  This paper presents a delay-dependent parameter-varying control design
approach to address the automated blood pressure regulation problem in the
critical patient resuscitation using closed-loop administration of
vasopressors. The mean arterial pressure (MAP) response of a patient subject to
the intravenous vasoactive drug treatment is modeled as a linear
parameter-varying (LPV) model, where varying model parameters and varying
time-delay are considered as scheduling parameters of the system.
Parameter-dependent Lyapunov-Krasovskii functionals are used to design an
output-feedback dynamic controller to satisfy the closed-loop stability and
reference MAP tracking requirements. The synthesis conditions are formulated in
terms of Linear Matrix Inequalities (LMIs) that characterize the induced
$\mathcal{L}_2$-norm performance specification of the closed-loop system. The
main objectives of the proposed control method in the presence of limitations
posed by the time-varying model parameters and the large time-varying delay are
to track the MAP reference command and maintain the blood pressure within the
permissible range of commanded set-point, avoid undesirable overshoot and slow
response, and to provide a smooth drug injection. Finally, to evaluate the
performance of the proposed LPV blood pressure regulation approach, closed-loop
simulations are conducted and the results confirm the effectiveness of the
proposed control method against various simulated scenarios.
