Otimização da administração do propofol para indução anestésica em cães

Abstract

Propofol is the most commonly used intravenous general anesthetic for anesthetic induction in dogs. It presents favorable pharmacokinetic and pharmacodynamic characteristics, enabling rapid, smooth induction with good quality recovery. Despite this, some important adverse effects are frequently reported, such as cardiovascular and respiratory depression, which are dose-dependent. Its administration is intravenous and can be performed manually or via continuous infusion, with the dose being titrated to effect. Given the relevance of the potential adverse effects, many authors seek alternatives to reduce the dose of propofol required for anesthetic induction. More recent studies have shown that the rate of drug administration is directly related to the required dose; therefore, it is recommended that its infusion be carried out more slowly. However, there are still few practical guidelines regarding the ideal relationship between dose and administration time. In addition to the infusion rate, the type of premedication used can influence the adverse effects observed after anesthetic induction with propofol. The main sedative drugs used for this purpose are acepromazine and dexmedetomidine, often combined with an opioid. Among opioids, methadone has gained popularity for providing a superior sedative effect compared to other drugs in the same class, along with a low probability of emesis and histamine release, in addition to its well-known analgesic effect. Since propofol is frequently administered for anesthetic induction in dogs premedicated with a combination of acepromazine and methadone or dexmedetomidine and methadone, the present thesis aims to provide a theoretical framework describing the pharmacokinetic and pharmacodynamic characteristics of these drugs and, subsequently, to present two scientific articles addressing research on the administration technique and the influence of premedication using a fixed rate of propofol administration in dogs.