In vitro effect of clinical propofol concentrations on platelet aggregation.

The inhibitory effect of propofol on platelet aggregation remains unclear, and studies on the subject disagree. Furthermore, although propofol infusions are widely used for general anesthesia and as sedatives for patients in intensive care units, little information is available on its concentration- and time-related effects on platelet aggregation. Here, the authors investigated the in vitro effect of propofol, at concentrations required for sedation and general anesthesia, on platelet aggregation after 1, 2, or 3 h. Blood from healthy volunteers (n = 9) was incubated at propofol plasma concentrations of 0, 2, 4, and 10 µg/mL in a water bath at 37°C. Platelet aggregation was measured using a platelet function analyzer (PFA-100) after 1, 2, or 3 h of incubation. Times to occlude collagen/epinephrine (CEPI) or collagen/adenosine 5'-diphosphate (CADP)-coated membranes (closure times, CTs) were measured. The CEPI and CADP CTs of non-incubated blood were 125.6 ± 19.5 s and 93.0 ± 12.2 s, respectively, and no significant difference in CEPI CTs was observed at propofol plasma concentrations of 0, 2, 4, and 10 µg/mL after incubation for 1, 2, or 3 h. CADP CTs were comparable at propofol concentrations of 0, 2, 4, and 10 µg/mL at each incubation time. These findings suggest that propofol at concentrations required for sedation and general anesthesia has no inhibitory effect on platelet aggregation after 3 h of incubation.

In vitro effect of clinical propofol concentrations on red blood cell aggregation and deformability.

This in vitro study investigated time-related effects of propofol at the plasma concentrations required for sedation and general anaesthesia, on RBC aggregation, deformability, and morphology. Blood containing propofol at plasma concentrations of 0, 2 and 4 µg ml-1 was incubated in a water bath at 37°C for 1, 2, or 4 hours. RBC elongation indices (EIs) and aggregation indices (AIs), which represent RBC deformability and aggregation, respectively, were measured. Also, RBC morphological indices (MIs), which represent RBC morphology, were calculated. EIs and AIs were similar at propofol concentrations of 0, 2, or 4 µg ml-1 after 1, 2, or 4 hours of incubation. MIs at propofol plasma concentrations 0 or 2 µg ml-1 were similar after 1, 2, and 4 hours of incubation, however, MI at a propofol concentration of 4 µg ml-1 after 4 hours of incubation was higher than its value after 1 or 2 hours of incubation. No significant difference was observed between MIs at propofol plasma concentrations 0, 2, or 4 µg ml-1 after 1, 2, and 4 hours of incubation. At clinical doses, propofol has no direct effects on RBC deformability, aggregation, or morphology over a 4 hours incubation period.