10 Pharmacology of the Interaction between Platelets and Vessel Wall

Use of desmopressin to prevent bleeding complications in patients treated with aspirin

Aspirin induces a haemorrhagic diathesis that persists for at least 1 week after discontinuation of the drug. The effect of the vasopressin analogue desmopressin was studied in 12 patients treated with aspirin who were undergoing cholecystectomy. Desmopressin was given to six of these patients. There were five postoperative bleeding complications; all occurred in patients who had not received desmopressin (P < 0.05). The bleeding time was prolonged in aspirin-treated patients and normalized by desmopressin (P < 0.05). Desmopressin can be used safely to prevent bleeding induced by aspirin.

The effect of anaesthetic agents on platelet function

This paper reviews studies which have investigated the effect of anaesthetic agents on platelet function. The results of these studies suggest that halothane is the only agent in current use which inhibits platelet function in concentrations used clinically. Nitrous oxide appears to cause only a modest inhibition, while enflurane and isoflurane appear to have minimal or negligible effects. There is no current evidence that intravenous induction agents, opiates, or muscle relaxants affect platelet function. Reports indicate that local anaesthetic agents inhibit platelet aggregation, but only at concentrations far greater than peak plasma concentrations found during clinical use. Epidural anaesthesia may be associated with a reduction in platelet aggregation through a mechanism unrelated to direct local anaesthetic inhibition. The clinical significance of the effect of halothane on platelet function is not known. However, it is possible that halothane may affect bleeding or thrombotic complications in a similar manner to other 'anti-platelet' drugs.