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TRANSLATIONAL PHYSIOLOGY

Automated drug delivery system to control systemic arterial pressure, cardiac output, and left heart filling pressure in acute decompensated heart failure

¹Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Suita; ²Research Division on Advanced Information Technology, Information Synergy Center, Tohoku University, Sendai; ³Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Science, Fukuoka, Japan

Submitted 22 September 2005 ; accepted in final form 17 December 2005

ABSTRACT

Pharmacological support with inotropes and vasodilators to control decompensated hemodynamics requires strict monitoring of patient condition and frequent adjustments of drug infusion rates, which is difficult and time-consuming, especially in hemodynamically unstable patients. To overcome this difficulty, we have developed a novel automated drug delivery system for simultaneous control of systemic arterial pressure (AP), cardiac output (CO), and left atrial pressure (Pla). Previous systems attempted to directly control AP and CO by estimating their responses to drug infusions. This approach is inapplicable because of the difficulties to estimate simultaneous AP, CO, and Pla responses to the infusion of multiple drugs. The circulatory equilibrium framework developed previously (Uemura K, Sugimachi M, Kawada T, Kamiya A, Jin Y, Kashihara K, and Sunagawa K. Am J Physiol Heart Circ Physiol 286: H2376–H2385, 2004) indicates that AP, CO, and Pla are determined by an equilibrium of the pumping ability of the left heart (S_L), stressed blood volume (V), and systemic arterial resistance (R). Our system directly controls S_L with dobutamine, V with dextran/furosemide, and R with nitroprusside, thereby controlling the three variables. We evaluated the efficacy of our system in 12 anesthetized dogs with acute decompensated heart failure. Once activated, the system restored S_L, V, and R within 30 min, resulting in the restoration of normal AP, CO, and Pla. Steady-state deviations from target values were small for AP [4.4 mmHg (SD 2.6)], CO [5.4 ml·min^–1·kg^–1 (SD 2.4)] and Pla [0.8 mmHg (SD 0.6)]. In conclusion, by directly controlling the mechanical determinants of circulation, our system has enabled simultaneous control of AP, CO, and Pla with good accuracy and stability.

computers; negative feedback; circulatory equilibrium