Quantification of blood from skin bleeding time determinations: effects of fish diet or acetylsalicylic acid.

The Simplate II technique for measuring bleeding time was adapted to quantify the volume of blood as a function of time and for determining how this parameter was affected by either acetylsalicylic acid (ASA) or a dietary supplement of fish. Both increased the bleeding time significantly. Irrespective of the final bleeding time, the rate of blood loss increased for about the first 2 min and then decreased almost linearly until bleeding stopped. This time course was not affected by either ASA or the fish diet. The lack of effect by ASA suggests that the initial increase in bleeding time, presumably due to reversal of vasoconstriction, does not involve prostaglandin derivatives. After ASA the rate of blood loss was significantly greater throughout, probably caused by deceleration of platelet aggregation. During the fish diet, when bleeding time was increased, there was no change in the rate of blood loss until the last 2-3 min during which bleeding continued at a very low rate. The results support the conclusion that the delay in primary haemostasis produced by a fish diet is due to a different mechanism than that produced by ASA.