Anesthetic Agents and Platelet Aggregation

In Response: There are obviously controversies about the possible effect of several anesthetics on platelet aggregation, perhaps due to the different technical approaches and interpretations of the results from study to study. Our investigation was in vitro. In no part of our paper do we extrapolate directly to in vivo conditions. Our results only describe a different behavior of propofol in vitro between two types of samples: isolated platelets and whole blood. In whole blood, erythrocytes and/or leukocytes play an important role in platelet function and in its inhibition by drugs. The in vitro effect of propofol is influenced by the nitric oxide-cGMP pathway interaction with platelet-leukocyte [1]. For that reason, we think that whole blood aggregometry could demonstrate better than isolated platelets the inhibitory effect of propofol. Even more, we obtained recent in vivo results in whole blood aggregometry in patients who received a bolus of propofol [1]. In these patients, platelet function in isolated platelets was not modified statistically, but using whole blood aggregometry, we observed an inhibitory effect 5 min after the propofol bolus (50% effective dose for collagen 0.5 micro g/mL before bolus, 1.9 micro g/mL after bolus); moreover, plasma nitrites (as indicators of nitric oxide production) were increased after the propofol bolus. In conclusion, our study is the first step of an investigation that requires other consecutive steps to obtain a definitive conclusion. J.P. De La Cruz J.A. Carmona M.V. Paez E. Blanco F.