BACKGROUND: Multiple electrode aggregometry (MEA) is a point-of-care test evaluating platelet function and the efficacy of platelet inhibitors. In MEA, electrical impedance of whole blood is measured after addition of a platelet activator. Reduced impedance implies platelet dysfunction or the presence of platelet inhibitors. MEA plays an increasingly important role in the management of perioperative platelet dysfunction. In vitro, midazolam, propofol, lidocaine and magnesium have known antiplatelet effects and these may interfere with MEA interpretation.
OBJECTIVE: To evaluate the extent to which MEA is modified in the presence of these drugs.
DESIGN: An in-vitro study using blood collected from healthy volunteers.
SETTING: Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland, 2010 to 2011.
PATIENTS: Twenty healthy volunteers.
INTERVENTION: Measurement of baseline MEA was using four activators: arachidonic acid, ADP, TRAP-6 and collagen. The study drugs were then added in three increasing, clinically relevant concentrations.
MAIN OUTCOME MEASURE: MEA was compared with baseline for each study drug.
RESULTS: Midazolam, propofol and lidocaine showed no effect on MEA at any concentration. Magnesium at 2.5 mmol l had a significant effect on the ADP and TRAP tests (31 ± 13 and 96 ± 39 AU, versus 73 ± 21 and 133 ± 28 AU at baseline, respectively), and a less pronounced effect at 1 mmol l on the ADP test (39 ± 0 AU).
CONCLUSION: Midazolam, propofol and lidocaine do not interfere with MEA measurement. In patients treated with high to normal doses of magnesium, MEA results for ADP and TRAP-tests should be interpreted with caution.
TRIAL REGISTRATION: Clinicaltrials.gov (no. NCT01454427).