Closed-loop assisted versus manual goal-directed fluid therapy during high-risk abdominal surgery: a case–control study with propensity matching

Abstract

IntroductionGoal-directed fluid therapy strategies have been shown to benefit moderate- to high-risk surgery patients. Despite this, these strategies are often not implemented. The aim of this study was to assess a closed-loop fluid administration system in a surgical cohort and compare the results with those for matched patients who received manual management. Our hypothesis was that the patients receiving closed-loop assistance would spend more time in a preload-independent state, defined as percentage of case time with stroke volume variation less than or equal to 12%.MethodsPatients eligible for the study were all those over 18 years of age scheduled for hepatobiliary, pancreatic or splenic surgery and expected to receive intravascular arterial blood pressure monitoring as part of their anesthetic care. The closed-loop resuscitation target was selected by the primary anesthesia team, and the system was responsible for implementation of goal-directed fluid therapy during surgery. Following completion of enrollment, each study patient was matched to a non–closed-loop assisted case performed during the same time period using a propensity match to reduce bias.ResultsA total of 40 patients were enrolled, 5 were ultimately excluded and 25 matched pairs were selected from among the remaining 35 patients within the predefined caliper distance. There was no significant difference in fluid administration between groups. The closed-loop group spent a significantly higher portion of case time in a preload-independent state (95 ± 6% of case time versus 87 ± 14%, P =0.008). There was no difference in case mean or final stroke volume index (45 ± 10 versus 43 ± 9 and 45 ± 11 versus 42 ± 11, respectively) or mean arterial pressure (79 ± 8 versus 83 ± 9). Case end heart rate was significantly lower in the closed-loop assisted group (77 ± 10 versus 88 ± 13, P =0.003).ConclusionIn this case–control study with propensity matching, clinician use of closed-loop assistance resulted in a greater portion of case time spent in a preload-independent state throughout surgery compared with manual delivery of goal-directed fluid therapy.Trial registrationClinicalTrials.gov Identifier: NCT02020863. Registered 19 December 2013Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-015-0827-7) contains supplementary material, which is available to authorized users.

Model-based drug administration

“…The same group extended their system with a minimal invasive cardiac output system measuring stroke volume variation (EV1000, Edwards Lifescience, Irvine, California, USA) and compared its performance to maintain a preload independent state with a manual goal-directed fluid therapy. Also in this case-control study, the closedloop treated group showed a significantly greater portion of case time in a preload independent state compared with the manually treated group [62].…”

Lack of Impact of NPO Time on Goal-Directed Fluid Therapy Resuscitation in AM versus PM Case Starts: A Retrospective Cohort Study

“…We assumed group size imbalance may exist between AM and PM case starts due to the consistent morning starts in all ORs. We knew if we could pull at least 300 patients into the former and 100 patients into the latter, assuming the typical patient received 2100 ± 450 ml of fluid based on previous work 12 , with a power of 0.8 and alpha of 0.05, we would sufficiently power our analysis to detect a difference of approximately 300ml of fluid between the groups. With a minimum NPO time difference of 2.5 hours between groups, this represented the ability to detect a need of as little as 120 ml of 'deficit' fluids between groups per hour of NPO time.…”

The Feasibility of a Completely Automated Total IV Anesthesia Drug Delivery System for Cardiac Surgery

“…An ultimate system such as this should not only automatically administer fluid therapy, because it has already been successful for major noncardiac surgery, 28 but should also automatically deliver vasoconstrictors and inotropic agents when low systemic vascular resistance and low cardiac output syndrome are present. A combined optimal robotic anesthesia and perfusion system for cardiac anesthesia that would reduce attending anesthesiologists' workload, allowing them to concentrate on a higher level of care requiring human intelligence, will make a difference in cardiac patients' outcomes.…”