Morphine Postoperative Analgesia and Pharmacokinetic/Pharmacodynamic Modeling

Pharmacokinetic/Pharmacodynamic Modeling of Morphine for Postoperative Analgesia Through a Patient Controlled Device After Coronary Artery Bypass Grafting. Intrathecal Morphine Significantly Reduces Drug Consumption

The currently available data are insufficient to develop a model that achieves optimum morphine dose individualization at the postoperative period of coronary artery bypass grafting (CABG). Therefore, the objective of the study was to apply a PK/PD model that could justify morphine consumption, drug plasma concentration and pain intensity during the postoperative period after CABG and evaluate the post operative pain.

The protocol was a prospective, open-label study, approved by the institutional ethical committee of the hospital where the study was performed. Patients were randomly assigned to receive general anesthesia plus intrathecal morphine at a dosage of 400 mcg (morphine group) or general anesthesia alone (control group) according to a simple computer-generated list.

Inclusion Criteria:

• eligible to cardiopulmonary artery bypass grafting surgery

Exclusion Criteria:

• fraction of ejection below 40%
• contraindications to neuraxial blockage
• coagulopathy
• use of low-weight heparin
• warfarin or a platelet aggregation inhibitor other than aspirin,
• systemic or local infection
• and patients with a specific contraindication on the medication employed in the study