Background: Automated titration of intravenous anesthesia or analgesia guided by processed EEG monitoring is no longer a novel concept, and closed-loop fluid administration to provide goal-directed fluid therapy has also been described. However, combining multiple independent physiologic closed-loop systems together simultaneously has not been previously described. The goal of this study was to evaluate the clinical performance of fully automated hypnosis, analgesia and fluid management using two independent closed loop controllers in patients undergoing high risk vascular surgery.
Methods: Thirteen patients were enrolled in this single-center prospective pilot study. Automated fluid administration was based on stroke volume (SV), cardiac output (CO) and stroke volume variation (SVV) obtained by invasive blood-pressure monitoring using the EV-1000 monitor. Patients received a maintenance infusion of 3 ml.kg-1.h-1 of crystalloid and additional fluid administration consisted of 100 ml boluses of colloid delivered via a closed-loop fluid management system. Automated propofol and remifentanil coadministration was based on the bispectral index (BIS) during induction and maintenance of general anaesthesia. The primary objective was to assess the clinical performance of both closed loop systems to provide an adequate hemodynamic profile (defined as a SVV < 13% and/or a cardiac index (CI) ≥ 2.5 l .min-1.m-2) and an adequate depth of anesthesia (defined as a percentage of BIS value between 40-60) for at least 85% of the total operative time.
Results: Patients spent a median [IQR] of 84% [76-89] of their case time in the BIS target range of [40-60] and 99% [97-100] of case time within the predefined target hemodynamic ranges. 
Conclusions: This study demonstrates the clinical ability of dual closed loop systems to maintain their anaesthetic and hemodynamic targets for the majority of the surgical case time in patients undergoing high risk vascular surgery.

Fully automated anesthesia, analgesia and fluid management using physiologic closed-loop systems in high risk patients: a pilot study