[Prolongation and normalization of bleeding time during therapy with different doses of acetylsalicylic acid].

The present study investigated whether there is a statistically significant correlation between platelet aggregation inhibition (TAI) and prolongation of subaqueous bleeding time (SBT) under therapy with 40 mg (n = 20) and 500 mg (n = 20) acetylsalicylic acid (ASA) daily and when parameters return to normal after discontinuation of long-term (4 weeks) and short-term (1 week) treatment. The results of this study may be helpful in clinical practice when deciding upon indications for certain operative or anaesthetic procedures. RESULTS. Under ASA treatment, neither TAI nor prolongation of SBT was dependent on dosage or time (Figs. 1-4). After discontinuation of ASA, platelet aggregation returned to normal 1-4 days later than SBT, depending on the dosage and duration of medication. SBT declined to its initial value on the 3rd day following discontinuation of ASA in both dosage groups (Figs. 2 and 4). Normalisation of platelet aggregation depended on dosage: in those groups with 40 mg ASA, thrombocyte aggregation had normalised on the 4th day irrespective of duration of medication; in groups with 500 mg aggregation capacity was completely restored on the 5th day after 1-week therapy and on the 7th day after 4-week therapy (Figs. 1 and 3). Considering these results, an important factor is the time of discontinuation of ASA intake. Prior to scheduled operative procedures or regional anaesthetics near the spinal cord, ASA should be discontinued, depending on the dosage, 2-3 days ahead. At this time SBT has reached the initial value, however, the aggregation capacity of thrombocytes is still reduced for a few days.(ABSTRACT TRUNCATED AT 250 WORDS)