Virchow on Oxygen and Thromboembolism

Virchow (1856) recognised that thrombosis (and thromboembolism) is oxygen-dependent. He inquired whether the oxygen is already present in the circulating blood or must be supplied from outside the body. If it is introduced from outside the body there must be either (1) a breach in the vessel wall, or (2) absorption through exposed wounds, ulcers or various orifices. He reasoned against these possibilities. But if oxygen is already present in the circulating blood, carried by the 'red corpuscles', how is it liberated so as to cause coagulation? Of course, this work was conducted long before the structure and function of haemoglobin were understood; but it is interesting to see how Virchow wrestled with the problem. He rejected the hypothesis that there is a 'spontaneous change in the interior constitution of the blood particles' because this 'could only be conceded if found still present in blood long stagnant'. He went on to suggest that 'A more considerable change in the blood-vessels might be postulated, where molecular attraction between the blood and the vessel wall is seen to increase, especially when the blood comes into contact with porous foreign bodies. ... A fibrolami-nar clot ... in a retarded blood-flow can initiate that linking of the fibrogenous substance with oxygen liberated from the blood corpuscles, and can organise about itself by attraction new fibrous material, which then takes effect as a new aggregation of contact bodies.' He then proposed, once again echoing his predecessors, that 'thickening and irregularity of the vessel lining may predispose to thrombus formation'.

It is striking that Virchow recognised that the coagulation of blood, and the formation of thrombi and emboli, is oxygen-dependent. But he also knew that altered blood movement - and therefore, by implication, local hypoxaemia - is a causal factor in thromboembolism. (Incidentally, the word ischaemia is another of his additions to the medical vocabulary.) In this respect as in others, his contribution to the field was a milestone.

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