Background: Thoracic epidural analgesia (TEA) combined with general anesthesia decreases anesthetic requirements by half when hemodynamic criteria are used for the titration of analgesia. We therefore determined the impact of TEA on anesthetic requirements, when a closed-loop controller was used allowing the automated coadministration of propofol-remifentanil guided solely by the Bispectral index.
Methods: This single-center double-blind study enrolled patients scheduled for elective posterolateral thoracotomy using TEA. Patients were randomly assigned to receive a bolus followed by a continuous infusion of levobupivacaine 0.5% (levo group) or saline 0.9% solution (saline group). General anesthesia was performed by the same automated controller. Stroke volume optimization guided by an esophageal Doppler probe was performed before randomization. The primary outcome variable was the amount of remifentanil delivered by the automated controller between skin incision and closure. Major arterial hypotension was recorded. Data are presented as medians [interquartile range] or number (%) RESULTS:: Nineteen adult patients per group completed the study. At similar depth of anesthesia evaluated by the percentage of time with the Bispectral index in the range 40-60 (85 [77-88] vs 83 [72-87]; P = .39), patients with neuraxial block required less remifentanil (0.15 [0.10-0.20] vs 0.23 [0.14-0.25], µg·kg·min; P = .03) and propofol (4.3 [3.7-4.9] vs 5.7 [4.6-7.3] mg·kg·h; P = .005). Major arterial hypotension was similar in both groups (6 [32%] vs 5 [25%]; P = .46; levo versus saline group, respectively).
Conclusions: Epidurally administered levobupivacaine allowed a decrease by one-third of remifentanil requirement. After stroke volume optimization, major arterial hypotension was similar between groups.