Submitted on September 21, 2005
Accepted on December 17, 2005
Automated drug delivery system to control systemic arterial pressure, cardiac output, and left heart filling pressure in acute decompensated heart failure
Kazunori Uemura1*, Atsunori Kamiya1, Ichiro Hidaka1, Toru Kawada1, Shuji Shimizu1, Toshiaki Shishido1, Makoto Yoshizawa2, Masaru Sugimachi1, and Kenji Sunagawa3
1 Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Suita, Osaka, Japan
2 Research Division on Advanced Information Technology, Tohoku University, Information Synergy Center, Sendai, Miyagi, Japan
3 Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Science, Fukuoka, Fukuoka, Japan
* To whom correspondence should be addressed. E-mail: kuemura{at}ri.ncvc.go.jp.
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 (Am J Physiol 286; H2376, 2004) indicates that AP, CO, and PLA are determined by an equilibrium of the pumping ability of the left heart (SL), stressed blood volume (V) and systemic arterial resistance (R). Our system directly controls SL 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 SL, V and R within 30 minutes, 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.
