darker. Hemorrhages (apoplexies) into the substance of the lungs are common. Tardieu found patches of emphysema due to rupture of the surface air-vesicles, giving the surface of the lung the appearance of a layer of white false membrane. Ogston admits this occurrence in pure strangulation but to a less extent in mixed cases. Liman[779] found the lung surface uneven, bosselated, the prominences being of a clearer color and due to emphysema. The lungs were in the same condition of congestion and emphysema in strangulation, suffocation, and hanging. He failed to find the apoplexies described.
The lungs are sometimes anæmic. In healthy young subjects, especially children, the blood-vessels of the lungs often empty themselves after the heart stops. The lungs may, therefore, be bloodless, but emphysematous from the violent efforts to breathe. Page’s experiments on the lower animals showed the lungs of a pale reddish color and not much distended; a few dilated air-cells might be seen toward their anterior borders, and there might be small hemorrhages over the surface. His experiments appear to show that subpleural ecchymoses occur as a result of violent and repeated efforts to breathe. Among other experiments[780] he stopped the mouth and nostrils of a young calf long enough to excite violent efforts at respiration; it was then instantly killed by pithing. The lungs were found pale red, not congested, but showed subpleural ecchymoses. Page believed these were due to the changed relation between the capacity of the thorax and volume of lungs. Liman found these ecchymoses in cases of strangulation, hanging, drowning, poisoning, hemorrhage, and œdema of brain, in the new-born, etc. He failed to find them in some cases of suffocation. He believes them due to blood pressure from stasis in the blood-vessels. Ssabinski[781] made many experiments on dogs and cats to ascertain the presence or absence of subpleural ecchymoses in strangulation, drowning, section of pneumogastrics, opening of pleural sac, compression of chest and abdomen, closure of mouth and nose, burial in pulverulent materials, etc. Similar hemorrhages may appear on the mucous and serous membranes, as the respiratory, digestive, and genito-urinary tracts, and pleuræ, pericardium, peritoneum, membranes of brain, and the ependyma. These are sometimes minute and stellate, at others irregular in shape; many are bright-colored. According to Tardieu the punctiform ecchymoses are rarely present except in suffocation. Maschka,[782] in 234 cases of asphyxia, found the lungs congested 135 times, anæmic 10, and œdematous 42. He thinks the subpleural ecchymoses valuable signs of asphyxia.
The BRONCHIAL TUBES are usually full of frothy, bloody mucus, and the mucous membrane is much congested and shows abundant ecchymoses.
The lining membrane of the LARYNX and TRACHEA is always congested and may be livid; the tube may contain bloody froth or blood alone.
Tidy comparing strangulation and hanging concludes that because strangulation is usually homicidal, and greater violence is used, therefore the external marks are more complete in strangulation and the congestion of the air passages is invariably much greater.
Maschka found the PHARYNX cyanotic in 216 of 234 cases of asphyxia.
The other MUCOUS MEMBRANES are generally much congested. Serum is found in the serous cavities.
Maschka[783] considers the rounded, pin-head ecchymoses of the inner surface of the scalp and pericranium valuable evidence of asphyxia.