Blood loss and blood transfusion.

The assessment of blood loss following injury may be of considerable value when considering the question of replacement of such loss. The clinical picture of "traumatic shock"—hypotension, pallor, coldness of the extremities and cyanosis, suggests that urgent treatment is necessary. However, this picture may not be evident immediately after injury, despite its severity, particularly in young healthy individuals, and its development may be delayed for some hours until the compensatory mechanism begins to faiL It is therefore of the utmost importance to have a means of assessing the probable blood loss so that treatment may be initiated before the clinical picture of "shock" has become obvious. The aim should be to obtain an estimate of the probable loss which, while it will not be exact, will nevertheless provide a reasonable basis for resuscitation.