Hemodynamic regulation using fuzzy logic

After cardiac surgery patients often show a cardiovascular instability, which has to be managed by infusing different vasoactive drugs. This work proposes a closed-loop system to automatically react upon changes in the patients state and trigger infusion of indicated drugs. As input signals mean arterial pressure, cardiac output, central venous pressure and systemic vascular resistance were chosen. The vasoactive drugs used are isosorbide dinitrate, norepinephrine, dopamine and additionally hydroxyethyl starch. The controller itself is designed as a controller system with four internal fuzzy controllers, one for each medication dosage to be calculated. The proposed controller is tested with a simulation environment. The environment is able to simulate a canine cardiovascular system and reactions to different medications. The controller is evaluated for three different diseases, for congestive heart failure, hypotension and hypertension. The fuzzy controller system is able to react adequately in all these test cases in the simulation and regulates the hemodynamic signals back within a range of the desired target values.