Local anæsthesia / by Arthur Schlesinger ; translated by F.S. Arnold.

  • Schlesinger, Arthur.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Local anæsthesia / by Arthur Schlesinger ; translated by F.S. Arnold. Source: Wellcome Collection.

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    affinity between the drug and the protoplasm of the tissues, which gives rise to a chemical combina- tion, of whose exact composition we are at present ignorant. That the anaemia is not the efficient cause of the anaesthesia is proved by the following facts : 1. Cocain has been found to produce its anaes- thetic effect even when the blood in the vessels has been replaced by salt solution. 2. There is a whole series of preparations which are efficient producers of local anaesthesia, but do not cause simultaneous anaemia—e.g., eucain. The aqueous solutions of cocain which were in general use until the introduction of the modern substitutes are all strongly hyposmotic or hypo- tonic. Their freezing-point varies, according to Braun, from 0'02°(0'1 per cent, solution) toOT15°C. ( l per cent, solution), the freezing-point of human blood being about 0'55° C. Their injection, never- theless, causes no “ infiltration pain ” (Quellungs- schmerz), as this is overborne by the essential anaesthetic effect of the drug. Different kinds of protoplasm have different degrees of chemical affinity for cocain ; what chief! y concerns us is the high degree of affinity in the case of the sensory nerves. Thus, according to Braun, a 0*005 per cent, solution of cocain injected so as to produce a weal is sufficient to deaden for a short time the sensory nerve-endings within the
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