Pharmakokinetik Volatiler Anästhetika - Effekte von Herzzeitvolumen und Ventilation auf die Kinetik von Desfluran und Sevofluran

Durch die Variation von Herzzeitvolumen und Ventilation sollen die Kinetiken von Desfluran und Sevofluran detailliert beschrieben werden. Durch Erhöhung des Herzzeitvolumens bei gleichzeitiger Reduktion der Ventilation und umgekehrt soll die Pharmakokinetik der Inhalationsanästhetika im Tiermodell weiter untersucht werden.

The main factors determining alveolar and subsequent blood concentrations of inhaled anesthetics are alveolar ventilation and pulmonary perfusion (VA/Q), the latter essentially equal to cardiac output. The changes of uptake and elimination of a volatile based on uneven distribution of ventilation and/or perfusion have been demonstrated [1]. The solubility of the agent, pressure gradients between alveoli and pulmonary blood, and redistribution of volatiles from peripheral tissues are additional factors that modify the anesthetic blood concentration. The pharmacokinetics of volatiles has been studied in physiologic models such as Eger s 4C model [2]. However, this tends to overestimate initial uptake and VA/Q matching is not considered. It only assumes that uptake of anesthetic gas is perfusion-limited. The objective of the present study is to analyze uptake and elimination of simultaneously administered desflurane (DES) and sevoflurane (SEVO) in healthy piglets and under conditions of high and low cardiac output (CO) and minute ventilation (MV; high CO/low MV vs. low CO/high MV).