• Carlos R Silva-Filho, Barbosa Ricardo Antonio G RAG Servico de Anestesiologia e Terapia Intensiva Cirurgica Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP Faculdade de Medicina, U, Carlindo V Silva, Malbouisson Luiz M S LMS Servico de Anestesiologia e Terapia Intensiva Cirurgica Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP Faculdade de Medicina, Univer, Carmona Maria José C MJC Servico de Anestesiologia e Terapia Intensiva Cirurgica Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP Faculdade de Medicina, Univer, and Silvia Regina C Jorge-Santos.
• Faculdade de Ciencias Farmaceuticas, Universidade de São Paulo, Sao Paulo, SP, BR.
• Clinics (Sao Paulo). 2018 Jan 1; 73: e178.

ObjectivesThe objective of this study was to apply a pharmacokinetics-pharmacodynamics approach to investigate the free propofol plasma levels in patients undergoing coronary artery bypass grafting under hypothermic conditions compared with the off-pump procedure.MethodsNineteen patients scheduled for on-pump coronary artery bypass grafting under hypothermic conditions (n=10) or the equivalent off-pump surgery (n=9) were anesthetized with sufentanil and propofol target-controlled infusion (2 μg/mL) during surgery. The propofol concentration was then reduced to 1 μg/mL, and a pharmacokinetics-pharmacodynamics analysis using the maximum-effect-sigmoid model obtained by plotting the bispectral index values against the free propofol plasma levels was performed.ResultsSignificant increases (two- to five-fold) in the free propofol plasma levels were observed in the patients subjected to coronary artery bypass grafting under hypothermic conditions. The pharmacokinetics of propofol varied according to the free drug levels in the hypothermic on-pump group versus the off-pump group. After hypothermic coronary artery bypass was initiated, the distribution volume increased, and the distribution half-life was prolonged. Propofol target-controlled infusion was discontinued when orotracheal extubation was indicated, and the time to patient extubation was significantly higher in the hypothermic on-pump group than in the off-pump group (459 versus 273 min, p=0.0048).ConclusionsThe orotracheal intubation time was significantly longer in the hypothermic on-pump group than in the off-pump group. Additionally, residual hypnosis was identified through the pharmacokinetics-pharmacodynamics approach based on decreases in drug plasma protein binding in the hypothermic on-pump group, which could explain the increased hypnosis observed with this drug in this group of patients.

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