Influence of Obesity on Propofol Pharmacokinetics During Cardiac Surgeries Using Cardiopulmonary Bypass: Derivation of a Pharmacokinetic Model

Anaesthesia maintenance upon initiation of CPB will be achieved by propofol (1%) bolus (1 mg/kg TBW) immediately followed by 2 mg/kg TBW/hr infusion that will be continued till weaning from CPB. During CPB an additional propofol bolus doses can be administered to prevent awareness according to the clinical judgment of the responsible anaesthesiologist. Any additional doses given and their timings will be recorded.

Blood samples of 2 ml each will be collected from the arterial line of CPB machine until the end of CPB then from sub-clavin arterial catheter routinely inserted in such surgeries. Sampling process will follow the following schedule; at baseline prior to dosing, followed by samples at 1, 3, 5,7 min after the propofol bolus dose, then every 20 minutes during propofol infusion, just before discontinuation of the propofol infusion and at 1, 3, 5, 7, 10, 20, 30, 60 minutes after the end of infusion. In addition, just before any rescue propofol dose administration, an unscheduled sample will be withdrawn