What is oligaemia characterized by?

Oligaemia is characterized by a decreased circulating blood volume, which can lead to shock. This condition implies that there is insufficient blood flow to the organs and tissues, which can result in inadequate oxygen and nutrient delivery to cells, potentially leading to organ dysfunction. In the context of shock, a significant drop in blood volume can trigger physiological responses aimed at restoring circulation and perfusion, but if left unaddressed, it can lead to severe complications, including organ failure.

The other options do not accurately describe oligaemia. Increased blood circulation pertains to conditions like hypervolemia, where there is excess blood volume. A full blood supply to organs highlights an adequate or increased blood volume scenario rather than a decrease. Excessive blood transfusions would imply an increase in blood volume rather than a decrease, which diverges from the concept of oligaemia. Thus, option B precisely captures the essence of oligaemia and its clinical implications.